HK1147077B - Amine-aldehyde resins and uses thereof in separation processes - Google Patents

Description

Amine-aldehyde resins and their use in separation processes

Cross Reference to Related Applications

This application is a continuation-in-part application of US application serial No. 11/480,561 filed on 5.7.2006, which is a continuation-in-part application of US application serial No. 11/298,936 filed on 12.12.2005, claiming the benefit of priority of US provisional patent application No. 60/638,143 filed on 23.12.2004 and 60/713,340 filed on 2.9.2005, each of which is hereby incorporated by reference in its entirety. This application, which is also a continuation-in-part of US application serial No. 11/298,936 filed on 12/2005, claims the benefit of priority of US provisional patent application No. 60/638,143 filed on 12/23/2004 and 60/713,340 filed on 9/2/2005, each of which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates to resins for use in separation processes, and in particular to the selective separation of solid and/or ionic species (such as metal cations) from aqueous media. Such methods include froth flotation (e.g., as used in the purification of clay-containing ores), separation of drill cuttings from oil drilling fluids, dewatering of clay and coal slurries, sewage treatment, pulp and paper mill effluent treatment, removal of sand from bitumen, and purification of potable water. These resins include the reaction product of a primary and secondary amine with an aldehyde (e.g., a urea-formaldehyde resin).

Background

Froth flotation process

Industrially, processes for purifying liquid suspensions or dispersions (and especially aqueous suspensions or dispersions) to remove suspended solid particles are very common. For example, froth flotation is a separation method based on the difference between the tendency of different materials to combine with rising air bubbles. It is often desirable to incorporate additives into the froth flotation liquid (e.g., aqueous brine) to improve the selectivity of the process. For example, a "collector" may be used to chemically and/or physically adsorb to one or more minerals to be floated, thereby making them more hydrophobic. On the other hand, "depressants" (typically used in conjunction with collectors) make other materials (e.g. gangue minerals) less likely to bind with air bubbles and therefore less likely to be carried into the froth concentrate.

In this way, certain minerals (e.g. valuable minerals) will show a preferential affinity for air bubbles relative to others (e.g. gangue minerals), causing them to rise to the surface of the aqueous slurry where they are collected in the froth concentrate. Thereby achieving the degree of separation. In the less common so-called reverse flotation process, the gangue is preferentially floated and accumulated at the surface, so that the desired material is removed in the bottom product. Gangue materials are typically referred to as quartz, sand, and clay silicates, as well as calcite, although other minerals (e.g., fluorite, barite, etc.) may be included. In some cases, the material to be purified (i.e., the desired material) is actually comprised primarily of these materials, and small amounts of contaminants are preferentially floated. For example, in the enrichment of kaolin, materials with a variety of industrially significant applications, iron, and titanium dioxide can be separated by flotation (into a froth concentrate) from the impurities, clay-containing ores, leaving a purified kaolin bottoms product.

The manner in which known collectors and depressants achieve their effect is not fully understood and several theories have been proposed. Depressants, for example, may prevent gangue minerals from adhering to the valuable material to be separated, or they may even prevent one or more collectors from adsorbing to the gangue minerals. Regardless of the mechanism, the ability of a depressant to improve selectivity in a froth flotation process can very favorably impact its economics.

In general, froth flotation has been practiced in the enrichment of a wide variety of valuable materials (e.g., ores and metal ores and even high molecular weight hydrocarbons such as bitumen) to separate them from unwanted contaminants that are inevitably co-extracted from natural deposits. One particular froth flotation process of commercial interest involves the separation of bitumen from sand and/or clay, which are ubiquitous in oil sand deposits, such as they are found in the vast asabasca region of alberta, canada. Bitumen is a recognized valuable source of "semi-solid" petroleum or heavy hydrocarbon-containing crude oil, which can be upgraded into a variety of valuable end products, including transportation fuels such as gasoline or even petrochemicals. The oil sands deposit of subbenta was evaluated as containing 1.7 trillion barrels of crude oil containing bitumen, exceeding all reserves of saudi arabia. For this reason, much effort has recently been expended to develop economically viable operations for bitumen recovery, primarily froth flotation based on subjecting an aqueous slurry to extraction of petroleum sands. For example, the "Clark process" involves the recovery of bitumen in a froth concentrate while suppressing sand and other solid impurities.

Various gangue depressants for improving froth flotation separation processes are known in the art and include sodium silicate, starch, tannic acid, dextrin, lignosulfonic acid, carboxymethyl cellulose, cyanide salts, and many others. More recently, certain synthetic polymers have been found to be advantageous in particular beneficiation processes using froth flotation. For example, US patent No. re.32,875 describes the separation of gangue from phosphate minerals (e.g., apatite) using a phenolic copolymer (e.g., a resol, a novolac) or a modified phenolic polymer (e.g., a melamine modified novolac) as a depressant.

US patent No. 3,990,965 describes the separation of iron oxide from bauxite using a water-soluble prepolymer with low chain length as depressant, which can selectively adhere to the gangue and can be further polymerized to obtain a crosslinked insoluble resin.

US patent No. 4,078,993 describes the separation of sulphide or oxidised sulphide ores (e.g. pyrite, pyrrhotite or sphalerite) from metal mineral ores (e.g. copper, zinc, lead, nickel) using a solution or dispersion of a low molecular weight condensation product of an aldehyde with a compound containing 2-6 amine or amide groups as a depressant.

US patent nos. 4,128,475 and 4,208,487 describe the separation of gangue materials from mineral ores using a conventional foaming agent (e.g. pine oil) in combination with an amino aldehyde resin (preferably alkylated) which may have free methylol groups.

US patent No. 4,139,455 describes the separation of sulfide or oxidized sulfide ores (e.g., pyrite, pyrrhotite, or sphalerite) from metal mineral ores (e.g., copper, zinc, lead, nickel) using an amine compound (e.g., a polyamine) as a depressant, at least 20% of the total number of amine groups in the amine compound being tertiary amine groups and wherein the number of quaternary amine groups is from 0 to no greater than 1/3 of the number of tertiary amine groups.

US patent No. 5,047,144 describes the separation of siliceous materials (e.g. feldspar) from minerals (e.g. kaolin) using a condensation product of a cationically active aminoplast blowing agent with formaldehyde in combination with a cationically active surfactant (e.g. organic alkyl amines) or an anionically active surfactant (e.g. long chain alkyl sulfonates) as a depressant.

Russian patent nos. 427,737 and 276,845 describe the use of carboxymethyl cellulose and urea-formaldehyde resins, optionally in combination with methacrylic acid-methacrylamide copolymers or starch (' 845 patent), to precipitate clay slimes.

Russian patent nos. 2,169,740, 2,165,798 and 724,203 describe the precipitation of clay carbonate slimes from ores in the potassium industry including sylvinite (KCl-NaCl). The depressant used is a polyethylene polyamine modified urea/formaldehyde condensation product. In addition, guanidine-formaldehyde resins were used (the' 203 patent).

Markin, a.d. et al describe the use of urea-formaldehyde resins as carbonate clay inhibitors in the flotation of potassium ores. Study of the Hydrophilizing Action of Urea-formaldehydes Resins on carbon Clay impritides in Potasum Ores, inst. Obshch. Neorg. Khim, USSR, Vestsi AkademiNavuk BSSR, Serrya Khimichk Navuk (1980); effective of Urea-formaldehyderesins on the circulation of Potasesurus, Khimicheskaya promyslenest, Moscow, Russian Federation (1980); and Adsorption of Urea-formaldehyderesins on Clayminerals of Potassies Ores, Inst.Obshch New.Khim., Minsk, USSR, Dokladdy Akademii Nauk BSSR (1974).

As is recognized in the art, a variety of materials may be enriched/refined by froth flotation. Also, the properties of the desired and undesired components are very different. This is due to the differences in the chemical composition of these materials, as well as the previous chemical treatments and types of treatment steps used. Thus, the number and type of froth flotation depressants is correspondingly wide.

Also, the use of a given depressant in an application (e.g., enrichment of crude potassium ore) does not predict its utility in applications involving a significantly different feedstock (e.g., bituminous oil sands). This also applies to any expectation regarding the use of effective depressants in froth flotation, in any separation of solid contaminants from aqueous liquid suspensions, as described below (and vice versa). The theoretical mechanisms by which froth flotation and aqueous liquid/solid separation occur are significantly different, with the former process relying on differences in hydrophobicity and the latter on several other possibilities (charge instability/neutralization, agglomeration, host-guest theory (including multidentate ligands), soft-hard acid-base theory, dipole-dipole interactions, highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) interactions, hydrogen bonding, gibbs free energy of bonding, etc.). Typical depressants in froth flotation processes for the enrichment of metal ores, such as guar gum, are not used as dewatering agents, or even as depressants in bitumen separation flotation processes. Furthermore, in both applications described below (waste clay and coal dewatering), no reagents are currently used to improve the solid/liquid separation. In general, despite the large amounts of flotation depressants and dewatering agents provided in the art, it is still difficult in many cases to obtain an appropriate degree of purification. There is therefore a need in the art for reagents that can be effectively used in a wide range of separation processes, including both froth flotation and the separation of solid contaminants from liquid suspensions.

Other methods of separation

In addition to froth flotation, other methods for separating solid contaminants from liquid suspensions may include the use of additives that destabilize the suspensions or also bind the contaminants into larger agglomerates. For example, agglomeration refers to the destabilization of suspended solid particles by neutralizing the charge separating the suspended solid particles. Flocculation refers to bridging or aggregation of solid particles into clumps or floes, thereby facilitating their separation by settling or flocculation, depending on the density of the floe relative to the liquid. In addition, filtration can be used as a means of separating larger floes.

The additives described above, and especially flocculants, are often used, for example, to separate solid particles of rock or drill cuttings from oil and gas well drilling fluids. These drilling fluids (commonly referred to as "drilling mud") are important in the drilling process for several reasons, including cooling and lubrication of the drill bit, establishing a fluid backpressure to prevent fluids formed of high pressure oil, gas, and/or water from prematurely entering the well, and to resist collapse of the open hole wellbore. Drilling mud, whether water or oil based, also removes drill cuttings from the drilling area and transports them to the surface. Flocculants, such as acrylic acid polymers, are commonly used to collect these debris on the surface of the circulating drilling mud where they can be separated from the drilling mud.

Other uses of flocculants in solid/liquid separation include the aggregation of clays suspended in the bulk waste slurry effluent from phosphate production plants. Flocculants, such as anionic natural or synthetic polymers (which may be combined with a fibrous material, such as recycled newspaper) are often used for this purpose. The aqueous clay slurry formed in the phosphate purification plant typically has a flow rate of greater than 100,000 gallons per minute and generally includes less than 5% solids by weight. The dehydration of such waste clays (e.g. by settling or filtration) allows the recycling of water, presenting one of the most difficult problems associated with recovery. Settling ponds used for such dewatering typically account for about half of the mine area, and dewatering times can be on the order of months to years.

Other industrial importance in the separation of solids from aqueous liquids includes the filtration of coal from aqueous slurries (i.e., slurry dewatering), the treatment of sewage to remove contaminants such as sludge by sedimentation, and the treatment of pulp and paper mill effluents to remove suspended cellulosic solids. Dehydration of coal presents a significant problem in the industry because the BTU value of coal decreases with increasing water content. Untreated sewage, industrial and municipal, requires significant treatment capacity because, for example, waste generated by the U.S. population is collected in the sewage system and carries about 140 billion gallons of water per day. The paper industry effluent stream also represents a large volume of solids-containing aqueous liquor, since the wastewater produced by a typical paper mill often exceeds 2.5 million gallons per day. The removal of sand from bitumen-containing aqueous slurries produced in the extraction and subsequent processing of oil sands, as previously described, presents another commercially significant challenge in the purification of aqueous liquid suspensions. Also, the removal of suspended solid particles is often an important consideration in the purification of water, for example in the preparation of potable (i.e., potable) water. Synthetic polyacrylamides are flocculants for this application, as well as naturally occurring hydrocolloid polysaccharides such as alginate esters (copolymers of D-mannuronic acid and L-guluronic acid) and guar gum.

Thus, the above applications provide several specific examples relating to the treatment of aqueous slurries to remove solid particles. However, such separations are common in a number of other processes in the mineral, chemical, industrial and municipal waste, sewage treatment and paper industry, as well as in a wide range of other water-consuming industries. Accordingly, there is a need in the art for an additive that can effectively promote the selective separation of a large number of solid contaminants from a liquid suspension. Advantageously, these agents should be selective in chemically interacting with solid contaminants through coagulation, flocculation or other mechanisms so that removal of these contaminants is easily accomplished. Particularly desirable are additives that are also capable of complexing unwanted ionic species (such as metal cations) so as to also facilitate their removal.

Summary of The Invention

All purpose

Aspects of the present invention are described in US patent nos. 5,362,842, 5,389,716, 5,674,971, and 6,114,491, each of which is incorporated herein by reference in its entirety.

The present invention is directed to amine-aldehyde resins for the generally selective removal of a wide variety of solid and/or ionic species from a liquid in which they are suspended and/or dissolved. These resins are highly versatile, as they are particularly useful as froth flotation depressants for separating bitumen from sand and/or clay, or for purifying clay (e.g., kaolin) from clay-containing ores. These amine-aldehyde resins are also useful for treating aqueous liquid suspensions (e.g., aqueous suspensions containing sand, clay, and/or other solids, such as suspensions of used drilling cutting fluids, as well as treatment and effluent streams in phosphate and coal production, sewage treatment, paper making, or asphalt recovery equipment) to remove solid particles and also potential metal cations (e.g., in the purification of drinking water).

Froth flotation process

Without being limited by theory, the amine-aldehyde resins of the present invention are highly selective in the froth flotation process: including those used for (1) bonding to sand and/or clay to purify bitumen and (2) purifying clay-containing ores, as well as those for various valuable mineral or metal purification or enrichment processes, such as coal ore or synthetic gypsum enrichment. And these resins have an affinity for water, sand, clay, and/or ash particles that interact with and bind to the resin, are effectively separated in the aqueous phase in a froth flotation process. As a result, sand, clay, ash, and/or other contaminants (e.g., gypsum material) can be selectively separated from valuable materials (e.g., minerals, metals, or bitumen). Additionally, the clay may be enriched using a froth flotation process to remove impurities, such as iron oxide, from the clay-containing ore.

Accordingly, in one embodiment, the present invention is a process for purifying bitumen from a bitumen-containing slurry comprising sand or clay. The method includes treating the slurry with a depressant comprising a resin including the reaction product of a primary or secondary amine and an aldehyde and recovering purified bitumen having a reduced amount of sand or clay by froth flotation either after the treating step or in the process. In another embodiment, the resin is a urea-formaldehyde resin, which is typically the reaction product of urea and formaldehyde in a formaldehyde to urea (F: U) molar ratio of from about 1.75: 1 to about 3: 1. In another embodiment, the depressant includes a resin in a solution or suspension having a solids content of from about 30% to about 90% by weight.

In another embodiment, the invention is a process for purifying clay from a clay-containing ore comprising an impurity selected from the group consisting of: a metal, a metal oxide, a mineral, and mixtures thereof. The method comprises treating a slurry of the clay-containing ore with a depressant comprising a resin, and recovering purified clay having a reduced amount of at least one impurity by froth flotation after or during the treating step. The resin is the reaction product of a primary or amine and an aldehyde (i.e., an amine-aldehyde resin). In another embodiment of the invention, the clay-containing ore comprises kaolin clay. In another embodiment, the impurity comprises a mixture of iron oxide and titanium dioxide. In another embodiment, the impurities comprise coal.

