HK1118029B - Modified amine-aldehyde resins and uses thereof in separation processes - Google Patents

Description

Modified amine-aldehyde resins and their use in separation processes

CROSS-REFERENCE TO RELATED APPLICATIONS

The priority of the present application for united states provisional patent application 60/638,143, filed on 23/12/2004 and 60/713,339, filed on 2/9/2005, are hereby incorporated by reference in their entirety.

Technical Field

The present invention relates to modified resins for use in separation processes, particularly for the selective separation of solid and/or ionic species (e.g., metal cations) from aqueous media. Such processes include froth flotation (e.g. for mineral separation), separation of drill cuttings from petroleum drilling fluids, dewatering of clay and coal slurries, sewage treatment, treatment of pulp and paper mill effluents, removal of sand from bitumen and purification of water to make it potable. The modified resin includes a base resin that is the reaction product of a primary or secondary amine and an aldehyde (e.g., urea formaldehyde resin). The base resin is modified with a coupling agent (e.g., a substituted silane) during or after its preparation.

Background

Froth flotation

The industry is quite common with processes for purifying suspensions or dispersions, especially aqueous suspensions or dispersions, to remove suspended solid particles. For example, froth flotation is a separation process based on the different binding tendencies of various substances to ascending gas bubbles. Additives are often added to the froth flotation solution to improve the selectivity of the process. For example, "collectors" can be used to chemically and/or physically absorb minerals (e.g., those containing useful metals) to be floated, rendering them more hydrophobic. On the other hand, the "depressants" typically used in conjunction with collectors make other materials (e.g., gangue minerals) less likely to bind to the gas bubbles and therefore be entrained in the foam concentrate.

In this manner, some materials (e.g., useful minerals or metals) exhibit a preferential affinity for air bubbles relative to other materials (e.g., gangue minerals), causing them to rise to the surface of the aqueous slurry where they can be collected in the foam concentrate. Thereby achieving the degree of separation. In a special case, so-called reverse froth flotation, the gangue is preferentially floated and concentrated at the surface, and the desired material is removed at the bottom. Gangue materials typically refer to 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 comprises mainly this material, while a lesser amount of impurities is preferentially floated. For example, in the beneficiation of kaolin, a material used in large quantities in industry, iron and titanium oxides can be separated from impure, clay-containing ores by flotation, leaving a purified kaolin bottom product.

Although the manner in which known collectors and inhibitors achieve their efficacy has not been fully determined, several theories have been proposed. For example, inhibitors may prevent gangue minerals from adhering to the useful minerals to be separated, or they may even prevent collectors from absorbing on the gangue minerals. Whatever the mechanism, the ability of an inhibitor to increase selectivity in a froth flotation process can very favorably impact its economics.

Froth flotation is generally used in the beneficiation of a variety of useful materials (e.g. minerals and metal ores, even high molecular weight hydrocarbons such as bitumen) in order to separate them from unwanted impurities which are inevitably simultaneously extracted from natural deposits. In the case of solid ore beneficiation, froth flotation generally involves grinding raw ore into sufficiently small dispersed particles of the useful mineral or metal, and then contacting an aqueous "slurry" of the ground ore with rising gas bubbles, usually while agitating the slurry. Prior to froth flotation, the raw ore may be subjected to any number of pre-treatment steps including selective crushing, screening, desliming, gravity concentration, electrical separation, low temperature roasting and magnetic differentiation.

Another particular froth flotation process of industrial importance involves the separation of bitumen from sand and/or clay, which is ubiquitous in oil sands deposits such as those found in the vast Athabasca region of Alberta, canada. Bitumen is considered a useful source of "semi-solid" petroleum or heavy hydrocarbon-containing crude oil that can be processed into many useful end products including transportation fuels such as gasoline or even petrochemicals. The oil sands reservoir of Alberta is estimated to contain 1.7 trillion barrels of crude oil containing bitumen, exceeding the reserves of the entire Saudi Arabia. Accordingly, significant efforts have recently been made to develop economically viable operations for the recovery of bitumen, primarily based on subjecting an aqueous slurry from which oil sands are extracted to froth flotation. For example, the "Clark process" involves recovering bitumen in a foam concentrate while suppressing sand and other solid impurities.

A variety of gangue depressants are known in the art for improving froth flotation separation, including sodium silicate, starch, tannic acid, dextrin, lignosulfonic acid, carboxymethyl cellulose, cyanide salts, and many others. Newly identified synthetic polymers have been found to be advantageous in particular beneficiation processes. For example, U.S. Pat. No. re.32,875 describes the use of phenolic copolymers (e.g. phenolic a, novolaks) or modified phenolic polymers (e.g. melamine modified novolaks) as inhibitors to separate gangue from phosphate minerals (e.g. apatite).