In another embodiment, the invention is a process for enriching an ore. The method includes treating a slurry of ore particles with a depressant containing an amine-aldehyde resin. The ore slurry treatment may take place before or during froth flotation. In another embodiment, when the treatment of the ore slurry occurs prior to froth flotation, the treating step comprises combining the ore slurry with the depressant followed by flotation of the ore slurry and the depressant. In another embodiment, the treating step further comprises conditioning the slurry after the combining step and before froth flotation. The conditioning step may be carried out in a conditioning vessel at a conditioning temperature of from 1 ℃ to about 95 ℃ and at a conditioning pH of at least about 2.0 for a conditioning time of from about 30 seconds to about 10 minutes. In another embodiment, the beneficiation process purifies and recovers a valuable mineral or metal from ore, selected from the group consisting of: phosphates, potash, lime, sulfates, gypsum, iron, platinum, gold, palladium, titanium, molybdenum, copper, uranium, chromium, tungsten, manganese, magnesium, lead, zinc, clay, coal, silver, graphite, nickel, bauxite, borax, and borates. In another embodiment, the ore includes an impurity selected from the group consisting of: sand, clay, an iron oxide, a titanium oxide, iron-bearing titanium dioxide, mica, ilmenite, tourmaline, an aluminum silicate, calcite, dolomite, anhydrite, an iron magnesium mineral, feldspar, calcium magnesium carbonate, igneous rock, soil, and mixtures thereof. Often, these impurities are sand or clay impurities, such as impurities typically extracted with phosphate or potassium ores. However, in another embodiment, mercury is an impurity in the ore, including coal or synthetic gypsum, which is treated with an amine-aldehyde resin prior to or during a froth flotation step. The coal or synthetic gypsum has an initial amount of total mercury and the enriching purifies and recovers from the ore purified coal or purified synthetic gypsum having a final amount of total mercury that is less than the initial amount of total mercury, wherein the initial and final amounts of total mercury are measured on a volatile-free basis. In another embodiment, the total mercury final amount is less than about 10ppb on a volatile-free basis. In another embodiment, the synthetic gypsum is formed in the desulfurization of flue gas from a coal-fired power plant. In another embodiment, the depressant includes an amine-aldehyde resin and a chelating agent. In another embodiment, the ore comprises an impure coal ore, the processing step is prior to or during the froth flotation step and the enriching purifies and recovers from the impure coal ore a purified coal having a reduced amount of impurities relative to the impure coal ore, the impurities selected from the group consisting of: nitrogen, sulfur, silicon, ash, and pyrite, wherein the impurities are measured on a volatile-free weight basis. In another embodiment, the ore comprises an impure coal ore, the processing step is prior to or during a froth flotation step, and the enriching purifies and recovers purified coal having a reduced amount of moisture and/or an increased BTU value per unit weight relative to the impure coal ore.

Other methods of separation

In another embodiment, the invention is a method for purifying an aqueous liquid suspension comprising a solid contaminant. The method comprises treating the liquid suspension with the resin described above and removing (1) at least a portion of the solid contaminants in the contaminant-enriched fraction and/or (2) a purified liquid after or during the treating step. In another embodiment, the treating step comprises flocculating the solid contaminant (e.g., sand or clay). In another embodiment, the removing step is performed by sedimentation, flotation or filtration. In another embodiment, the liquid suspension is an oil well drilling fluid and the method comprises removing the purified drilling fluid for reuse in oil well drilling. In another embodiment, the aqueous liquid suspension is a clay-containing effluent slurry from a phosphate production facility and the process includes removing the purified water for reuse in phosphate production. In another embodiment, the aqueous liquid suspension is an aqueous coal-containing suspension and the process comprises removing a coal-rich fraction by filtration. In another embodiment, the aqueous liquid suspension comprises sewage and the method comprises removing the purified water by sedimentation. In another embodiment, the aqueous liquid suspension comprises a pulp or paper mill discharge, the solid contaminant comprises a cellulosic material and the method comprises removing purified water. In another embodiment, the aqueous liquid suspension is a bitumen production process intermediate or effluent slurry comprising sand or clay. In yet another embodiment, the purified liquid is potable water.

In another embodiment, the invention is a process for purifying coal ore. The method includes treating an aqueous slurry of the coal mine stone with a depressant before or during a size or density classification operation, which recovers purified coal having a reduced amount of impurities relative to the coal mine stone, the impurities selected from the group consisting of: mercury, nitrogen, sulfur, silicon, ash, and pyrite, wherein the impurities are measured on a volatile-free basis. The depressant includes an amine-aldehyde resin as described herein. In another embodiment, the purified coal has a reduced amount of moisture and/or an increased BTU to/unit weight relative to the coal mine rock. In another embodiment, the purified coal has a reduced amount of all impurities relative to the coal mine stone selected from the group consisting of: mercury, nitrogen, sulfur, silicon, ash, and pyrite. In another embodiment, the reduced amount is less than the amount of a purified reference coal recovered in a size classification operation, but without treating the aqueous slurry with a depressant. In another embodiment, the size or density classification operation is selected from the group consisting of: cyclonic separation, dense medium separation, filtration, screening and combinations thereof.

In another embodiment, the invention is a method for purifying water comprising a metal cation. The method includes treating the water with the resin described above and recovering at least a portion of the metal cations by filtration to produce purified water (e.g., potable water). In another embodiment, the removing step comprises membrane filtration. In another embodiment, the metal cation is selected from the group consisting of: as⁺⁵、Pb⁺²、Cd⁺²、Cu⁺²、Mn⁺²、Hg⁺²、Zn⁺²、Fe⁺²And mixtures thereof. In yet another embodiment, the resin is modified with an anionic functional group.

These and other embodiments will be apparent from the detailed description below.

Brief description of the drawings

Figure 1 is a photograph of four bottles containing graphite (two bottles on the left) and bentonite (two bottles on the right), which were kept for 24 hours after vigorous shaking to suspend the solids in water. The leftmost bottle and the third bottle from the left were treated with urea formaldehyde resin before shaking.

Detailed description of the invention

All purpose

The resin used in the separation process of the present invention is the reaction product of a primary or secondary amine and an aldehyde. The primary or secondary amine is capable of reacting with an aldehyde by virtue of having a nitrogen atom that is not fully substituted (i.e., it is not part of a tertiary or quaternary amine) to form an adduct. For example, if formaldehyde is used as the aldehyde, the adduct is a methylolated adduct having reactive methylol functionality. For purposes of the present invention, representative primary and secondary amines used to form the resin include compounds having at least two functional amine or amide groups or amidine compounds having at least one of each of these groups. These compounds include urea, guanidine and melamine, which may be substituted on the corresponding amine nitrogen with aliphatic or aromatic groups, at least two of which are not completely substituted. Often primary amines are used. Urea is representative of these due to its low cost and wide commercial availability. In the case of ureas, at least a portion of them can be substituted, if desired, with ammonia, primary alkylamines, alkanolamines, polyamines (e.g., alkyl primary diamines such as ethylenediamine, and alkyl primary triamines such as diethylenetriamine), polyalkanolamines, melamines or other amine-substituted triazines, dicyandiamides, substituted or cyclic ureas (e.g., ethylene urea), primary, secondary and alkylamine, tertiary amine and alkylamine, guanidine, and guanidine derivatives (e.g., cyanoguanidine and acetylguanidine). Ammonium sulfate, cyclic phosphates, as well as cyclic phosphates, formic acid or other organic acids may also be used in combination with urea. The amount of these components (or their combined amount if used in combination), if combined into a resin to replace the urea moiety, will typically vary from about 0.05 to about 20% by weight of the resin solids. As understood by those skilled in the art, these types of agents promote hydrolysis resistance, flexibility, reduced aldehyde emissions, and other characteristics.

As described above, the aldehydes used to form the resin with the primary or secondary amines can be formaldehyde, or other aliphatic aldehydes, such as acetaldehyde and propionaldehyde. The aldehydes also include aromatic aldehydes (e.g., benzaldehyde and furfural), and other aldehydes such as aldol, glyoxal, and crotonaldehyde. Mixtures of aldehydes may also be used. Generally, due to its commercial availability and relatively low cost, formaldehyde is used.

In the formation of resins, the initial formation of an adduct between an amine and an aldehyde is known in the art. The rate of aldehyde addition reaction generally depends to a high degree on the pH and the degree of substitution achieved. For example, the addition of formaldehyde to urea in a three-position ratio of 9: 3: 1 has been estimated to form one, two, and three hydroxymethyl groups in sequence, whereas tetramethylol urea is generally not produced in significant amounts. The adduct-forming reaction is typically carried out at an advantageous rate under basic conditions and thus in the presence of a suitable basic catalyst (e.g., ammonia, an alkali metal hydroxide or an alkaline earth metal hydroxide). Sodium hydroxide is most widely used.

At sufficiently high pH values, it is possible for the adduct-forming reaction to proceed substantially in the absence of condensation reactions that increase resin molecular weight (i.e., they build up the resin) through polymerization. However, for further reaction from the amine aldehyde adduct to form the low molecular weight condensate resin, the reaction mixture is generally maintained at a pH typically from about 5 to about 9. If desired, an acid such as acetic acid may be added to help control the pH and hence the rate of condensation reaction and the molecular weight of the final condensation resin. The reaction temperature is generally in the range of from about 30C to about 120C, typically less than about 85C, and reflux temperature is often used. In the preparation of low molecules from primary or secondary amines and aldehyde starting materialsIn the amount of amine aldehyde condensate resin, a reaction time of from about 15 minutes to about 3 hours, and typically from about 30 minutes to about 2 hours, is used. Various additives may be incorporated before or during the condensation reaction to impart the desired properties to the amine-aldehyde resin. For example, guar gum; carboxymethyl cellulose or other polysaccharides, such as alginates; or polyols, e.g. polyvinyl alcohol, pentaerythritol or Jeffol^TMPolyols (huntman Corporation, Salt Lake City, Utah, USA) can be used to modify the viscosity and consistency of the final amine-aldehyde resin and improve its performance in froth flotation as well as other applications. In addition, quaternary ammonium salts, including diallyldimethylammonium chloride (or the like, such as diallyldiethylammonium chloride) or alkylating agents including epichlorohydrin (or the like, such as epibromohydrin) can be used to increase the cationic charge of the amine-aldehyde resin and thus improve its performance in certain solid/liquid separations (e.g., clay dehydration) discussed below. In this way, the additives can be more efficiently reacted into the amine-aldehyde resin rather than merely being blended with the resin after it is prepared.

In one aspect of the invention, the following example of a base urea-formaldehyde resin is provided. In the first reaction step, formaldehyde (F), urea (U), Triethanolamine (TEA) and optionally ammonia are fed into a reaction vessel. The reactants can be introduced into the reactor in any conventional manner or sequence. The amount of each reactant added to the reactor is an amount sufficient to achieve a molar ratio of F/U/TEA/ammonia in the range of (1.50: 4.0) to 1 (0.001-0.1) to (0.0-0.5). Each reactant can be introduced in one or more charges. It is preferred that the amount of each reactant be sufficient to maintain the molar ratio of F/U/TEA/ammonia during the first reaction step in the range of (1.50-4.0) to 1 (0.001-0.1) to (0.0-0.5). The present invention relates to resin compositions comprising low temperature curable functionalized unsaturated polyesters, coating compositions comprising the resins, and methods of producing the same.

The pH of the reaction mixture is maintained above about 7, preferably above about 8, as measured at the reaction temperature at the start of the reaction. During the first reaction step, the pH typically stays above about 7. The alkaline reaction mixture is heated to a temperature of at least about 70 c, preferably above about 80 c, and most preferably to a temperature of about 95 c. Generally, the reaction mixture is heated to about 95 ℃ over a period of about 30 minutes. The reaction mixture is maintained at an elevated temperature for a period of time sufficient to ensure complete methylolation of the urea in a controlled time frame. In general, 15 to 20 minutes at about 95 ℃ is sufficient.

In the second reaction step, a mineral or organic acid is added to the reaction mixture in an amount sufficient to achieve an acidic pH condition in the reactant mass, preferably a pH of about 5. The acid can be added in a single addition or in multiple additions. The reaction is then continued under such acidic conditions at an elevated temperature, typically above about 75 c, for a period of time sufficient to reduce the free formaldehyde to less than 2%, preferably less than 1%, generally about 45 to 240 minutes, preferably about 90 to 120 minutes. A reaction temperature of about 95 c is suitable for about two hours. Depending on the initial F: U molar ratio, the urea addition and reaction is repeated further until the F/U molar ratio is reduced to between about 1.5: 1 and 2.5: 1. It is important to maintain the pH at about 5 upon any addition of these additional ureas to achieve the desired resin characteristics. For example, after the initial second reaction step, the reaction mixture is then cooled to, for example, about 80 ℃ and additional urea is added and the reaction is continued for about another hour. Multiple urea addition/reaction steps may be used until the desired final F/U molar ratio is obtained.

Additional triethanolamine may be added if desired. The resin is then cooled to ambient temperature and neutralization can be carried out, for example by quenching the reaction by adding sodium hydroxide.

Those skilled in the art recognize that these reactants are commercially available in a variety of forms. Any form that can react with other reactants and does not introduce extraneous moieties deleterious to the desired reaction and reaction product can be used to prepare the urea-formaldehyde resins of the present invention.

Urea is available in many forms. Paraformaldehyde (solid, polymerized formaldehyde) and formalin solutions (aqueous solutions of formaldehyde, often containing methanol, with a formaldehyde concentration of 37%, 44%, or 50%) are commonly used forms. Formaldehyde can also be obtained as a gas. Any of these forms is suitable for use in the operation of the present invention. Typically, formalin solutions are preferred as the formaldehyde source.

Similarly, urea is available in many forms. Solid urea (e.g., prill), and urea solutions (typically aqueous solutions) are commonly available. In addition, urea can be combined with another moiety (most typically formaldehyde and urea-formaldehyde), often in aqueous solution. Any form of urea or urea combined with formaldehyde is suitable for use in the practice of the present invention. Urea prills and combined urea-formaldehyde products such as urea-formaldehyde concentrates or UFC 85 are preferred. These types of products are disclosed in U.S. Pat. nos. 5,362,842 and 5,389,716.

TEA is typically supplied as a liquid, often in combination with diethanolamine and monoethanolamine. Although any TEA form is suitable for use in the claimed process and product, it is preferred to use a TEA product with only minimal diethanolamine and monoethanolamine contaminants. Preferably, the TEA weight concentration is at least about 10 times the sum of the weight concentrations of the diethanolamine and monoethanolamine, and more preferably about 20 times the sum.

It is also well recognized by those skilled in the art that ammonia is available in a variety of gaseous or liquid forms, including in particular aqueous solutions at various concentrations. Any of these forms is suitable for use. However, preferred here are commercially available aqueous ammoniacal solutions. Such solutions typically contain between about 10 and 35 percent ammonia. If stability and control issues can be overcome, a solution with 35% ammonia can be used. Aqueous solutions containing about 28 percent ammonia are particularly preferred. Anhydrous ammonia may also be used.

The use of ammonia and/or the subsequent addition of urea is a commonly used prior art technique to reduce the level of free formaldehyde in urea-formaldehyde polymer systems. The former technique suffers from the problem of reducing the hydrolysis resistance of the cured polymer. The latter technique suffers from one tendency to produce polymeric systems that release smoke during the curing cycle. The present invention is not subject to either of these two problems, but rather significantly reduces the level of free formaldehyde during curing and in the cured product.

The use of a scavenger converts the formaldehyde from free formaldehyde to a pH labile monomer that decomposes over time under acidic conditions to release formaldehyde. It has been found that the polymers of the present invention are more pH stable and release significantly less formaldehyde when exposed to an acidic environment than polymers synthesized in the absence of a small modifying amount of triethanolamine. This property makes the resin particularly useful as a binder for metal salts (particularly metal acid salts) in the preparation of briquettes for deodorizing animal waste water, as such products are exposed to acidic hydrogen sulfide evolved from the waste.

In one aspect of the invention, an amount of urea and formaldehyde, if desired, fresh water, is fed to a stainless steel reactor equipped with a stirrer in an amount to provide an initial formaldehyde to urea molar ratio of between about 1.50 and 4.0, preferably between 2.75 and 4.0. TEA was then added in amounts to provide a TEA to urea molar ratio between 0.001: 1 and 0.10: 1, the reaction was mixed and the pH recorded. The pH should preferably be between about 8.0 and about 8.4, more preferably about 8.2.

In a preferred operation of the invention, ammonium hydroxide is then fed to the reactor in an amount to provide a molar ratio of ammonia to urea of about 0.2: 1.0 to 0.5: 1.0. Ammonium hydroxide is added as rapidly as possible, preferably within 25 minutes or less.

Under standard conditions, the addition of ammonium hydroxide causes the temperature of the reactant mass to exotherm to 70 ℃ to 75 ℃. The temperature was then maintained at a minimum temperature of 75 ℃ and at 75 ℃ to 80 ℃ for a minimum time of 5 minutes. During this 5 minute hold, the pH was checked. A pH between about 7.8 and 8.5 is desirable. If the solution is above 8.5, then 7.0% sulfuric acid is used to adjust down to the desired range.

The temperature is then cooled to below about 70 c, preferably below about 45 c. When the temperature is at or below 50 ℃, urea is added as rapidly as possible so as to bring the reaction mixture within the above-mentioned molar ratio range. The addition of urea causes the reaction mixture to become endothermic and aids in this cooling.

Starting at about 40 ℃, the reaction mixture was heated to about 95 ℃ over the course of 30 minutes. The exotherm of the reaction contributes to the temperature rise. Heating may be controlled by vacuum and/or by cooling coils. During the warming cycle, the pH will drop. It is very important to monitor the pH every 10 minutes during the warming cycle. The reaction mixture is maintained at 95 ℃ for 15 to 20 minutes, during which time the pH should be stabilized between about 6.8 and 7.3. If the pH drops too quickly, the pH during the acid condensation step will be lower and the resin build up faster. To control build-up of the resin, the pH may be increased by adding a base or alternatively, the reaction temperature may be lowered.