U.S. patent 3,990,965 describes the separation of iron oxide from bauxite using a water-soluble, low chain length prepolymer as an inhibitor, selectively adhering to the gangue and further polymerizing to give a crosslinked, insoluble resin.

Us patent 4,078,993 describes the separation of sulphides or oxidised sulphide ores (e.g. pyrite, pyrrhotite or sphalerite) from metal ore (e.g. copper, zinc, lead, nickel) using as inhibitors solutions or dispersions of low molecular weight condensation products of aldehydes with compounds containing 2 to 6 amine or amide groups.

Us patents 4,128,475 and 4,208,487 describe the separation of gangue materials from mineral ores using conventional frothers (e.g. pine oil) in combination with (preferably alkylated) amine-aldehyde resins which may have free methylol groups.

Us patent 4,139,455 describes the use of amine compounds (e.g. polyamines) as inhibitors to separate sulphides or oxidised sulphide ores (e.g. pyrite, pyrrhotite or sphalerite) from metal ore (e.g. copper, zinc, lead, nickel), at least 20% of the total amount of amine groups in the amine compounds being tertiary amine groups, and wherein the number of quaternary ammonium groups is from 0 to no more than 1/3 the number of tertiary amine groups.

Us patent 5,047,144 describes the separation of siliceous minerals (e.g. feldspar) from minerals (e.g. kaolinite) using as inhibitors a polyamide plastic template in combination with a reactive cationic condensation product of formaldehyde in combination with a reactive cationic surfactant (e.g. an organic alkylamine) or a reactive anionic surfactant (e.g. a long chain alkyl sulphonate).

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

Russian patents 2,169,740, 2,165,798 and 724,203 describe the inhibition of clay carbonate slimes from ores including sylvite (KCl-NaCl) ores in the potassium industry. The inhibitor used was a urea/aldehyde condensation product modified with polyethylene polyamine. In addition, guanidine-aldehyde 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 hydrophilic activity of Urea-Formaldehyde resin on Carbonate Clay impurities in Potassium ore (Study of the hydrophilizing Action of Urea-Formaldehyde resin on Urea-Formaldehyde resins on Carbonate Clay Impuritizisin Potasaium Ores), Inst.Obshch.Neorg.Khim, USSR, Vestsi Akademii NavukBSSR, Seryya Khimicinkh Navuk (1980); the Effect of Urea-Formaldehyde resins in Potassium ore Flotation (Effect of Urea-Formaldehyde resins on the Flotation of Potassium Ores), Khimicheskaya promyslenost, Moscow, Russian Federation (1980); and Adsorption of Urea-Formaldehyde resins to clay Minerals of Potassium Ores (Adsorption of Urea-Formaldehyde resins on clay Minerals of Potassium Ores), inst. obshch new.

As is known in the art, a wide variety of materials can be beneficiated/refined by froth flotation. Likewise, the properties of the desired and undesired components vary widely. This is due to the different chemical compositions of these materials, as well as the variety of previous chemical treatments and the processing steps used. Thus, the number and type of froth flotation depressants is relatively broad.

Moreover, the use of a particular inhibitor in one installation (e.g., the beneficiation of raw potassium ore) does not predict that it will be equally effective in applications involving significantly different feedstocks (e.g., bituminous oil sands). The same applies to the use of inhibitors which are effective in froth flotation, which cannot be expected to be effective in separating solid impurities from aqueous suspensions of any of the types described below (and vice versa). The theoretical mechanisms underlying froth flotation and aqueous liquid/solid separation are clearly different, the former process relying on differences in hydrophobicity and the latter on several other possibilities (charge instability/neutralization, agglomeration, host-guest theory (including multidentate coordination), 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.). Inhibitors such as guar gum used for the beneficiation of metal ores in froth flotation cannot be used as dewatering agents, or even as inhibitors in froth flotation for bitumen separation. Moreover, in both applications described below (waste clay and coal dewatering), there is currently no reagent for improving solid/liquid separation. In general, despite the large amounts of flotation depressants and dewatering agents in the art, in many cases, even in the case of froth flotation, it is difficult to achieve a sufficient degree of clarification when two or more successive "coarse" and "fine" flotations are used. There is therefore a need in the art for agents that can be effectively used in a wide range of separation processes including froth flotation and the separation of solid impurities from suspensions.

Other separations

Other processes for separating solid impurities from suspensions besides froth flotation may include the use of additives that destabilize these suspensions or coagulate the impurities into larger agglomerates. For example, agglomeration refers to the separation of the charge of suspended solid particles by neutralization, rendering them unstable. Flocculation refers to bridging or agglomerating solid particles together into clumps or floes, thereby facilitating their separation by settling or flotation, depending on the density of the floe relative to the liquid. Filtration may additionally be used as a means of separating larger floes.