A 7.0% sulfuric acid solution was then added over a period of 10 minutes. The addition of sulfuric acid must be accomplished in a zone of mixing below the surface of the resin so that the dispersion is very rapid and does not form gelled particles. During the next hour, the pH of the reactant mass will decrease to about 4.9 to about 5.2. If the pH is allowed to stabilize above 5.2, resin build-up is hindered. Thus, an additional small amount of 7.0% sulfuric acid may be required to bring the pH in the desired range of 4.9 to 5.2. However, care must be taken if the pH drops below 4.9 because the rate of resin build-up increases rapidly with decreasing pH. If the pH is lowered below 4.9, 25-50% aqueous sodium hydroxide may be used to raise the pH to a range of 4.9-5.2 or to lower the temperature, e.g., to 90 ℃ or less, to maintain control of resin build-up (resin advancement). Once the desired viscosity is reached, the reactants are cooled to 80 ℃, which reduces the rate of viscosity build. More urea is then added to reduce the cumulative F: U molar ratio to the desired level and the reactant mass is allowed to react at 80 ℃ for 40-60 minutes to maintain a sufficient ramp rate. If the rate of advancement slows down, the temperature should be increased. It is not necessary or even desirable to add more acid to lower the pH. At this stage, generally only the temperature should be used to control the rate of advancement. An increase of 5c doubles the rate of gain. A reduction of 5c will cut the rate of gain. However, the temperature should be allowed to fall below 78 ℃ typically during resin build up.

It should be understood that the addition of a single hypourea in the second reaction stage, as described herein, may be sufficient to obtain the desired molar ratio and resin characteristics. However, two, three or even four or more urea loadings can also be used. The number of urea additions and the amount of urea added depends on the desired resin characteristics, including the molar ratio of formaldehyde to urea, viscosity, desired solubility, and cure rate, and will be readily determinable by one of skill in the art using routine experimentation within the parameters taught herein. Additional TEA addition can also be used. Additional modifiers such as melamine, ethylene urea, and dicyandiamide (dyaniamide) may be incorporated into the resin of the present invention. It is also possible to use additional urea additions for the purpose of removing formaldehyde or as a diluent.

Another aspect of the present invention is based on the discovery that: a prepolymer formed by the first reaction step of formaldehyde, urea and ammonia can be converted into a crosslinked polymer matrix that exhibits improved control over formaldehyde emissions and faster cure rates than similar polymers produced using conventional methods. The polymer is prepared by reacting urea with formaldehyde in at least one two-step and optionally one three-step process.

In this regard, for example, in the first step, a cyclic triazinone/triazine polymer is formed. Urea and formaldehyde are mixed in the presence of ammonia under basic reaction conditions at a F/U molar ratio of between about 1.2: 1 and 1.8: 1. The ammonia is provided in an amount sufficient to produce an ammonia to urea molar ratio of between about 0.05: 1 and 1.2: 1, preferably between about 0.2: 1 and 0.8: 1. The alkalinity of the reaction mixture is maintained at a pH of about 8.0 to 10.0, preferably about 8.7 to 9.3. The basicity can be maintained by the addition of an alkali metal hydroxide, such as sodium, lithium, or potassium hydroxide, preferably sodium hydroxide or other compounds such as alkali metal carbonates, alkaline earth metal hydroxides, organic amines.

The mixture is rapidly heated to a temperature of about 85 ℃ to 105 ℃, preferably about 95 ℃, and the mixture is held at this temperature for a period of time sufficient to react to form the cyclic triazinone/triazine polymer. The amount of time sufficient to allow the reaction to proceed to the desired extent varies depending on the particular reaction conditions, but is typically about 45 to 135 minutes and especially about 90 minutes.

In the second step, a thermoset polymer is formed from the cyclic polymer. The reaction mixture comprising the triazinone/triazine polymer formed in step one is cooled to a temperature of between about 60 ℃ and 90 ℃, preferably about 85 ℃, and then additional formaldehyde is added, preferably with additional urea, to produce a higher cumulative F/U molar ratio of between about 1.5: 1 and 3.0: 1, preferably between about 1.9: 1 and 2.7: 1. Sufficient mild acid is also added to adjust the pH to a value low enough to allow better control of the rate of condensation reaction, wherein the pH is preferably about 6.0 to 6.4. Mild acids include a dilute mineral acid, an organic acid or an acid salt, such as ammonium chloride, ammonium sulfate, etc., or dilute to a controlled concentration and alum for pH adjustment may be added before or after formaldehyde. The reaction is then allowed to continue under this mildly acidic condition at a temperature between 70 ℃ and 105 ℃, preferably about 85 ℃ for a period of time sufficient to form a thermoset polymer. A typical but not limiting reaction time is about 10 to 90 minutes, most often about 45 minutes, to ensure proper enhancement of the polymer condensation reaction.

The polymer is then cooled to a suitable temperature, for example to a temperature of about 80 ℃. The polymer may be cooled in multiple stages, for example the polymer may be cooled first to about 80 ℃ and then to about 75 ℃ over about 15 minutes. The cooling time as well as the temperature can be varied and the selection of specific conditions is within the scope of the art by routine experimentation. As the polymer cools, the pH decreases to about 4.3 to 4.9, preferably about 4.5 and the viscosity of the polymer increases. Once the desired viscosity is reached, for example 100 to 225 centipoise, the mixture is cooled to room temperature. The resin can be used quickly or further processed and stored.

If the resin is not used immediately, a third neutralization step may be used. In this step, the resin is neutralized, for example, with an alkali metal hydroxide, such as sodium, lithium, or potassium hydroxide, preferably sodium hydroxide, to enhance its storage stability. Other neutralizing agents include alkali metal carbonates, alkaline earth metal hydroxides, and organic amines.

These reactants may also include small amounts of resin modifiers such as Ethylenediamine (EDA). Additional modifiers, such as melamine, ethylene urea, and primary and secondary and triamines (e.g., dicyandiamide) can also be incorporated into the resins of the present invention. The concentration of these modifiers in the reaction mixture can vary from 0.05% to 5.00%. These types of modifiers promote hydrolysis resistance, polymer flexibility, and lower formaldehyde emissions.

A cyclic urea prepolymer is then used as a modifier for the resin. The modifier level reported as a percentage of binder solids using the cyclic urea prepolymer is preferably from 1% to 95%, although larger amounts are also contemplated. Binder solids refers to the percent of phenolic resin solids plus the percent of modifier solids. Thus, typically the resin is combined with a cyclic urea prepolymer to obtain 5 to 99 wt% resin solids and 1 to 95 wt% cyclic urea prepolymer solids. The preferred range depends on the application.

Although generally not required, additional urea may also be added for formaldehyde removal purposes or as a diluent.

The resins of the present invention are also advantageously used in the preparation of glass fiber mats to be used, for example in the manufacture of roof shingles. In this aspect, a glass fiber mat is applied to the mat and the incorporated binder resin is cured prior to passing the mat through a drying oven in which the mat is dried. The glass fiber mats so produced with the resins of the present invention exhibit, among other things, low formaldehyde emissions. The low formaldehyde emission of these resins is a useful aspect of these resins for the applications disclosed herein.

The condensation reaction products of the amine aldehyde, amide aldehyde, and/or amidine aldehyde adduct products described above include, for example, those obtained from the formation of: (i) bridging by an alkylene group between the reactive amido nitrogen of an alkyl alcohol and an amino group, (ii) linking by an alkylene ether of two alkyl alcohol group reactions, (iii) alkylene linking from alkylene ether linking wherein formaldehyde is subsequently removed, and (iv) alkylene linking from an alkyl alcohol group wherein water and formaldehyde are subsequently removed.

In general, the molar ratio of aldehyde to primary/or secondary amine in the preparation of the resin is from about 1.5: 1 to about 4: 1, which refers to the ratio of the moles of all aldehydes to the moles of all amines, amides, and amidines reacted during the adduct formation and condensation reactions described above (whether conducted separately or simultaneously) to prepare the resin. The resin is typically prepared at ambient pressure. The viscosity of the reaction mixture is often used as a convenient proxy for the molecular weight of the resin. The condensation reaction can therefore be stopped when the desired viscosity is obtained after a sufficiently long time and at a sufficiently high temperature. At this point, the reaction mixture may be cooled and neutralized. Water may be removed by vacuum distillation to produce a resin with the desired solids content. Any of a wide variety of conventional procedures for reacting primary and secondary amines with aldehyde components may be used, such as staged monomer addition, staged catalyst addition, pH control, amine modification, and the like, and the invention is not limited to any particular procedure.

One representative amine-aldehyde resin used in the separation process of the present invention is a urea-formaldehyde resin. As described above, a portion of the urea can be replaced with other reactive amines and/or amides and a portion of the formaldehyde can be replaced with other aldehydes to provide different desired characteristics without detracting from the characteristics of the resin as a urea-formaldehyde resin. Urea-formaldehyde resins can be prepared from urea and formaldehyde monomers or from precondensates in a manner known in the art. Typically, the urea and formaldehyde are reacted at a formaldehyde to urea (F: U) molar ratio in the range of from about 1.75: 1 to about 3: 1, and often at a formaldehyde to urea (F: U) molar ratio in the range of from about 2: 1 to about 3: 1, to provide species that are sufficiently methylolated for resin crosslinking (e.g., di-and tri-methylolated ureas). Generally, the urea-formaldehyde resin is a highly water-dilutable dispersion, if not an aqueous solution.

Other suitable amine-aldehyde resins useful in the present invention include those having utility as binders for glass mats, as disclosed in U.S. Pat. No. 5,389,716. In this regard, the aldehyde condensation polymer to latex weight ratio is greater than or equal to 1: 1 on a volatile free basis in the adhesive composition, as disclosed, for example, in U.S. Pat. No. 5,389,716. Thus, the weight of the latex based on the latex and the aldehyde condensation polymer ranges from 50 to about 95 percent by weight and the aldehyde condensation polymer ranges from about 5 to 50 percent by weight. In a preferred embodiment, the silica colloid ranges from about 0.1% to about 10% by weight based on the weight of the resin (aldehyde condensation polymer) on a volatile-free basis. In another preferred embodiment, the aldehyde condensation polymer is a modified urea-formaldehyde condensate and the silica colloid ranges from 0 to about 10% by weight based on resin on a volatile-free basis.

Many of the aldehyde condensation polymers of phenol, resorcinol, urea, and melamine have been widely used as additives and their properties are well known. Aldehyde condensation polymers that can be used in the present invention have reactive alkyl alcohol groups and are well known and commercially available. These polymers may be cationic, anionic or nonionic, preferably nonionic. As noted earlier, one critical constraint is the compatibility of the resin with the latex. In this context, compatibility refers to the ability to mix together the latex and resin by precipitation or coagulation without the formation of premature solids. As used herein, "polymer" refers to a mixture of resins that do not crystallize or have a distinct melting point. In particular, preferred polymers are those having "reactive alkyl alcohol groups" capable of reacting with ammonia or an amine used in the present invention to modify the aldehyde condensation polymer. As used herein, "condensation reaction" refers to a polymerization reaction in which a molecule, such as water, is eliminated and distinguished from an "addition reaction" in which no by-product is formed. Furthermore, the aldehyde condensation polymers used in the present invention exclude those having a predominance of amide-forming substituents.

Three types of polymers may also be preferred: phenolics, aminoplasts, and ketone-aldehyde condensation polymers. They include, for example, acid-or base-catalyzed phenol-aldehyde resins, urea-aldehyde resins, melamine-aldehyde resins, acetone-aldehyde resins, and the like. The following references, cited in US patent No. 3,896,081, disclose methods for preparing condensation resins useful in the present invention: "the chemistry of Synthetic Resins" by Carleton Ellis, Reinhold publishing Co., 1935; "Phenolic Resin Chemistry" by N.J.L.Megson, Academic Press Inc., New York, 1958; "Aminoplasts" by C.P.Vale, Cleaver-Hume Press Ltd., London, England; and british patent No. 480,316. See also US patent No. 4,794,051 (phenolics) and US patent No. 4,169,914 (aminoplasts).

Specifically, aldehyde condensation polymers that can be used include (1) phenolics comprising condensation polymers of an aldehyde (such as formaldehyde) with a phenolic material having at least two positions ortho and/or para to the hydroxyl group open for reaction, such as phenol, phenol-toludiol, cresol, resorcinol, and derivatives thereof, (2) aminoplasts comprising condensation polymers of an aldehyde (such as formaldehyde) with compounds such as phenyl guanamine, dicyandiamide, urea, melamine-urea, melamine and derivatives thereof, and (3) ketone-aldehyde condensation polymers such as acetone-formaldehyde, methyl ethyl ketone formaldehyde, methyl isobutyl ketone formaldehyde, and the like. Especially if the free monomer formula is less than 2 percent. Phenolic novolacs, because they lack reactive alkyl alcohol groups and lack water solubility, are not directly useful in the present invention; they can be further reacted with aldehydes to convert them into useful resole resins. Each of the aldehyde condensation polymers mentioned above is prepared by known methods and maintained under conditions which prevent it from condensing to an insoluble state.

The aldehyde used in the preparation of the condensation polymer may be (1) monofunctional (i.e., a single aldehyde) or (2) multifunctional, having at least two aldehyde groups separated by at most one carbon atom and may be, for example, formaldehyde, paraformaldehyde, polyoxymethylene, trioxane, acrolein, and aliphatic or cyclic aldehydes such as glyoxal, acetaldehyde, propionaldehyde, butyraldehyde, and furfural. When formaldehyde, furfural, paraformaldehyde, polyoxymethylene or trioxane is used, the condensation reaction is generally accomplished using a mild acid, base or no catalyst. When acrolein, glyoxal, acetaldehyde, propionaldehyde, or butyraldehyde is used, the condensation reaction is generally accomplished by combining the reactants in the presence of a strong acid catalyst and neutralizing the reaction product, adding more aldehyde (aidehydee) and further in the presence of a mild acid or base, catalyst. See generally US patent No. 3,896,081.

The aldehyde series mentioned aboveCondensation polymer may be modified by reacting the condensation reactant during or after the condensation reaction with ammonia, preferably aqueous ammonia or a primary polyamine, preferably a primary diamine, to obtain a modified aldehyde condensation polymer. An example of the latter is disclosed in US patent No. 3,896,081 to Baxter et al, which is incorporated herein by reference. Preferably, the modified aldehyde condensation polymer is prepared by reacting the condensation reactant with ammonia or a primary polyamine, preferably an alkyl primary diamine, more preferably a C₁-C₆Alkyl primary diamines such as ethylene diamine. The ammonia may be aqueous ammonia or anhydrous ammonia.

The resin based on the aldehyde condensation polymer of the binder combination may also be a commercially available material such as urea formaldehyde resin, for example of the type sold by Georgia Pacific Resins, inc., Atlanta, Ga, (e.g., GP-2904 and GP-2914), and may be used as glass mat applications sold by Borden chemical company, Columbus, Ohio and sold by Neste's Resins Corporation, Eugene, oreg. These resins are generally modified with reactive methylol groups that form methylene or ether chains upon curing. Such methylol groups may include N, N ' -dimethylol, dihydroxymethylolethylene, N ' -bis (methoxymethyl), N ' -dimethylolpropylene, 5-dimethyl-N, N ' -dimethylolethylene, N ' -dimethylolethylene and the like.

In one embodiment, the condensation reaction is allowed to proceed to an extent such that the urea-formaldehyde resin has a number average molecular weight (M) greater than about 100 grams/mole_n) And often greater than about 300 grams/mole. Good results have been obtained in separations using urea formaldehyde base resins having molecular weights in the range of from about 400 to about 4000 g/mol and also in the range of from about 400 to about 1200 g/mol. M of one Polymer sample having a weight distribution, as known in the art_nThe values are defined as follows:

wherein N is_iIs the number of polymer species having i repeating units and M_iIs the molecular weight of the polymer species having repeating units i. The number average molecular weight is typically determined using Gel Permeation Chromatography (GPC), using solvents, standards and procedures well known to those skilled in the art.

A cyclic urea-formaldehyde resin may be used and prepared, for example, according to the procedure described in US patent No. 6,114,491.

Another aspect of the present invention relates to the following findings: cyclic urea prepolymers formed by reacting urea, formaldehyde and ammonia or a primary amine are useful as modifiers in phenolic resins and melamine-formaldehyde resins. The present invention may be used to further modify a resin system by reacting into a base resin system, blending with a finished base resin system, or blending into an adhesive article.

The resin may then be used in the compositions or adhesive compositions described herein, including various liquid forms, including solutions, miscible liquids or dispersions, and the like, and combinations of such liquid forms, depending on the optional ingredients blended into the adhesive composition. When a solution or any of its variants is used herein, it is intended to include any relatively stable liquid phase.

As disclosed, the cyclic urea prepolymer can be prepared by any suitable method. For example, urea, formaldehyde, and ammonia or a primary amine are mixed and heated to a desired temperature for a fixed period of time to form a cyclic urea prepolymer. Preferably, the molar ratio of reactants for the cyclic urea prepolymer is as follows:

formaldehyde: about 0.1 to 3.0

Ammonia or primary amine: about 0.1 to 1.0

Any combination of the above molar ratios is contemplated; preferably, however, the molar ratio of urea to formaldehyde to ammonia or primary amine is about 2.0: 1.0 to 1.0: 4.0: 1.0 and more preferably about 2.0: 4.0: 1.0 depending on the application. It is contemplated that "ammonia or a primary amine" also includes the use of both ammonia and one primary amine or more than one primary amine.

The urea, formaldehyde, and ammonia reactants are used in a molar ratio of formaldehyde to ammonia that can be from about 0.1 to 1.0 to about 0.1 to 3.0 to about 0.1 to 1.0. The reactants were fed to a reaction vessel while maintaining the temperature below 70 ℃ (160 ° F), often 60 ℃ (140 ° F). The order of addition is not critical, but it is important that care be taken during the addition of ammonia to the formaldehyde (or formaldehyde to ammonia) due to the exothermic reaction. Indeed, due to the strong exotherm, it may be preferred to charge formaldehyde and urea first, followed by ammonia. This sequence of addition allows us to take advantage of the endotherm of adding urea to water to increase the rate of ammonia addition. A base may be required to maintain an alkaline condition throughout the cooking process.

Once all the reactants are in the reaction vessel, the resulting solution is heated at an alkaline pH to between about 60 ℃ and 105 ℃ (about 140 to about 220 ° F), often about 85 ℃ to 95 ℃ (about 185 ° F to 205 ° F) for 30 minutes to 3 hours, depending on the molar ratio and temperature, or until the reaction is complete. Once the reaction was complete, the solution was cooled to room temperature for storage. The resulting solution was stable for several months under ambient conditions. The pH is between 5 and 11.

The yield is typically about 100%. The cyclic urea resins often contain at least 20% of triazinone and substituted triazinone compounds. The ratio of cyclic ureas to di-and tri-substituted ureas and mono-substituted ureas varies with the molar ratio of these reactants. For example, a cyclic urea resin having a U: F: A molar ratio of 1.0: 2.0: 0.5 results from C¹³-a solution characterized by NMR and comprising about 42.1% cyclic urea, 28.5% di/tri-substituted urea, 24.5% mono-substituted urea and 4.9% free urea. A cyclic urea resin having a molar ratio of U: F: A of 1.0: 1.2: 0.5 results from C¹³-a solution characterized by NMR comprising about 25.7% cyclic urea, 7.2% di/tri-substituted urea, 31.9% mono-substituted urea and 35.2% free urea.

The phenolic resole resin may be prepared by any known means. For example, the phenolic resin may be prepared by reacting a molar excess of formaldehyde with phenol under basic reaction conditions. Formaldehyde is used in an amount between about 0.5 and 4.5 per mole of phenol, with the preferred range depending on the application. The% free formaldehyde is typically between 0.1% and 15%. And the% free phenol is typically between 0.1% and 20%. The preferred range depends on the application.

Basic reaction conditions are established by adding a basic catalyst to a solution of phenol and formaldehyde reactants. During the initial reaction of the phenol and formaldehyde, only the amount of basic catalyst needed to produce a resin needs to be added to the reaction mixture. Suitable amounts of catalyst are known to those skilled in the art. Typically about 0.005mol of basic catalyst per mole of phenol is used, with an amount between about 0.01 and 1 mol per mole depending on the application. The catalyst, which may be added initially to the reactants or catalyst, may be added incrementally in two or more additions or continuously over a defined period of time.

Basic catalysts commonly used for the preparation of phenolic resins may also be used according to the present invention. Typical basic catalysts include alkali and alkaline earth metal hydroxides, such as lime, lithium hydroxide, sodium hydroxide, and potassium hydroxide; alkali metal carbonates such as sodium carbonate and potassium carbonate; and amines. Sodium hydroxide is most commonly used due to cost and availability considerations.

Depending on the resin requirements, the cyclic prepolymer may be reacted into the phenolic resin or added as a post blend. The preferred method depends on the application. For example, a cyclic urea prepolymer is blended with a phenolic resin prepared to produce a binder suitable for insulation.

It may be preferred to react the cyclic urea prepolymer with formaldehyde to tie it throughout the polymer structure before attempting to react the material with phenol. Typically, the reaction is carried out by adding the cyclic urea and formaldehyde (50%) together in a ratio of about 4 to 1, preferably about 2: 1, to a suitable vessel, adjusting the pH to 8.5 to 10.0, preferably about 9.0 to 9.5 and heating to 80 ℃ to 100 ℃, preferably about 90 ℃ to 95 ℃. The mixture was allowed to react under these conditions for about two hours. The product is then added to the phenolic resin prior to which half of the added formaldehyde is removed from the resin formaldehyde charge. The resin was standardized and used for its application.

The reaction with phenol is achieved by: the pre-methylolated cyclic urea prepolymer is added to all phenols commonly used to make the base resin and the pH is adjusted to about 9.5 to 11.5, preferably about 10.5, by the addition of NaOH (50%). The mixture is then heated to about 80 ℃ to 100 ℃, preferably about 90-95 ℃ for about one hour or more, depending on the pH. The product of this step is a phenol-cyclic urea prepolymer reaction product that can be used to make the base resin.

The concentration of the feedstock is not critical. Water may be added or removed by distillation to adjust the% non-volatiles to the desired level. The resin and cyclic urea prepolymer are combined to obtain from 1 to 95 wt% cyclic urea prepolymer solids, preferably from 10 to 70 wt%. The preferred range depends on the application.

Furthermore, the cyclic urea-formaldehyde resin can be prepared by a process such as described in US patent No. 5,674,971. The cyclic urea resins are prepared by reacting urea with formaldehyde in at least a two-step and optionally a three-step process. In this first step, which is carried out under basic reaction conditions, urea and formaldehyde are reacted in the presence of ammonia in a molar ratio F/U of between about 1.2: 1 and 1.8: 1. The ammonia is provided in an amount sufficient to produce an ammonia/urea molar ratio of between about 0.05: 1 and 1.2: 1. The mixture is reacted to form a cyclotriazinone/triazine or cyclic urea resin.

Water-soluble triazinone compounds can also be prepared by reacting urea, formaldehyde and a primary amine as described in US patent nos. 2,641,584 and 4,778,510. These patents also describe suitable primary amines, such as include, but are not limited to, alkylamines, such as methylamine, ethylamine, and propylamine, lower hydroxylamines, such as ethanolamine, cycloalkylmonoamines, such as cyclopentylamine, ethylenediamine, hexamethylenediamine, and linear polyamines. The primary amine may be substituted or unsubstituted.

In the case of a cyclic urea-formaldehyde or a urea-formaldehyde resin, it is recognized by those skilled in the art that urea and formaldehyde are commercially available in a variety of forms. Any form that is sufficiently reactive and does not introduce extraneous moieties deleterious to the desired reaction and reaction product can be used to prepare the urea-formaldehyde resins useful in the present invention. For example, commonly used forms of formaldehyde include paraformaldehyde (solid, polymerized formaldehyde) and formalin solutions (aqueous solutions of formaldehyde, sometimes containing methanol, with a formaldehyde concentration of 37 percent, 44 percent, or 50 percent). Formaldehyde can also be obtained as a gas. Any of these forms is suitable for use in the preparation of urea-formaldehyde resins. Typically, formalin solutions are used as the formaldehyde source. To prepare the resins of the invention, formaldehyde may be substituted, in whole or in part, with any of the aldehydes described above (e.g., glyoxal).

Urea formaldehyde Resins may be used, such as the types sold by Georgia Pacific Resins, inc., border Chemical co., and Neste Resins Corporation. These resins are prepared as either low molecular weight condensates or as adducts, which as described above contain reactive methylol groups that can undergo condensation reactions to form resin polymers, often within the number average molecular weight ranges previously described. These resins generally include small amounts of unreacted (i.e., free) urea and formaldehyde, as well as cyclic ureas, mono-methylolated ureas, and di-and tri-methylolated ureas. The amount of these species reacted may vary depending on the preparation conditions (e.g., aldehyde: urea molar ratio used). The balance of these resins are generally water, ammonia, and formaldehyde. Various additives known in the art, including stabilizers, cure accelerators, fillers, expansion agents, and the like, may also be added to the resin.

The above-described amine-aldehyde resins are highly selective for binding undesirable solid materials (e.g., sand or clay) and/or ionic species such as metal cations to be separated in the separation/purification process of the present invention. Without being limited by theory, the amine-aldehyde resins of the present invention are generally cationic (i.e., carry a generally more positive charge than a negative charge) in one embodiment so as to attract most of the clay surfaces, which are generally anionic (i.e., carry a generally more negative charge than a positive charge). The difference in charge characteristics between the resin and the clay results in attractive interaction at multiple sites and even potential electron sharing to form covalent bonds. The interaction of positive and negative charges that causes the clay particles to become attracted to the resin is likely to be explained by several theories, such as host-guest theory (including multidentate ligands), hard-soft acid-base theory, dipole-dipole interaction, highest occupied molecular orbital lowest unoccupied molecular orbital (HOMO-LUMO) interaction, hydrogen bonding, gibbs free energy of bonding, and the like.

Silica, silicates and/or polysiloxanes may be used in combination with the amine-aldehyde resins of the present invention (e.g., added as a blend component) to potentially improve their affinity for various materials, particularly siliceous materials, including sand and clays, whether such materials are desirable or undesirable in any particular application. Other agents that may be used to enhance the performance of the resins of the invention in the separation process of the invention include polysaccharides, polyvinyl alcohol, polyacrylamide, as well as known flocculants (e.g., alginates). These agents may also be used with modified urea-formaldehyde resins, wherein at least a portion of the urea is replaced with ammonia or an amine (e.g., primary alkyl amine, alkanolamine, polyamine, etc.) as described above. In addition, these reagents may be used with resins modified with anionic functional groups (e.g., sulfonate salts) or resins stabilized by esterification with an alcohol (e.g., methanol), as described below.

Silica in the form of an aqueous silica sol is available, for example, from Akzo Nobel under the registered trademark "Bindzil" or from DuPont under the registered trademark "Ludox". Other grades of sols are available having different particle sizes of colloidal silica and including different stabilizers. The sol may be stabilized by a base, for example sodium, potassium or lithium hydroxide or quaternary ammonium hydroxide, or by a water-soluble organic amine, such as an alkanolamine.

Silicates such as alkali and alkaline earth metal silicates (e.g., lithium, sodium-lithium, potassium, magnesium and calcium silicates) along with ammonium silicate can also be used in the preparation of the resins. Furthermore, stabilized colloidal silica-silicate blends or mixtures, as described in US patent No. 4,902,442, are applicable.

In the separation process of the present invention, the amine-aldehyde resin may be used in the form of a solution or dispersion having a resin solids content generally of from about 0.1% to about 90% by weight. For example, good performance is obtained when the resin is prepared in a solution having a solids content of from about 30% to about 90% and typically from about 45% to about 70%. In addition, "undiluted" forms of the resin with little or no added solvent or dispersing agent (e.g., water) can also be used. When an amine aldehyde resin is used in a substantially "undiluted" form with little or no volatile components, the resin may be added neat (e.g., as a viscous liquid, a sol, or a solid form such as a powder) to the froth flotation slurry or liquid dispersion to be purified, thus forming an aqueous resin solution or dispersion in situ. The amine-aldehyde resins in undiluted form can be obtained from solutions or dispersions of these resins using conventional drying techniques (e.g., spray drying). In some cases, a resin solids content of greater than about 90% by weight may therefore be used. Forms of the amine-aldehyde resin at such high solids levels include viscous liquids, sols, melts, or solid forms, including pellets, blocks, tablets, or powders (e.g., spray-dried materials).

In any event, the amine and aldehyde components, typically at least about 90% by weight and often at least about 95% by weight, used to form the resin are reacted to reduce the amount of free (unreacted) amine and formaldehyde. This practice more efficiently utilizes the amine and aldehyde components in producing the resin polymer while minimizing any deleterious effects (e.g., evaporation into the environment) associated with these components in their free form. Generally, the amine aldehyde resins used in the separation process of the present invention generally comprise from about 40% to about 100% resin solids or non-volatile materials and often 55% to 75% non-volatile materials. However, such resins may be diluted to a lower solids content (e.g., less than about 30% by weight) for storage, for example, using a saline solution in conjunction with a thickener such as poly (acrylic acid). The nonvolatile content is measured by weight loss after heating a small amount (e.g., 1-5 grams) of the composition at about 105C for about 3 hours. The aqueous solution or dispersion of the resin of the present invention is generally a clear liquid or a liquid having a white or yellow appearance. They typically have a brookfield viscosity of from about 75 to about 500cps and a pH of from about 6.5 to about 9.5. The free formaldehyde content as well as the free urea content of the urea-formaldehyde resin is typically below 5% each, usually below 3% each and often below 1% each. Due to health issues associated with exposure to formaldehyde emissions, it is generally a low formaldehyde content that is achieved. If desired, conventional "formaldehyde scavengers" known to react with free formaldehyde may be added to reduce the formaldehyde level in the solution. Low amounts of free urea are also desirable, but for different reasons. Without being limited by theory, free urea is not believed to have the requisite molecular weight in the following process: (1) in froth flotation separation, to cause the gangue or desired material (e.g., clay) to "mask" their interaction with the rising air bubbles, (2) to agglomerate a sufficiently large number of solid contaminant particles into floes in the purification of liquid dispersions, or (3) to remove ionic species from aqueous solutions to bind these species to molecules of sufficient size for retention by filtration. In particular, it has been found that resinous polymers having a number average molecular weight greater than about 100 grams/mole and often greater than about 300 grams/mole exhibit the agglomerates necessary to facilitate effective separation.

Froth flotation process

The resins of the present invention provide good results at economical addition levels when used as depressants in froth flotation separations due to their high selectivity. For example, the resins can be added in an amount of from about 100 to about 1000 grams, and typically from about 400 to about 600 grams, based on the resin solution or dispersion weight per metric ton of material (e.g., clay-containing ore) to be purified by froth flotation. In general, the optimum amount added for particle separation can be readily determined by one skilled in the art and depends on a number of factors, including the type and amount of impurities.

Amine-aldehyde resins can be used in the froth flotation of a variety of valuable materials (e.g., minerals or metals such as phosphates, potash, lime, sulfates, gypsum, iron, platinum, gold, palladium, titanium, molybdenum, copper, uranium, chromium, tungsten, manganese, magnesium, lead, zinc, clay, coal, silver, graphite, nickel, bauxite, borax, borates, or high molecular weight hydrocarbons such as asphalt). The feedstock to be purified and recovered often comprises sand or clay for which the resin depressant described herein is particularly selective.

Although clay is often considered an impurity in the enrichment of conventional metal or mineral ores, it may also be present in relatively large amounts as a major component to be recovered. Certain clays, such as kaolin, are valuable materials in a variety of applications, such as mineral fillers for the production of paper and rubber. Thus, one froth flotation process in which the resins of the invention may be used involves separating clay from clay-containing ores. The impurities in these ores are generally metals and their oxides, such as iron oxide and titanium dioxide, which are preferably floated by froth flotation. Other impurities of clay-containing ores include coal. Impurities originally present in most georgia kaolins, which are preferably buoyant in the purification process of the present invention, include iron-bearing titanium dioxide and various minerals such as mica, ilmenite, or tourmaline, which are also generally iron-containing.

Thus, the clay selectively bound to the amine-aldehyde resin of the present invention is separately recoverable from metals, metal oxides, and coal. In the purification of clay, it is often advantageous to control flotation using an anion collector such as oleic acid, a flocculant such as polyacrylamide, a clay dispersant such as a fatty acid or a rosin acid, and/or oils in combination with the resin of the present invention as a depressant. A method, particularly for use in the purification of clay-containing ores, as described in more detail below, involves modifying a resin with an anionic functional group.

Other representative froth flotation processes of the present invention involve the above-described enrichment of coal along with other valuable metals and minerals, where the removal of siliceous gangue materials such as sand and/or clay and other impurities is an important factor in achieving favorable process economics. For example, metal and mineral ores, generally in addition to the valuable metal or mineral, include a mixture of various mineral impurities that are desired to be recovered in a froth concentrate. These impurities may include halite (NaCl), clay, and carbonate minerals that are insoluble in water, such as aluminum silicate, calcite, dolomite, and anhydrite. Other ore impurities include iron oxides, titanium oxides, iron-bearing titanium dioxide, mica, ilmenite, tourmaline, aluminum silicate, calcite, dolomite, anhydrite, ferrimagnesium minerals, feldspar, and rock debris or various other solid impurities such as igneous rocks and soil. In the case of coal enrichment, non-combustible solid materials such as calcium magnesium carbonate are considered impurities.