The above additives, especially flocculants, are commonly used, for example, in the separation of solid particles of rock or drill cuttings from oil and gas well drilling fluids. These drilling fluids (also commonly referred to as "drilling muds") are important in the drilling process for several reasons, including cooling and lubricating the drill bit, creating a fluid back pressure that prevents fluids formed from high pressure oil, gas and/or water from prematurely entering the well, preventing the exposed wellbore from collapsing. The drilling mud, whether water-based 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 agglomerate these cuttings at the surface of the circulating drilling mud, thereby separating them from the drilling mud.

Other uses of flocculants in solid/liquid separation include agglomerating clay suspended in the bulk waste slurry effluent from phosphate production plants. Flocculants, such as natural or synthetic anionic polymers, which may be mixed with fibrous materials such as recycled newsprint, are often used for this purpose. The aqueous clay slurry formed in the phosphate purification unit typically has a flow rate of greater than 100,000 gallons per minute and typically contains less than 5 wt.% solids. Dehydration (or precipitation) of such waste clays to recycle water is one of the most difficult problems associated with recovery. The settling ponds used for this dewatering typically constitute about half a mine area, and dewatering times can be on the order of months to years.

Other particular applications of industrial importance in the separation of solids from aqueous liquids include filtration of coal from aqueous slurries (i.e., coal slurry dewatering), treatment of wastewater by settling to remove impurities (e.g., sludge), and treatment of pulp and paper mill wastewater to remove suspended cellulosic solids. Dehydration of coal is a significant industrial problem because the BTU value of coal decreases with increasing water content. Industrial and municipal untreated sewage requires significant treatment capacity, for example waste produced by the us population is collected in sewer systems and carried by 140 billion gallons of water per day. Paper industry waste streams are also large solids-containing aqueous liquids, and a typical paper mill produces waste streams that typically exceed 2500 million gallons per day. As mentioned above, the removal of sand from the aqueous bitumen-containing slurry produced in the extraction and subsequent treatment of oil sands presents another great challenge for large-scale production in terms of the purification of the aqueous suspension. Furthermore, removal of suspended solid particulates is often an important consideration in the purification of water, for example in the preparation of drinking (i.e. potable) water. Synthetic polyacrylamides and naturally occurring hydrocolloid polysaccharides such as alginates (copolymers of D-mannuronic and L-guluronic acids) and guar gum are flocculants in such devices.

The above applications thus provide several specific examples relating to the treatment of aqueous suspensions to remove solid particles. However, such separations are common in a wide variety of other processes in the mining, chemical, industrial and municipal waste, sewage treatment and paper industries, as well as in a wide variety of other water consuming industries. Thus, there is a need in the art for additives that are effective in facilitating the selective separation of a wide variety of solid impurities from liquid suspensions. Advantageously, such agents should be selective in terms of chemical interaction with solid impurities, facilitating the removal of these impurities by coagulation, flocculation or other mechanisms. Particularly desirable are additives that are also capable of complexing undesirable ionic species such as metal cations to also facilitate their removal.

Disclosure of Invention

All applications

The present invention relates to modified resins for removing a wide variety of solid and/or ionic species suspended and/or dissolved in liquids, typically in a selective manner. These modified resins are particularly useful as froth flotation depressants in the beneficiation of a wide variety of materials, including minerals and metal ores (e.g., the beneficiation of kaolin). The modified resins may also be used to treat aqueous suspensions (e.g., aqueous suspensions containing sand, clay, coal and/or other solids, such as cutting fluids of waste drilling rigs, and process and waste streams in the production of phosphate and coal, sewage treatment, paper making, or asphalt recycling equipment) to remove solid particles and possibly metal cations (e.g., in the purification of drinking water). The modified resin comprises a base resin modified with a coupling agent that is highly selective for binding solid impurities, particularly siliceous materials such as sand or clay.

Froth flotation

Without being limited by theory, the coupling agent has a high degree of selectivity in froth flotation separations combined with gangue or desired materials (e.g., kaolin clay), particularly siliceous gangue materials (e.g., sand or clay). Also, since the base resin has hydrophilicity, substances interacting or binding with the coupling agent are effectively isolated in the aqueous phase in the froth flotation process. Thus, the gangue materials can be selectively separated from the useful minerals (e.g., minerals, metals, or bitumen) or the clay-containing ore impurities (e.g., iron oxide and titanium oxide) sequestered in the foam concentrate.