The resins of the present invention are also advantageously used to separate bitumen from sand and/or clay co-extracted from natural oil sands deposits. The bitumen/sand mixture removed from oil or tar sands deposits, often within hundreds of feet of the earth's surface, is generally first mixed with warm or hot water to produce an aqueous oil sands slurry having a reduced viscosity that facilitates its transport (e.g., via pipelines) to processing equipment. Steam and/or alkaline solution may also be injected to condition the slurry for flotation along with any number of other purification steps as described below. Aeration of a bitumen-containing slurry comprising sand or clay results in selective flotation of the bitumen, which allows it to be recovered as a purified product. The aeration may be accomplished by merely agitating the slurry to release air bubbles and/or introducing a source of air into the bottom of the separation chamber. The optimum amount of air required to float the desired bitumen without entraining excessive amounts of solid contaminants is readily determined by one skilled in the art.

Thus, the use of the resin depressant of the present invention advantageously promotes retention of sand and/or clay impurities in the aqueous portion that is then removed from the bottom of the froth flotation vessel. The bottoms fraction is enriched (i.e., has a higher concentration) with sand and/or clay impurities relative to the initial bitumen slurry. The entire purification process of bitumen may rely on two or more flotation separation stages. For example, the intermediate portion of a primary flotation separation vessel may contain significant amounts of bitumen that may ultimately be recovered in a secondary flotation of the "intermediate" portion.

The amine-aldehyde resins can also be useful for froth flotation of valuable materials as described herein to remove metal contaminants and heavy metals, including in particular mercury, cadmium, lead and arsenic, and also compounds containing these heavy metals. Treatment of an ore slurry with resin may alternatively be accomplished with any other type of separation discussed below (e.g., filtration, cyclonic separation, flotation without the use of air bubbles, etc.) in addition to froth flotation, along with dissolved air flotation discussed below with respect to the removal of mercury from synthetic gypsum. In the context of the removal of heavy metal contaminants, the purification of coal represents one particular application that increases environmental significance. Coal typically contains, for example, 0.03-0.3 parts per million by weight (ppm) total mercury on a volatile-free (or non-volatile basis as described herein). The ever stricter regulatory standards for airborne mercury release have resulted in the need for highly efficient mercury reduction systems (e.g., activated carbon sorbent materials) released from the flue gas of coal-fired power plants. The pressure of these systems can therefore be reduced by enriching the coal ore used in power generation in order to reduce the total mercury content present therein. Currently, about 100 million tons of coal mine rock are treated using conventional froth flotation.

Mercury can also be designed to reduce sulfur emissions (primarily SO) from coal-fired power plants₂) Is accumulated in the system of (1). For example, sulfur removal and recovery is often accomplished by a flue gas desulfurization process that involves scrubbing (or contacting) the exhaust gas from coal combustion with an aqueous base solution that rapidly dissolves, reacts with, and neutralizes the sulfur oxide contaminants. Often, an economically attractive method of sulfur recovery involves the use of aqueous calcium hydroxide (or lime) as the scrubbing medium, which reacts with sulfur oxides to form calcium sulfate, also known as synthetic stoneAnd (6) making paste. The resulting slurry of precipitated synthetic gypsum can be filtered to reduce its moisture content and further processed in conventional gypsum operations, such as in the production of gypsum wallboard.

The presence of mercury in the coal can thus ultimately lead to mercury contamination in the synthetic gypsum produced by desulfurization of the flue gas. In particular, trace amounts of gaseous mercury in flue gases tend to accumulate in alkaline scrubbing solutions. In addition, the gaseous hydrogen chloride, also commonly present in flue gases, converts elemental mercury to HgCl₂The HgCl₂Can adhere to the precipitated, solid synthetic gypsum particles.

Treatment of the synthetic gypsum slurry with a depressant comprising the amine-aldehyde resin of the present invention in combination with froth flotation or other separation methods described herein allows for a reduction in mercury pollution levels. It is also possible to form a slurry of synthetic gypsum that has been dewatered (e.g., using filtration as described above), and then treat the slurry with a resin to effectively reduce the amount of mercury by froth flotation. Preferably, however, inefficiencies associated with dewatering and subsequent rehydration are avoided by treating and subjecting the slurry to flotation prior to filtering the synthetic gypsum. In any event, a representative enrichment process of the invention comprises treating a slurry of coal or synthetic gypsum-containing ore with a depressant containing an amine-aldehyde resin of the invention. In the case of synthetic gypsum, the material to be purified is preferably formed during the desulfurization of flue gases from coal-fired power plants as described above.

The treatment of the synthetic gypsum slurry may be combined with froth flotation during or after the treatment. Enrichment may alternatively involve any of the separation methods discussed herein (e.g., filtration, size or density fractionation, etc.). One particular separation process of interest in the removal of mercury from synthetic gypsum is known as Dissolved Air Flotation (DAF), which can be facilitated by the use of amine-aldehyde resins. The use of DAF to remove algae and arsenic from Water is described, for example, in Wert et al, Proceedings Water Quality Technology Conference (2003), p.902-918. Regardless of the nature of the separation, however, the recovery and/or purity of the purified synthetic gypsum in the separation process for mercury removal may be enhanced by using one or more chelating agents in combination with the resin as discussed below. Chelating agents that are particularly useful in separating mercury from synthetic gypsum will not only form a complex with mercury, but will also include a functionality that improves the ability of the complexed species to selectively report a desired stream, such as a foam concentrate (e.g., in a foam flotation where the purified synthetic gypsum product is selectively inhibited). These functionalities include those that are common in conventional collectors (which aid flotation) or those that aid solvation or compatibilization of the complexed mercury.

In a representative beneficiation process using froth flotation, the treatment of the coal or synthetic gypsum feedstock slurry with the amine aldehyde resin can occur prior to or during the froth flotation. As a result of froth flotation, the purified coal or purified synthetic gypsum can be selectively recovered in a froth concentrate or selectively precipitated into a stream of bottoms or residual oil depending on the particular operating conditions used. Also, mercury and mercury-containing compounds can be selectively floated or selectively suppressed. Froth flotation parameters that determine which constituents are suppressed or floated in a particular separation are well known to those skilled in the art. Typically, in froth flotation of synthetic gypsum, the purified gypsum is selectively inhibited while relatively small amounts of mercury or other contaminants are selectively floated. In contrast, froth flotation of coal is typically carried out with purified coal being selectively recovered in a froth concentrate and mercury and other impurities being recovered in a stream of bottoms or resid.

In any event, whether the mercury contaminants are selectively floated or inhibited, their separation from the valuable minerals may be enhanced by using one or more conventional chelating agents in combination with the amine-aldehyde resin. A chelating agent may be added to the ore slurry with the amine-aldehyde resin, or alternatively before or after the resin is used. Suitable chelating agents have the ability to effectively bind or form a metal ligand complex with mercury. The chelating agent can additionally enhance the enrichment of coal, in particular by removing iron contaminants as well as iron sulfides (pyrite). The reduction of both iron and sulfur content in the purified coal enhances its fuel value (by reducing non-combustibles) along with its acid gas release characteristics (by reducing sulfur).

Chelating agents include, for example, multifunctional carboxylates such as hydroxyethylenediaminetriacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and nitrilotriacetic acid (NTA), which are typically used in the form of their corresponding acetates (e.g., their sodium salts such as DTPA pentasodium or NTA trisodium). These chelating agents include, for example, thoseProducts of the family (Akzo-Nobel Functional Chemicals bv, Netherlands) such asH-40、 D-40、 D-40-L, andA-150-S. Salts of oxalic acid (oxalates) may also be used alone or in combination with these chelating agents. Amino acids are also useful as agents having a carboxylic acid group, which can chelate with iron and other metal contaminants. When used in conjunction with an amine-aldehyde resin, the amine groups of the amino acids can covalently react onto the resin backbone, thereby providing the resin with the desired chelating functionality. Suitable amino acids include arginine, cysteine, serine, alanine, and the like. Also, a variety of reagents (e.g., caprolactam and its derivatives) can be usedTacyclic amines) to form species having both amino and carboxylic acid functionalities, which similarly may add chelating functionality to the amine-aldehyde resin.

Other classes of chelating agents include resins having functional groups that carry sulfur atoms, such as thiosemicarbazides and derivatives thereof. The thiosemicarbazide may be incorporated into a resin, such as a styrene-divinylbenzene copolymer or an ion exchange resin, such as a weakly acidic Amberlite IRC-(Rohm and Haas Company, Philadelphia, PA USA). In the latter case, the resulting polymer includes one multidentate chelate ring containing O, N and S donor sites. One representative thiosemicarbazide-derived functional group is diacetyl-bis (N-methylthiosemicarbazone).

Other sulfur-containing additives may likewise improve the efficiency (e.g., product purity and/or recovery) of froth flotation for removing mercury from coal or synthetic gypsum and thus may be combined with amine-aldehyde resins and optionally further used in combination with one or more of the chelating agents described above. Species having one or more mercapto functional groups along with one or more acid functional groups are useful in this application, and these include, for example, sodium 2, 3 dimercaptopropane sulfonate (DMPS) and 2, 3-rac-dimercaptosuccinic acid (DMSA). Other sulfur-containing species such as alpha lipoic acid, cysteine, and glutathione may also be used to form mercury complexes, resulting in improved sequestration of mercury in the froth flotation bottoms product. The thioacid homologs of the carboxylic acid chelating agents discussed above, along with their corresponding thioester derivatives, are also suitable for this purpose. Iodine-containing derivatives of any of the chelating agents discussed above may also be effective in forming stable complexes with mercury and other metal impurities. For the purposes of this disclosure, the effectiveness associated with any of the above chelating agents, sulfur-containing compounds, or additives for any particular application in any given amount can be readily determined by one of skill in the art. The efficiency of a given sulfur-containing compound will depend not only on its affinity for mercury contaminants in the coal or synthetic gypsum, but also on its ease of separation from the purified product in its complexed and uncomplexed state.

Other additives that may be combined with the amine-aldehyde resin to potentially improve its performance in coal mine rock enrichment by froth flotation include known reagents, collectors, frothers, accelerators and other examples used in this application, such as described by Laskowski in C_OAL F_LOTATIONAnd F_INE C_OAL U_TILIZATIONElsevier (2001).

As a result of the enrichment, the total amount of final mercury present in the ore (e.g., including coal or synthetic gypsum) is less than the initial amount based on the volatile-free weight (i.e., the initial total mercury amount is reduced). In representative embodiments, the final total mercury amount is less than about 10 parts per billion (ppb), less than about 5ppb, or even less than 1 ppb. The final amount of total mercury may range, for example, from about 1 to about 100ppb, from about 1 to about 10ppb, or from about 5 to about 50 ppb. Any conventional method (e.g., Inductively Coupled Plasma (ICP) or Atomic Absorption Spectroscopy (AAS) analysis) can be used in the determination of the total mercury amount, which refers to the amount of mercury present in elemental form as well as in the form of mercury-containing compounds.

In the case of coal ores used in power plants, the removal of other impurities besides heavy metals can significantly improve the combustion value and/or the resulting combustion emissions of the purified coal recovered by froth flotation or other separation methods discussed herein. For example, the reduction of nitrogen and sulfur containing compounds is important in many cases to comply with nitric oxide and sulfur oxide release tolerances designed to reduce the prevalence of acid rain precursors in these environments. Froth flotation of impure coal ores is conventionally used in this way to upgrade the feedstock of coal-fired power plants. The removal of unwanted contaminants by froth flotation can be facilitated by treating an aqueous slurry of impure coal ore with the amine-aldehyde resin of the present invention before or during the flotation. In coal minesConventional froth flotation in the enrichment of stone is generally described, for example, inhttp://www.cq-inc.com/Coal-Primer.pdfIn (1). The purified coal recovered in the froth concentrate may have a reduced amount of impurities, such as nitrogen, sulfur, silicon, ash, or pyrite, relative to the impurity coal. The reduction of these impurities is determined on a volatile-free basis (e.g., on a volatile-free weight basis) as described herein.

The amount of nitrogen impurities refers to the total amount of nitrogen present in the nitrogen-containing compound in a coal sample expressed as a weight fraction of the element relative to the total volatile-free sample weight (or weight-%,% by weight-ppm, etc.). Other conventional measurements and analyses may also be used to compare the relative amounts of nitrogen in impure and purified coal samples, such as measurements of total organic nitrogen, total basic nitrogen, and the like. Sulfur and silicon impurities refer to the total amount of sulfur and silicon present either in elemental form or in the form of compounds containing these elements, also expressed as a weight fraction based on the weight of the volatiles. Silicon generally represents a significant portion of the non-combustible ash component of coal. In this way, enrichment for reducing measured ash can be similarly facilitated according to the methods described herein. Pyrite (or iron sulfide) is also commonly measured on a volatile-free basis to compare the amount of this impurity in purified coal relative to its amount in impure coal ores. The reduction in the pyrite content of the coal reduces the amount of sulfur impurities and also improves the combustion value (e.g., as measured in BTU/1 b).

Other benefits associated with the use of amine-aldehyde resins in froth flotation of coal may therefore include an increased BTU value per unit weight, or alternatively (or in combination) a reduced moisture content. In any case, the reduced amount of one or more of the above-described (e.g., two or more, or all) impurities in the purified coal recovered in the enrichment using froth flotation on impurity coal mine rock is preferably less than the corresponding reference amount of the purified reference coal recovered in the same froth flotation operation but without the use of amine aldehyde resins. Preferred moisture levels for coal purified according to any of the methods described herein are less than about 12% by weight, in the range from about 5% to about 12% by weight, and in the range from about 5% to about 10% by weight. Preferred combustion values are greater than about 12,000BTU/1b and range from about 12,000 to about 13,000BTU/1 b.

In general, in any froth flotation process according to the present invention, at least 70% of the valuable material (e.g. bitumen or kaolin) is recovered from the feed material (e.g. clay-containing ore), having a purity of at least 85% by weight. Also, when used as a depressant, conventionally known collectors can be used in combination with the resin of the present invention. These collectors include, for example, fatty acids (e.g., oleic acid, sodium oleate, hydrocarbon oils), amines (e.g., dodecylamine, octyldodecylamine, α -aminoarylphosphoric acid, and sodium sarcosinate), and xanthates (xanthates). Similarly, conventional depressants known in the art may also be combined with the resin depressants. Conventional depressants include guar gum and other hydrocolloid polysaccharides, sodium hexametaphosphate, and the like. Conventional frothers that aid in agglomeration (e.g., methyl isobutyl carbinol, pine oil, and polypropylene oxide) may also be used in conjunction with the resin depressant of the present invention in accordance with conventional flotation operations.

As will be appreciated by those skilled in the art, in froth flotation separation, when used as a depressant, the pH of the slurry to which the resin of the present invention is added will vary depending on the particular material to be treated. Typically the pH is in the range from neutral (pH7) to strongly basic (e.g., pH 12). It has been recognized that in certain flotation systems, high pH values (e.g., from about 8 to about 12.5) give the best results.

Typically, in froth flotation for solid materials, the crude ore to be subjected to enrichment is usually first ground to a "dissociation mesh" size. The solid material may be ground to produce, for example, one to eight inches average diameter particles prior to incorporation into the material as a brine solution to produce an aqueous slurry. After the material is crushed and slurried, the slurry may be agitated or stirred in a "washing" process that breaks down certain solids into very fine particles that remain in the brine as a slurry suspension. These fines may be washed of ore particles prior to froth flotation. Also, as is known in the art, any conventional size classification operation, some of which are discussed in detail below, may be used to further reduce/classify the feedstock particle size, remove clayed or ash-containing brine, and/or remove smaller solid particles from the slurry brine prior to froth flotation. These size classification operations include further pulverization/screening, cyclonic flow, and/or hydrogenation separation, any of which may be carried out with or without an amine aldehyde resin.

The ore beneficiation according to the present invention comprises treating the aqueous ore slurry with a depressant containing an amine-aldehyde resin as described herein. Treating mineral ore slurries with a depressant typically involves combining the depressant with the slurry (e.g., by adding the depressant to the slurry), usually in a manner such that the depressant is rapidly dispersed throughout. This treatment may occur before or during froth flotation, or before or during any of the other separation processes described herein (e.g., filtration, cyclonic separation, dissolved air flotation, etc.). In the case of treatment prior to froth flotation, the treatment may also include conditioning the ore prior to froth flotation in the presence of a depressant. It is beneficial to adjust to allow the depressant and ore slurry to thoroughly mix for a given period of time (typically from about 30 seconds to about 10 minutes) before subjecting the mixture to aeration or flotation. During the conditioning time, the depressant may combine with, for example, undesirable gangue materials, thereby improving the performance of subsequent froth flotation. Conditioning of a depressant/slurry mixture in the absence of aeration or froth flotation can occur in a separate conditioning vessel, such as a mixer or mechanical flotation cell, pipe, tank, etc., prior to transferring the mixture to a froth flotation cell. Alternatively, conditioning may take place in the same vessel used for froth flotation. The same or different conditions may be used for conditioning or flotation in terms of temperature, pH, agitation, etc. Typical conditions that may be used in one conditioning step include a temperature of from about 1 ℃ to about 95 ℃ and a pH of at least about 2.0, and often from about 3.0 to about 7.0. Also, the same reagents as conventionally used and/or discussed herein may be incorporated into the ore slurry in a conditioning step, in addition to the depressant. These agents include collectors, activators, flotation agents, pH modifiers, and the like.

In a froth flotation process, the slurry, typically having a solids content of from about 10% to about 50% by weight, is transferred to one or more froth flotation cells. Air is passed from the bottom of the cells and a relatively hydrophobic portion of the materials (having a selective affinity for the rising bubbles) floats up on the surface (i.e., the foam), where it is skimmed off and recovered. The bottom product, which is hydrophilic with respect to the froth concentrate, can also be recovered. This process may be accomplished by agitation. Commercially marketable products can be recovered in this manner in the separation section recovered in this manner, with steps often used after another conventional step including additional separation (e.g., by centrifugation), drying (e.g., in a gas fired kiln), size classification (e.g., screening), and purification (e.g., crystallization).

The froth flotation of the present invention may, although not always, involve "washing" of a "rougher unit" followed by one or more rougher aggregates. It is also possible to use two or more flotation steps to first recover a mass material containing more than one component, followed by selective flotation to separate the components. The amine-aldehyde resins of the present invention, when used as depressants, may advantageously be used in any of these steps to improve the selective recovery of the desired material by froth flotation.

When using multi-stage froth flotation, these resins may be added prior to multiple flotations using a single addition at a time or they may be added separately at each flotation stage.

Other methods of separation

Due to their affinity for solid contaminants in liquid suspensions or slurries, the amine-aldehyde resins of the present invention are suitable for use in a variety of separations and particularly in relation to the removal of siliceous materials, such as sand and/or clay, from aqueous liquid suspensions or slurries of these contaminants. The aqueous suspensions or slurries can thus be treated with the amine-aldehyde resins of the present invention, allowing at least a portion of the contaminants to be separated from a purified liquid in a contaminant-rich fraction. A "contaminant-enriched" fraction refers to a fraction of a liquid suspension or slurry that is enriched in solid contaminants (i.e., comprises a higher percentage of solid contaminants than originally present in the liquid suspension or slurry). In contrast, the purified liquid has a lower percentage of solid contaminants than originally present in the liquid suspension or slurry.

The separation methods described herein are applicable to "suspensions" of solid particles as well as "slurries". These terms are sometimes defined equivalently and are sometimes distinguished based on the need for at least some agitation or energy input to maintain homogeneity in a "slurry" context. Since the method of the invention described herein is broadly applicable to the separation of solid particles from an aqueous medium, the terms "suspension" and "slurry" are interchangeable in the description of the invention and in the appended claims (and vice versa).

The treating step may include adding a sufficient amount of amine-aldehyde resin to electronically interact with the coagulum and either coagulate or flocculate the solid contaminants into larger aggregates. The amount necessary can be readily determined depending on several variables, such as the type and concentration of the contaminant, as will be readily understood by those skilled in the art. In other embodiments, the treatment may include continuously contacting the solid suspension with a fixed bed of resin (in solid form).

During or after treatment of a liquid suspension with amine-aldehyde resins, the coagulated or flocculated solid contaminants (which may now be in the form of larger aggregated particles or flocs, for example) are removed. Removal can be accomplished by flotation (with or without the use of rising air bubbles as described previously with respect to froth flotation) or sedimentation. The optimal method for removal depends on the relative density of the floe and other factors. Increasing the amount of resin used to treat the suspension may in some cases increase the tendency of the flocs to float rather than settle. Filtration or straining may also be an effective means of removing agglomerated solid particle floes, whether they reside on a surface layer or in a sediment.

Examples of liquid suspensions that may be purified in accordance with the present invention include drilling fluids for oil and gas wells, which accumulate solid particles of rock (or drill cuttings) during their normal use. These drilling fluids (often referred to as "drilling mud") are important in the drilling process for several reasons, including the transfer of the drill cuttings from the drilling zone to the surface where their removal allows the drilling mud to be recycled. The addition of the amine-aldehyde resins of the present invention to oil well drilling fluids, and particularly water-based (i.e., aqueous) drilling fluids, effectively coagulates or flocculates the particulate contaminants into larger pieces (or flocs), thereby facilitating their separation by settling or flotation. The resins of the present invention may also be used in combination with known flocculants for this application such as polyacrylamides or hydrocolloid polysaccharides. Often, in the case of suspensions of water-based oil or gas well drilling fluids, the separation of these solid contaminants is sufficient to provide a purified drilling fluid for reuse in drilling operations.

Other aqueous suspensions of practical interest include clay-containing aqueous suspensions or brines accompanying the ore purification process, including those described above. The production of purified calcium phosphate, for example from mineral calcium phosphate rocks, generally relies on multiple separations of solid particles from an aqueous medium, whereby such separations can be improved using the resins of the present invention. In the overall process, calcium phosphate is mined from deposits that are on average about 25 feet deep below the horizon. The phosphate rock is initially recovered in a matrix containing sand and clay impurities. The matrix is first mixed with water to form a slurry that is typically screened after mechanical agitation to retain phosphate gravel and allow fine clay particles to pass as a clay slurry effluent with a large amount of water.

These clay-containing effluents generally have high flow rates and typically carry less than 10% by weight solids and more often contain only from about 1% to about 5% by weight solids. The dehydration of such waste clays (e.g., by settling or filtration), which allows the water to be recycled, presents a significant challenge associated with recovery. However, the time required for dehydrating the clay can be reduced by treating the clay slurry effluent obtained in the production of phosphate with the amine-aldehyde resin of the present invention. The reduction of clay settling time allows for efficient reuse of this purified water obtained from clay dehydration in the production of phosphate. In an embodiment of the purification process, wherein the liquid suspension is a clay-containing effluent slurry at a phosphate production plant, the purified liquid comprises less than about 1% solids by weight after settling or dewatering time of less than about 1 month.

In addition to screening the retained phosphate gravel and the clay slurry effluent described above, finer phosphate particles are obtained in the initial treatment of the harvested phosphate matrix. The sand and phosphate in the stream are separated by froth flotation, which separation can be improved as described before using the amine-aldehyde resin of the invention as a depressant for sand.

Another particular application of the resin in the slurry dewatering zone is in the filtration of coal from an aqueous slurry. The dewatering of the coal is commercially important because the BTU value, and therefore the quality of the coal, decreases with increasing water content. Thus, in one embodiment of the invention, amine-aldehyde resins are used to treat an aqueous coal-containing suspension or slurry prior to dewatering the coal by filtration.

As used herein, "enrichment" broadly refers to any process used to purify and/or upgrade a valuable material described herein. In the case of coal mine stone purification, various enrichment operations are routinely used in an effort to improve the quality of coal that is burned, for example, in a power generation plant. As previously discussed, for example, such quality improvement processes address environmental concerns, which has resulted in lower tolerances for metal contaminants (such as mercury and arsenic) along with nitrogen and sulfur-containing compounds that produce acid rain. As previously discussed, froth flotation provides a method of purifying a coal mine ore by treating an aqueous slurry of the ore with the amine-aldehyde resin of the present invention. The treatment may alternatively occur prior to or during conventional coal size or density classification to facilitate reduction in the amount of one or more of mercury, nitrogen, sulfur, silicon, ash, and pyrite impurities in the purified coal, wherein the impurities are measured on a volatile-free weight basis as previously described. The amine-aldehyde resin may also be used in conjunction with size or density classification operations to reduce moisture and/or increase the combustion value (e.g., as measured in BTU/1 b) of the purified coal. Preferably, the reduction in the amount of one or more of the above-described (e.g., two or more, or all) impurities in the purified coal recovered in the size or density fractionation operation above is preferably less than the corresponding reference amount for a purified reference coal recovered in the same size or density fractionation operation but without the use of an amine-aldehyde resin.

Overall, the above noted reduction of one impurity in the purified coal results in a corresponding reduction in the amount of the corresponding other undesirable impurity or impurities. For example, the reduction of pyrite generally results in the reduction of mercury and other inorganic materials such as siliceous ash. In one embodiment, the use of one or more size or density fractionation operations in combination with the amine-aldehyde resin produces the reduction in the amount of all impurities noted above.

Suitable conventional size or density classification operations include cyclonic separation, dense media (dense or dense media) separation, filtration, and screening, each of which may be used in conjunction (e.g., in series or parallel) with each other or with froth flotation. Generally, these operations are performed prior to froth flotation to provide, in combination with froth flotation, an upgraded or purified coal that meets the different specifications (e.g., nitrogen and sulfur levels) required for combustion in a power plant that generates electricity. For example, only water or staged cyclonic operation processes a feed stream of raw coal ore slurry that is fed tangentially under pressure into a cyclone. Centrifugal force moves the heavier metals to the walls of the cyclone where it is then typically delivered to an underflow at the tip (or grit chamber). The lighter coal particles aligned toward the center of the cyclone move through a duct (or vortex finder) into the upstream. The target density at which light and heavy particles are separated can be adjusted by varying the pressure, the length of the vortex finder, and/or the diameter of the blade tip. Such water-only or clarifying cyclones typically treat materials in the size range of 0.5-1mm and may include two or more separation stages to improve separation efficiency.

Dense media separation uses a dense liquid medium (e.g., pyrite at a particular pyrite/water ratio) to float particles (e.g., coal) having a density lower than the media density and settle particles (e.g., sand or rock) having a density higher than the media density. Dense media separation can be used in a simple deep or shallow "bath" configuration or can be included as part of a cyclonic separation operation to enhance gravitational separation forces and centrifugal forces. Often, one or more stages of clarifying cyclone separation operations are followed by one or more stages of heavy media cyclone separation and one or more screening steps to produce a suitably sized and purified (e.g., a preconditioned or pretreated) coal feed for subsequent froth flotation.

Another important application of the amine-aldehyde resins of the invention is in the field of sewage treatment, which refers to carrying out different processes for removing pollutants from industrial and municipal wastewater. Such a method thus purifies the wastewater to provide purified water suitable for disposal into the environment (e.g., rivers, brooks, and oceans) and a sludge. Sewage refers to any type of aqueous waste that is typically collected in a sewer system and transported to a treatment plant. Sewage thus includes waste from toilets (sometimes referred to as "dirty waste"), basins, bathtubs, showers, and kitchens (sometimes referred to as "residual water"). Sewage also includes industrial and commercial waste water (sometimes referred to as "industrial waste water") as well as runoff stormwater from hard surface areas such as roofs and streets.

Conventional treatment of wastewater involves primary, and secondary treatment steps. Primary treatment refers to the filtration or screening of large solids, such as wood, paper pieces, rags, etc., and also coarse sand and gravel, which often damage the pump. The majority of the remaining solids are then separated by settling in large tanks using a subsequent primary treatment, wherein a solids-rich sludge is recovered from the bottom of these tanks and further processed. A purified water is then recovered and typically subjected to secondary treatment by biological treatment.

Thus, in one embodiment of the invention, the settling or deposition of the sludge water may comprise treating the sludge with the amine aldehyde resin of the invention. The treatment may be used to enhance the settling operation (either batchwise or continuously), for example by reducing the residence time to achieve a given separation (e.g. based on the purity of the purified water and/or the percentage of solids recovered in the sludge). In addition, the improvement can be demonstrated in producing purified water of higher purity and/or a higher percentage recovery of solids in the sludge, for example, in a given settling time.

After the wastewater has been treated with the amine-aldehyde resins according to the invention and the purified water stream has been removed by sedimentation, it is also possible for the amine-aldehyde resins to be subsequently used or introduced into a secondary treatment process for further purification of the water. Secondary treatment typically relies on the breakdown of organic materials by naturally occurring microorganisms. In particular, the aerobic biological process substantially reduces the biological content of the purified water recovered from the primary treatment. These microorganisms (e.g., bacteria and protozoa) consume biodegradable soluble organic contaminants (e.g., sugars, fats, and other organic molecules) and incorporate more of the less soluble fraction into the floe, thereby further facilitating the removal of organic material.

Secondary treatment relies on "feeding" the aerobic microorganisms with oxygen and other nutrients that allow them to survive and consume organic contaminants. Advantageously, the amine-aldehyde resins comprising nitrogen of the present invention can serve as a "food" source for the microorganisms involved in the secondary treatment, as well as additional flocculants potentially for organic materials. Thus, in one embodiment of the invention, the wastewater purification process further comprises, after removing the purified water by sedimentation (in the first treatment step), further treating the purified water in the presence of microorganisms and an amine-aldehyde resin, and optionally reducing the Biochemical Oxygen Demand (BOD) of the purified water with an additional amount of amine-aldehyde resin. As is understood in the art, BOD is an important measure of water quality and represents the oxygen required by microorganisms to oxidize organic impurities in mg/l (or ppm by weight) over 5 days. The BOD of the purified water after treatment with the microorganisms and the amine-aldehyde resin is generally less than 10ppm, typically less than 5ppm and often less than 1 ppm.

The amine-aldehyde resins of the present invention can also be used for the purification of pulp and paper mill effluents. The stream of such aqueous waste typically includes solid contaminants in the form of cellulosic material (e.g., waste paper, bark, or other wood fractions, such as wood chips, wood strands, wood fibers, or wood particles, or plant fibers, such as wheat straw fibers, rice fibers, windy grass fibers, soybean straw fibers, bagasse fibers, or corn straw fibers, and mixtures of such contaminants). According to the process of the invention, a discharge stream comprising a cellulosic solid contaminant is treated with the amine-aldehyde resin of the invention, so that purified water can be removed by settling, flotation or filtration.

In separating bitumen from sand and/or clay impurities as described previously, different separation steps may be used before or after froth flotation of the bitumen-containing slurry. These steps may include screening, filtration, and settling, any of which may benefit from treating the oil sands slurry with the amine aldehyde resin of the present invention, followed by removal of a portion of sand and/or clay contaminants in a contaminant-rich fraction (e.g., a bottom fraction) or followed by removal of a purified bitumen fraction. As above with respect to the effluent of phosphate ore treatment water, which generally includes solid clay particles, the treatment step may include flocculating the contaminants to facilitate their removal (e.g., by filtration). The waste water from bitumen treatment plants also contains sand and/or clay impurities and therefore benefits in the treatment with the amine-aldehyde resins of the present invention, to dewater it and/or to remove at least a portion of these solid impurities in a contaminant-rich fraction. A particular process stream of interest generated during the extraction of bitumen is known as "mature fine non-distillate", which is an aqueous suspension of solid particles that can benefit from the dewatering process. Frequently, in the case of sand-and/or clay-containing suspensions from a bitumen production plant, the separation of solid contaminants is sufficient to allow recovery or removal of a purified water or water stream that can be recycled to the bitumen step.

The treatment of various intermediate streams and effluents in a bitumen production process with the resins of the present invention is not limited to only those processes that rely at least in part on froth flotation of aqueous bitumen-containing slurries. As will be readily understood by those skilled in the art, other techniques for bitumen purification (e.g., centrifugation by the "Syncrude process") will produce aqueous intermediate and byproduct streams from which it is desirable to remove solid contaminants.

The amine-aldehyde resins of the present invention can be used to remove suspended solid particles, such as sand and clay, in the purification of water (and in particular for the purpose of rendering it potable). In addition, the resins of the present invention have the additional ability to complex with metal cations (e.g., lead and mercury cations), thereby allowing these undesirable contaminants to be removed in conjunction with the solid particles. Thus, the resins of the present invention can be used to effectively treat impure water having both solid particulate contaminants and metal cation contaminants. Without being bound by theory, it is believed that electronegative moieties, such as carboxyl oxygen atoms on the urea formaldehyde resin polymer backbone, complex with undesirable cations to facilitate their removal. Generally, the complexation occurs at a pH of water that is greater than about 5 and typically ranges from about 7 to about 9.

Another possible mechanism for removing metal cations is based on their binding to negatively charged solid particles. Flocculation and removal of these particles therefore also (at least to some extent) leads to removal of the metal cations. Regardless of the mechanism, in one embodiment, both treatment and removal of these contaminants can be performed in accordance with the present invention to produce potable water.

The removal of metal cations may represent the predominant or even the only means of water purification by amine-aldehyde resins, for example when the water to be purified contains little or no solid particles. The solid form of the resin can be used in a continuous process to remove cations whereby impure water containing metal cations is continuously passed through a fixed bed of resin. Alternatively, a soluble form of the resin, generally having a lower molecular weight, may be added to the impure water to treat it. In this case, the complexed cations may be removed, for example, by ultrafiltration through a porous membrane (e.g., polysulfone) having a molecular weight cut-off less than the molecular weight of the resin. The water purification methods described herein may also be used in combination with known methods (e.g., reverse osmosis, ultraviolet irradiation, etc.).

To increase the effectiveness of the resins of the present invention in complexing with metal cations, it may be desirable to modify the amine-aldehyde resin with one or more anionic functional groups. These modifications are known in the art and involve reacting the resin to incorporate the desired functional groups (e.g., by sulfonation using sodium metabisulfite). Alternatively, the modification is achieved during the preparation of the resin (e.g. in a polycondensation reaction) by incorporating an anionic co-monomer (such as sodium acrylate) into the amine-aldehyde resin. Representative functionalities that may be used to modify the resin, including urea formaldehyde resins, include anionic functional groups bisulfite, acrylate, acetate, carbonate, azide, amide, and the like. Procedures for modifying resins with additional functionalities are also known to those of ordinary skill in the art. Incorporation of anionic functional groups into resins is also often used in purification involving slurries containing solid clay particles (e.g., by froth flotation, flocculation, etc.), including the purification of kaolin clay ores. Without being limited by theory, sulfonation of the resin or incorporation of other anionic functional groups may also increase hydrogen bonding between the resin and the enclosed aqueous phase in order to inhibit condensation of the resin or otherwise improve its stability.

Thus, as described above, in one embodiment the invention is a process for purifying water containing a metal cation by treating the water with the amine aldehyde resin described herein and it may be modified with an anionic group. Removal of at least a portion of the metal cations may be accomplished by retaining them on a fixed bed of resin or otherwise by filtering them. In the latter case, removal by filtration (e.g. membrane filtration) is made possible by the binding of the metal cations either directly to the amine-aldehyde resin or indirectly to the resin via solid particles to which the resin has an affinity. In the case of indirect bonding, as described previously, flocculation of the solid particles will also entail the accumulation of at least a portion of the metal cations, which may therefore be removed by flotation or sedimentation of these particles.

The amine-aldehyde resins of the present invention are therefore advantageously used to treat water to remove metal ions known to pose health risks when ingested, such as arsenic, lead, cadmium, copper, and mercury. These cations thus include As⁺⁵、Pb⁺²、Cd⁺²、Cu⁺²、Hg⁺²、Zn⁺²、Fe⁺²And mixtures thereof. In general, the degree of removal is achieved such that the purified water is substantially free of one or more of the above metal cations after treatment. By "substantially free" is meant that the concentration of one or more metal cations of interest is reduced to or below (e.g., by a regulatory agency such as the united states environmental protection agency) a concentration deemed safe. Thus, in various embodiments, the purified water will contain up to about 10ppb of As⁺⁵Up to about 15ppb of Pb⁺²Up to about 5ppb of Cd⁺²Up to about 1.3ppm Cu⁺²And/or up to about 2ppb of Hg⁺². That is, generally at least one, typically at least two, and often all of the above cations are at or below these threshold concentrations in the purified water.

In any of the applications described herein, it is possible to stabilize the amine-aldehyde resins of the present invention by reaction with an alcohol (i.e., esterification). Without being bound by theory, it is believed that the pendant alkyl alcohol functionality may inhibit further condensation of the amine-aldehyde resin (e.g., condensation of the urea-formaldehyde resin with itself). This may ultimately hinder or prevent precipitation of the resins during long term storage, such that these esterified resins may have increased molecular weight relative to their corresponding unesterified resins without concomitant loss of stability.

The esterification reaction thus comprises reacting the amine aldehyde resin adduct or polycondensate or even the resin prepared as described above with an alcohol. In one embodiment, a urea-formaldehyde resin is esterified with an alcohol having 1 to 8 carbon atoms. Representative alcohols for use in this esterification reaction include methanol (e.g., for methylation), ethanol, n-propanol, isopropanol, n-butanol, and isobutanol. In an exemplary preparation of the esterified resin, the amine aldehyde resin adduct or condensate reaction product is heated to a temperature of from about 70 ℃ to about 120 ℃ in the presence of an alcohol until the esterification reaction is complete. An acid such as sulfuric acid, phosphoric acid, formic acid, acetic acid, nitric acid, vanadium, ferric chloride, and other acids may be added before or during the reaction with the alcohol. Sulfuric acid or phosphoric acid is often used.

All references cited in this specification, including but not limited to all U.S. patents and patent applications, international and foreign, as well as all abstracts and articles (e.g., journal articles, periodicals, etc.), are hereby incorporated by reference in their entirety. The discussion of these references herein is intended merely to summarize the assertions made by their authors and no admission is made that any reference constitutes prior art. Applicants reserve the right to challenge the accuracy and pertinency of the cited references. In view of the above, it will be seen that the several advantages of the invention are achieved and other advantageous results attained.

As various changes could be made in the above methods and compositions without departing from the scope of the invention, it is intended that all matter contained in this application, including all theoretical mechanisms and/or modes of interaction described above, shall be interpreted as illustrative only and not limiting in any way the scope of the appended claims.

The following examples are presented as representative of the invention. These examples are not to be construed as limiting the scope of the invention as these and other equivalent embodiments are apparent from the disclosure and the appended claims.

Example 1

Different urea-formaldehyde resins are prepared as low molecular weight condensate resins, initially under basic conditions to form methylolated urea adducts and then under acidic conditions to form condensates. The condensation reaction is terminated by raising the pH of the condensation reaction mixture. Other operating conditions are as described above. These resins are indicated in table 1 below with respect to their molecular weight in grams/mole (mol.wt.) and the approximate normalized weight percentages of their free ureas, cyclic urea species (cyclic ureas), Mono-methylolated ureas (Mono), and combined Di/Tri-methylolated ureas (Di/Tri). In each case, the resins are in a solution having a resin solids content of 45-70%, a viscosity of 500cps or less, and a free formaldehyde content of less than 5% by weight.

TABLE 1 Urea Formaldehyde resin

Resin B is a very stable urea-formaldehyde resin with a high cyclic urea content. The resin is described in US patent nos. 6,114, 491.

Resin C' was formed by adding 2% by weight of diethylenetriamine and 2% by weight of dicyandiamide to a mixture of urea and formaldehyde during the preparation of the resin.

Resin D' was formed by adding 0.75% by weight of a cyclic phosphate ester to a mixture of urea and formaldehyde during the resin preparation. The resin is a low molecular weight formulation with high levels of free urea (essentially no free formaldehyde) and high levels of non-volatiles (about 70% solids).

a number average molecular weight determined using Gel Permeation Chromatography (GPC) using a PLgel of appropriate size^TMColumns (Polymer Laboratories, Inc., Amherst, MA, USA), a 0.5% glacial acetic acid/tetrahydrofuran mobile phase at 1500psi, and polystyrene, phenol, and bisphenol-A calibration standards.

Example 2

Samples of urea formaldehyde resins (UF) similar to those described in example 1 were tested for their ability to settle graphite and bentonite suspended in an aqueous medium. In four separate experiments, samples of 4.4 grams of particulate graphite (two experiments) and particulate bentonite (two experiments) were suspended in 220 grams of water in one bottle, and the bottles were shaken vigorously for two minutes in each case to suspend the solid particles. However, 22 grams of UF resin was added to one of the graphite containing bottles prior to shaking and also to one of the bentonite containing bottles. The four bottles were left to stand for 24 hours and observed to evaluate the effect of the added UF resin on solid-liquid separation by settling. Pictures were taken of these four bottles and are shown in figure 1.

As is clear from fig. 1, in the leftmost bottle to which the UF resin was added, graphite settled to the bottom of the bottle. Graphite is not visible at the air-water interface or on the surface of the bottle. The UF resin used in this case also settled with the graphite. In contrast, the second bottle from the left, to which no resin was added, had a significant amount of graphite adhered to its surface. Many graphites also remain at the air-water interface. Thus, the use of UF resins greatly facilitates the separation of graphite from water by settling.

Similarly, the bentonite settled to the bottom in the third bottle from the left to which the UF resin was added. The opacity of the liquid phase results from the use of a water-dispersible UF resin in this case. In contrast, the rightmost bottle with no resin added had a significant amount of solid bentonite adhered to its surface and remained at the air-water interface. Again, the use of UF resin significantly improved the separation of bentonite by settling.

Example 3

Similar Urea Formaldehyde (UF) resins as described in example 1 were tested for their ability to reduce dewatering time by filtering different solid contaminants (e.g., montmorillonite, bentonite, and graphite) suspended in an aqueous slurry. In each experiment, a 25 gram sample of solid contaminants was sampled with 100 grams of 0.01 molar KNO₃The slurry was homogenized. The pH of the slurry was measured. The slurry was then subjected to vacuum filtration using a standard 12.7cm diameter Buchner funnel device and 11.0cm diameter Whatman quality #1 filter paper. In addition to the first experiment using montmorillonite, the dewatering time in each case was the time required to recover 100ml of filtrate that passed through the filter paper. In the case of montmorillonite dewatering, the solids used are so fine that an excess of 5 minutes is required to remove 100ml of filtrate. Thus, the relative dewatering time is based on the amount of filtrate removed in 5 minutes.

For each solid contaminant tested, an identical experiment was followed by a comparative experiment except that (1) 0.5-1 gram of UF resin was added to the slurry and (2) the slurry was mixed for an additional minute after stirring to obtain a homogeneous slurry. The results are shown in table 2 below.

TABLE 2 dewatering time of aqueous slurries

(100 g of 0.01M KNO₃Middle 25g solid contaminant)

Amount of water removed over 5 minutes

Average of two experiments (139 sec/137 sec)

Average of two experiments (35 sec/38 sec)

Average of two experiments (9.3 sec/9.5 sec)

Average of two experiments (5.9 sec/6.2 sec)

The above results demonstrate the ability of UF resins to significantly reduce the dewatering time of large quantities of solid particles (even when used in small quantities).

Example 4

A urea-formaldehyde resin was prepared using the following reactants

A resin was prepared by charging UFC 85 (25% urea, 60% formaldehyde and 15% water), formalin and fresh water into a reactor and heating to 40 ℃ with stirring, then adding TEA and NH₄OH and hold for 5 minutes. The first urea charge was added with continuous cooling at 40 ℃. The reaction mixture was then heated to 95 ℃ over the course of 30 minutes and held at 95 ℃ for 15 minutes. The pH was monitored and adjusted by adding 10 to 25g of H₂SO₄It is adjusted to 5.0 to 5.3. A total of 135g was added over the course of one hour. The reaction mixture was cooled to 80 ℃. The second urea charge was added over the course of 5 minutes, heated to 85 ℃ and held at this temperature for a period of one hour, after which a second TEA charge was added and the temperature was cooled to 25 ℃. The pH was adjusted to pH 7.4-7.6 using 5.5g of 25% NaOH. The initial amount of formaldehyde is reduced to from 3.60 to 2.30 moles per mole of urea in the final product. The amount of ammonia was 0.40 moles per mole of urea. The level of fresh free formaldehyde at 0 ℃ was 0.12%. The level of free formaldehyde after 24 hours was 0.0%. The level of free formaldehyde was carried out using sodium sulfite ice.

Example 5

A urea-formaldehyde resin was prepared using the following reactants

A resin was prepared by charging UFC 85, formalin and fresh water into a reactor and heating to 45 ℃ with stirring. Then TEA and NH were added₄OH and hold for 5 minutes. The reaction was then cooled to 50 ℃ and the first urea charge was added. The reaction mixture was then heated to 95 ℃ over the course of 30 minutes and held at 95 ℃ for 15 minutes, the pH was checked and adjusted to 5.1 by adding sulfuric acid. The reaction mixture was cooled to 85 ℃ and a second urea charge was added over the course of 5 minutes. The pH was then adjusted to 7.0-7.4 by the addition of NaOH. A third urea charge was added and held for 20 minutes to remove free formaldehyde. The reaction medium was cooled to 40 ℃. A fourth urea addition was added and the resin was cooled to 25 ℃.

The ratio of ammonia to urea was 0.30. The formaldehyde to urea ratio was from 3.00 after the first urea addition, to 2.25 after the second urea addition, to 2.00 after the third urea addition, and to 1.90 after the fourth addition. The level of fresh free formaldehyde was 0.69%. The level of free formaldehyde at twenty-four hours was < 0.5 ppm. The level of free formaldehyde was determined using the sodium sulfite ice method.

Example 6

140g of FeSO₄Mixed with 25.2g of the urea-formaldehyde resin of example 3 of the invention and 2.3g of peat and compressed under pressure. Curing of the resin occurs at ambient temperature due to the presence of the acid salt. With this laboratory prepared mixture, the mixture changed from rigid to firm within 15 minutes without the addition of water as a binder for the ferrous sulfate agglomerates.

If desired, a small amount of water, about 7% based on the ferrous sulfate, may be added to extend the pot life of the mixture. If additional pot life is required, the polymerization formulation can be modified to adjust the coagulation cycle time of the polymer.

Example 7

Preparation of a urea-formaldehyde resin using reactants

A resin was prepared by charging 50% formalin, EDA (ethylenediamine) and urea to a reactor and heating the reaction mixture to 45 ℃ to dissolve the urea. Then NH is added₄OH, which causes the mixture to exotherm to a temperature of 83 ℃. The reaction mixture was then heated further to 95 ℃ and held at this temperature for 90 minutes. A cyclic polymer is formed in the initial phase of the chemical reaction. (the concentration of triazineone at this point in the synthesis process can be more than 50% of the total polymer mixture, depending on the molar ratio of the ingredients.) the pH of the mixture is monitored and maintained between 8.7 and 9.3 by the addition of 25% NaOH at spaced intervals as required. A total of 0.4 moles was added. The reaction mixture was then cooled to 85 ℃ and a second charge of UFC 85 (25% urea, 60% formaldehyde and 15% water) and urea was added to the reaction mixture. The temperature was then maintained at 85 ℃ for 10 minutes. The pH was adjusted in increments to from about 6.2 to 6.4 over the course of 25 minutes by adding a total of 0.2 moles of alum. The reaction mixture was cooled to 80 ℃ and after 15 minutes, further cooled to 75 ℃. After 7 minutes, the reaction mixture was cooled to 55 ℃, 26.9g of 25% NaOH was added, and then the mixture was further cooled to 35 ℃. A latent catalyst was added and the reaction mixture was cooled to 25 ℃. The pH was finally adjusted to 7.6 to 8.2 with 25% NaOH.

The level of fresh free formaldehyde of the resin thus produced was 0.59%. The level of free formaldehyde had decreased to 0.15% after 24 hours. The viscosity of the resin was 573 cp.

Example 8

About 1.2 moles of formaldehyde (50% solution), about 1.0 mole of urea, and about 0.5 moles of ammonia (as 28% ammonia hydroxide) were added to a glass reactor and heated to 95 ℃. The pH was maintained at 8.3 to 8.6 with 25% sodium hydroxide for 90 minutes. About 2.4 moles of formaldehyde and about 0.9 moles of urea are then added as UFC 85 and urea. The pH of the solution was adjusted to 4.9 to 5.1 with 50% aluminum sulfate and reacted to a Gardner-Holdt viscosity of "K". The polymer solution was then neutralized to ph7.4 with 25% sodium hydroxide and cooled to 25 ℃. The final brookfield viscosity was 200cps with a free formaldehyde level of about 0.5%.

Example 9

About 1.2 moles of formaldehyde (50% solution), about 0.0003 moles of triethanolamine, about 1.0 moles of urea, and about 0.5 moles of ammonia were added as 28% ammonia hydroxide to a glass reactor and heated to 95 ℃. The pH was maintained at 8.3 to 9.1 with 25% sodium hydroxide for 90 minutes. About 2.4 moles of formaldehyde and about 0.9 moles of urea are then added as UFC 85 and urea. The temperature was adjusted to 90 ℃ and the pH of the solution was adjusted to 5.1 to 5.3 with 50% aluminum sulfate and reacted to a Gardner-Holdt viscosity of "K". The polymer solution was then neutralized to pH 6.8 with 25% sodium hydroxide and cooled to 25 ℃. The final brookfield viscosity was 245cps with a free formaldehyde level of about 0.7%.

Example 10

Ammonia-modified aldehyde condensation polymers

An ammonia-modified aldehyde condensation polymer was prepared as described below. Wherein the pH adjustment is recorded below, using a sodium hydroxide solution (25% NaOH in water) and/or a sulfuric acid solution (7% H) if required₂SO₄In water). The following ingredients were then placed in a tank reactor in the following amounts:

2.5 parts of water

58.6 parts of formaldehyde solution (52% formaldehyde in water),

the reactor was equipped with a temperature controller, a stirrer and heating and cooling coils. As shown in example 2 below, urea formaldehyde concentrate is preferably used. These concentrates are commercially available and preferably from an economic point of view, less water needs to be added and removed. The pH is adjusted to about 4.7-4.9. About 8.8 parts ammonium hydroxide solution (28% NH) is then added in less than about 25 minutes₄OH in water). Heat is applied to achieve a temperature of about 75 ℃ and held at this temperature for about 5 minutes. The pH is adjusted to at least about 8.0. The reactor contents were then cooled to less than about 55 ℃. About 29 parts of urea pellets were added thereto while continuing to cool and maintain a temperature between about 20 ℃ and about 35 ℃. Pellets or pellets of urea may also be used. While mixing to dissolve the urea, the reactants were heated to about 40 ℃. The pH is adjusted to at least 8.8. The reactants are then heated to about 97 ℃ over a period of about 30 minutes while maintaining a pH of at least about 6.6. The temperature is then maintained at this level for about 15 minutes to maintain a pH of at least about 6.0. The reactor contents were then rapidly cooled to about 85 ℃ and held there until a Gardner-Holdt viscosity of "a" was achieved (about 45 minutes). After the "a" viscosity was reached, the reactor contents were cooled to about 65 ℃ and held at that level until the "D" viscosity was reached (about 20 minutes). During these two periods of time, the pH is maintained at a pH of at least about 4.7. Thereafter, the pH is adjusted to a pH range from about 7.7 to about 8.0 while adjusting and maintaining the temperature to about 60 ℃. Vacuum was applied to the reactor and about 11% of the weight of the batch in the kettle was distilled as quickly as possible. The viscosity was about "KL". After cooling to about 25 ℃, about 1 part triethylamine sulfate (also known as N, N-diethylethylamine sulfate as a latent catalyst) is added to the reactor contents. After about 10 minutes of mixing, the pH was adjusted to about 8.0. The final product had a refractive index of about 1.45 at 25 ℃.

Example 11

Preparation of Cyclic Urea prepolymers

a) A cyclic urea prepolymer having a urea to formaldehyde to ammonia (U: F: A) molar ratio of 1.0: 2.0: 0.5 is prepared by feeding formaldehyde, ammonia and urea to a reactor while maintaining the temperature below about 65 ℃. Once the reactants are in the reactor, the resulting solution is heated to about 90 ℃ for about 1 hour until the reaction is complete. Once the reaction was complete, the solution was cooled to room temperature. C¹³NMR showed approximately 42.1% of the urea contained in the triazineone ring structure, 28.5% of the urea was di/tri-substituted, 24.5% of the urea was mono-substituted, and 4.9% of the urea was free.

b) A second cyclic urea prepolymer was prepared in the same manner as a), except that the molar ratio was 1.0: 1.2: 0.5. C¹³NMR showed approximately 25.7% of the urea contained in the triazineone ring structure, 7.2% of the urea was di/tri-substituted, 31.9% of the urea was mono-substituted, and 35.2% of the urea was free.

c) A third cyclic urea prepolymer was prepared in the same manner as a), except that the molar ratio was 1: 3: 1 and it was heated to about 90 ℃ for about 1 hour and then cooled to 100 ℃ for 2 hours. C¹³NMR showed that approximately 76.0% of the urea was contained in the triazineone ring structure, 15.3% of the urea was di/tri-substituted, 8.1% of the urea was mono-substituted, and 0.6% of the urea was free.

d) A fourth cyclic urea prepolymer was prepared in the same manner as a), except that the molar ratio was 1: 4: 1 and it was heated to about 90 ℃ for about 3 hours and the pH was controlled at about 7.5. C¹³NMR showed approximately 79.2% of the urea contained in the triazineone ring structure, 17.7% of the urea was di/tri-substituted, 1.6% of the urea was mono-substituted, and 1.5% of the urea was free.

Example 12

Preparation of phenolic Binders modified with Cyclic Urea prepolymers and evaluation of the use of the Binders for fiberglass insulation

The following phenolic binders were prepared.

1) A pre-reacted system having a urea extension of 26% and a formaldehyde to ammonia molar ratio (F/A) of 1.14,

2) an unreacted system having a urea extension of 26% and a formaldehyde to ammonia molar ratio (F/A) of 1.14,

3) an unreacted system at a 26% fortification level and 1.14 (F/A) using the 1.0: 1.2: 0.5U: F: A system of example 1b

4) An unreacted system using the 1.0: 2.0: 0.5U: F: A system of example 1a at a reinforcement level of 26% and a (F/A) of 1.14,

5) an unreacted system using the 1.0: 1.2: 0.5U: F: A system of example 1a at a 50% fortification level with ammonia to produce 1.14 (F/A), and

6) an unreacted system using the 1.0: 2.0: 0.5U: F: a system of example 1a at 50% fortification level with ammonia to yield F/a ═ 1.14.

The composition of the binder is summarized in table 6.

TABLE 6

The resin had 7.4% free formaldehyde, 1.0% free phenol, a pH of 8.4 and 51% solids.

The formaldehyde released in each binder was tested using a tube oven method. A prepolymer was prepared by combining 145g of the resin with 65g of 40% urea. The prepolymer solution was allowed to pre-react overnight at room temperature (16 hours). These adhesives were prepared as summarized in table 1. The adhesive was weighed in a glass sample boat on a glass filter paper to the nearest 0.1 mg. The sample boat was then transferred to a tube furnace and cured at 200 ℃ for 10 minutes. Air from a tube furnace was bubbled through a 1: 1 solution of acetonitrile and water. The solution was derivatized with dinitrophenylhydrazine and analyzed on HPLC using a diode array detector to quantify formaldehyde hydrazone as a percentage of binder solids.

Handsheets were prepared by dusting the binder onto a glass mat, vacuum treating excess binder from the glass and curing the paper in a forced air oven at 205 ℃ for 1.5 minutes. Dry tensile was measured by breaking the handsheet on a tensile tester, hot/wet tensile was measured by soaking the handsheet in water at 85 ℃ for 10 minutes and then breaking them on a tensile tester while they were still hot and wet. The vent of the heating furnace is fitted with a tube to which a photometer is attached. Opacity or visible emission is determined from the% transmittance or% absorbance of the light. The results for opacity and formaldehyde release for all binders are shown in table 7.

TABLE 7

Example 13

Preparation of modified phenolic resins/adhesives with cyclic urea prepolymers and use of these adhesives in plywood

The methylolated cyclic urea prepolymer is prepared by reacting urea, ammonia and formaldehyde as previously described and further reacting with two moles of formaldehyde per mole of urea to produce a methylolated cyclic urea prepolymer having a solids level of 50%.

A) Resin A: the cyclic urea prepolymer is reacted with a standard phenolic resin during the heat-refining cycle of the phenolic resin. Phenol (1311g) was combined with 583g of formaldehyde (50%), 1217g of water, 500g of cyclic urea prepolymer, 16g of beaded starch, 1.5g of antifoam and 158g of caustic (50%). The initial charge of phenol and formaldehyde was adjusted to maintain a molar ratio of 0.8F/P during the first reaction stage. The reaction was allowed to exotherm to 79-80 ℃. Additional caustic (142g, 50%) was added and then 1033g of formaldehyde (50%) was added over 30 minutes. The reaction was allowed to exotherm to 97-98 ℃. The mixture was kept for 22 minutes before cooling to room temperature. The cyclic urea prepolymer comprised 9.5 wt% of the final resin.

The viscosity of the final resin was 944cps at 25 ℃, the solids content was 43.6 wt%, the caustic percentage was 5.9 wt%, the gel time was 25.7 minutes, the refractive index was 1.4643 and the molecular weights were Mn 279, Mw 693, and Mz 1407. The polydispersity is 2.482.

The resin a described above can be used in the present invention by itself or in combination with other resins (e.g. standard plywood resins) as described in the different blends below. These same resins and combinations can also be used as adhesives for plywood as follows. A standard plywood resin was used as a comparative resin and had a viscosity of 1146cps, solids content of 44 wt%, a caustic percentage of 5.9 wt%, a gel time of 24 minutes, a refractive index of 1.4646 and molecular weights by GPC of Mn 318, Mw 948 and Mz 2322.

B) Four binder mixtures were produced. The comparative binder mixture included 1) 17.5 wt% fresh water, 2)6.6 wt% Q-bond corn flour extender, 3) 7.6 wt% Co-Cob filler (furfural residue from waste agricultural sources), 4) 0.3 wt% sodium carbonate, 5) 3.0 wt% 50% caustic soda and 6) 65 wt% phenolic resin. Only standard plywood resin formed part of the control adhesive mix. The remaining blend replaced all or part of the standard plywood control resin with resin a.

Mix #1 standard plywood control resin.

Mix #2 standard plywood control resin in 50/50 weight ratio and resin a.

Mix # 3100% resin A

Mix # 438 g of resin A mixed with 743g of standard plywood control resin.

Mix # 575 g of resin A and 706g of standard plywood control resin.

Mix # 6154 g of resin A and 635g of a standard plywood control resin.

After the binder mixture is produced, the content of cyclic urea prepolymer increases in mixtures 4, 5 and 6. Hydroxymethylated cyclic urea prepolymer (35g) was added to mixture 4, 67g was added to mixture 5 and 137g was added to mixture 6. The formulation was modified to add a cyclic urea prepolymer that was not reacted into the resin by adjusting the solids contributed by the PF, filler and extender. These changes are presented in table 8 as total dry solids, total resin solids, and PF resin solids.

TABLE 8

The adhesive mixture provided above was applied to southern pine veneers and evaluated as the adhesive described in US patent No. 6,114,491, which provides details regarding the test parameters, percent wood breakage, and the role of the cyclic urea resin prepolymer, among others.

Claims (24)

1. A method for removing impurities from a slurry comprising bitumen, comprising:

a. providing a bitumen containing slurry comprising bitumen, water and at least one impurity;

b. aerating the slurry containing bitumen;

c. contacting the aerated bitumen-containing slurry with an amine-aldehyde resin, thereby providing:

i. a bottom product portion comprising a higher concentration of at least one impurity;

an intermediate product fraction comprising bitumen; and

a froth comprising bitumen, wherein the froth comprises a lower concentration of at least one impurity relative to the bitumen containing slurry; and is

d. Separating the bottom product portion from the intermediate product portion and the froth;

wherein the amine-aldehyde resin comprises a urea-formaldehyde resin prepared by the steps of:

mixing formaldehyde, urea, triethanolamine and optionally ammonia reactants at a basic pH, heating the mixture to an elevated temperature for a period of time sufficient to obtain complete methylolation of the urea, the reactants being present in an amount of from 1.50 to 4.0 moles of formaldehyde, 0.001 to 0.1 moles of triethanolamine and 0.0 to 0.5 moles of ammonia per mole of urea; and is

Acid is added to lower the pH to within the range of 4.9 to 5.2 and urea is added until the molar ratio of formaldehyde to urea is within the range of 1.5: 1 to 2.5: 1 and reacted for a time sufficient to remove free formaldehyde to less than 2%.

2. The method of claim 1, further comprising the step of contacting the intermediate portion and the froth from step d with additional amine-aldehyde resin, thereby reducing the concentration of at least one impurity in the intermediate portion relative to the bitumen-containing slurry.

3. The method of claim 1, further comprising recovering the bitumen from the froth.

4. A method of dewatering a coal-containing slurry, comprising:

a. providing a coal-containing slurry comprising coal and water;

b. contacting the coal-containing slurry with an amine-aldehyde resin, thereby separating the coal from the slurry; and is

c. Dewatering the separated coal by filtration, sedimentation or drying;

wherein the dewatering time of the separated coal is less than the dewatering time of a coal sample separated from a coal-containing slurry that is not in contact with an amine-aldehyde resin; and is

Wherein the amine-aldehyde resin comprises a urea-formaldehyde resin prepared by the steps of:

mixing formaldehyde, urea, triethanolamine and optionally ammonia reactants at a basic pH, heating the mixture to an elevated temperature for a period of time sufficient to obtain complete methylolation of the urea, the reactants being present in an amount of from 1.50 to 4.0 moles of formaldehyde, 0.001 to 0.1 moles of triethanolamine and 0.0 to 0.5 moles of ammonia per mole of urea; and is

Acid is added to lower the pH to within the range of 4.9 to 5.2 and urea is added until the molar ratio of formaldehyde to urea is within the range of 1.5: 1 to 2.5: 1 and reacted for a time sufficient to remove free formaldehyde to less than 2%.

5. The method of claim 4, wherein the contacting step further comprises contacting the coal-containing slurry in step b with silica, a polysiloxane, a polyvinyl alcohol, a flocculant, or any combination thereof.

6. The method of claim 5, wherein the flocculant is a silicate, a polysaccharide, or a polyacrylamide.

7. The method of claim 4, wherein the dehydrated coal comprises a reduced amount of moisture, an increased BTU value, or both relative to the coal in the coal-containing slurry.

8. A method for removing impurities from water, comprising:

a. providing impure water containing impurities selected from the group consisting of: solid particles, metal cations, or a combination thereof;

b. contacting the impure water with an amine-aldehyde resin, thereby suppressing the impurities from the impure water to provide purified water having a reduced concentration of impurities relative to the impure water; and is

c. Separating the impurities from the purified water;

wherein the amine-aldehyde resin comprises a urea-formaldehyde resin prepared by the steps of:

mixing formaldehyde, urea, triethanolamine and optionally ammonia reactants at a basic pH, heating the mixture to an elevated temperature for a period of time sufficient to obtain complete methylolation of the urea, the reactants being present in an amount of from 1.50 to 4.0 moles of formaldehyde, 0.001 to 0.1 moles of triethanolamine and 0.0 to 0.5 moles of ammonia per mole of urea; and is

Acid is added to lower the pH to within the range of 4.9 to 5.2 and urea is added until the molar ratio of formaldehyde to urea is within the range of 1.5: 1 to 2.5: 1 and reacted for a time sufficient to remove free formaldehyde to less than 2%.

9. The method of claim 8, wherein the contacting step further comprises contacting the impure water of step b with silica, a polysiloxane, a polyvinyl alcohol, a flocculant, or any combination thereof.

10. The method of claim 9, wherein the flocculant is a silicate, a polysaccharide, or a polyacrylamide.

11. The method of claim 8, wherein the metal cation impurities comprise As⁺⁵、 Pb⁺²、Cd⁺²、Cu⁺²、Mn⁺²、Hg⁺²、Zn⁺²、Fe⁺²Or any combination thereof.

12. The method of claim 8, wherein the solid particulate impurities comprise siliceous materials.

13. The method of claim 8, wherein the solid particulate impurities comprise clay, sand, or a cellulosic material.

14. The method of claim 8, wherein the water of step a is selected from sewage.

15. The method of claim 14, wherein the wastewater is a drilling fluid, a pulp and paper mill effluent, a clay-containing effluent, a coal-containing suspension, an intermediate to a bitumen production process, or a wastewater effluent from bitumen treatment.

16. A method for purifying a coal mine stone, comprising:

a. providing a coal mine stone comprising coal and one or more soluble or insoluble impurities;

b. contacting an aqueous slurry of coal mine stone with an amine-aldehyde resin prior to or during a size or density classification operation of the coal mine stone, and

c. separating purified coal from the aqueous slurry;

wherein the purified coal has a reduced amount of mercury, nitrogen, sulfur, silicon, ash, or pyrite relative to the coal mine ore, measured on a volatile-free weight basis; and is

Wherein the amine-aldehyde resin comprises a urea-formaldehyde resin prepared by the steps of:

mixing formaldehyde, urea, triethanolamine and optionally ammonia reactants at a basic pH, heating the mixture to an elevated temperature for a period of time sufficient to obtain complete methylolation of the urea, the reactants being present in an amount of from 1.50 to 4.0 moles of formaldehyde, 0.001 to 0.1 moles of triethanolamine and 0.0 to 0.5 moles of ammonia per mole of urea; and is

Acid is added to lower the pH to within the range of 4.9 to 5.2 and urea is added until the molar ratio of formaldehyde to urea is within the range of 1.5: 1 to 2.5: 1 and reacted for a time sufficient to remove free formaldehyde to less than 2%.

17. The method of claim 16, wherein the purified coal has a reduced amount of mercury, cadmium, lead, arsenic, or any compound thereof, as measured on a volatile-free weight basis relative to the coal mine ore.

18. The method of claim 16, wherein the purified coal has an amount of coal, nitrogen, sulfur, silicon, ash, or pyrite measured on a volatile-free weight basis that is less than a corresponding amount of a purified reference coal recovered in the size or density classification operation, wherein the aqueous slurry of reference coal ore is not contacted with the amine-aldehyde resin.

19. The method of claim 16, wherein the purified coal has a reduced moisture content, an increased BTU value, or both relative to the coal mine rock.

20. The method of claim 16, wherein the contacting step further comprises contacting the aqueous slurry of coal mine stone in step b with silica, a polysiloxane, a polyvinyl alcohol, a flocculant, or any combination thereof.

21. The method of claim 20, wherein the flocculant is a silicate, a polysaccharide, or a polyacrylamide.

22. The method of claim 16, wherein the reaction mixture of formaldehyde, urea, triethanolamine, and ammonia is heated to a temperature of about 95 ℃ over a period of 30 minutes and held at a temperature of 95 ℃ for 15 to 20 minutes.

23. The method of claim 16, wherein the amine-aldehyde resin comprises a resin having a number average molecular weight (M) of 300 g/mole to 4000 g/mole_n) Urea-formaldehyde resin of (a).

24. The method of claim 16, wherein the amine-aldehyde resin is further modified with an anionic functional group.