Accordingly, in one embodiment, the present invention is a process for the beneficiation of ore. The method includes treating a slurry of ore particles with an inhibitor comprising a modified resin. The modified resin includes a base resin that is a reaction product of a primary or secondary amine and an aldehyde, the base resin being modified with a coupling agent. The ore slurry treatment may be performed before or during froth flotation. In one embodiment, the ore includes sand or clay impurities, typically ore recovered in phosphate or potash ores. In another embodiment, the base resin is a urea formaldehyde resin. In another embodiment, the coupling agent is selected from the group consisting of substituted silanes, silicates, silicas, polysiloxanes, and mixtures thereof.

In another embodiment, the invention is a froth flotation depressant for beneficiating a useful material, the useful material including a mineral or a valuable metal ore. The inhibitor comprises a solution or dispersion of a modified resin having a resin solids content of about 30 wt.% to about 90 wt.%. The modified resin includes a base resin that is the reaction product of a primary or secondary amine and an aldehyde. The base resin is modified with a coupling agent. The coupling agent is present in an amount of about 0.1 wt.% to about 2.5 wt.% of the solution or dispersion having a resin solids content of about 30 wt.% to about 90 wt.%

wt.%. In another embodiment, the base resin is a urea-formaldehyde resin, which is 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 coupling agent is a substituted silane selected from the group consisting of: ureido (ureido) substituted silanes, amino substituted silanes, sulfur substituted silanes, epoxy substituted silanes, methacryl substituted silanes, vinyl substituted silanes, alkyl substituted silanes, haloalkyl substituted silanes.

In another embodiment, the invention is a process for purifying clay from clay-containing ores comprising impurities selected from the group consisting of metals, metal oxides, minerals, and mixtures thereof. The process comprises treating the clay-containing ore slurry with an inhibitor comprising a modified resin, recovering purified clay by froth flotation of impurities after or during the treatment step, the content of at least one impurity in the purified clay being reduced. The modified resin includes a base resin that is the reaction product of a primary or secondary amine and an aldehyde. The base resin is modified with a coupling agent. In another embodiment, the clay-containing ore comprises kaolin. In another embodiment, the impurities comprise a mixture of iron oxide and titanium dioxide. In another embodiment, the impurities comprise coal.

In another embodiment, the invention is a method of purifying bitumen from a bitumen-containing slurry comprising sand or clay. The process comprises treating the slurry with an inhibitor comprising a modified resin as described above and recovering purified bitumen in which the sand or clay content is reduced by froth flotation after or during the treatment step.

Other separations

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

In another embodiment, the invention is a method for purifying water containing metal cations. The method comprises treating the water with the above-described modified resin and removing 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 As⁵⁺、pb²⁺、Cd²⁺、Cu²⁺、Mn²⁺、Hg²⁺And mixtures thereof. In yet another embodiment, the base resin is further modified with anionic functional groups.

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

Drawings

FIG. 1 shows the performance of silane coupling agent modified urea formaldehyde resins having molecular weights in the range of 400-1200 g/mole in the flotation of milled potassium ore samples. This property is given in comparison to the unmodified (i.e. no silane coupling agent added) resin and the guar gum control.

Detailed Description

All applications

The modified resin used in the separation process of the present invention is a resin comprising a base resin which is the reaction product of a primary or secondary amine and an aldehyde. Having nitrogen atoms that are not fully substituted (i.e., not part of a tertiary or quaternary amine), primary or secondary amines can react with aldehydes to form adducts. If formaldehyde is used as the aldehyde, for example, the adduct is a methylolated adduct having reactive methylol functionality. Typical primary and secondary amines used to form the base resin include compounds having at least two functional amine or amide groups, or amidine-based compounds having at least one of each of these groups. Such compounds include urea, guanidine, and melamine, each of which may be substituted at the amine nitrogen position with an aliphatic or aromatic group, wherein at least two of the nitrogen atoms are not fully substituted. Primary amines are generally used. Urea is representative of these primary amines since it is inexpensive and readily available. In the case of urea, if desired, at least a portion thereof may be replaced with ammonia, primary alkylamines, alkanolamines, polyamines (e.g., alkyl primary diamines such as ethylenediamine and alkyl primary triamines such as diethylenetriamine), polyalkanolamines, triazines substituted with melamine or other amines, dicyandiamide, substituted ureas or cyclic ureas (e.g., ethyleneurea), primary, secondary and alkylamines, quaternary and alkylamines, guanidine, and derivatives of guanidine (e.g., cyanoguanidine and acetoguanidine). Aluminum sulfate, cyclic phosphates and phosphates, formic acid or other organic acids may also be used with urea. The amount of any of these components (or their combined amounts if used in combination) is typically from about 0.05 wt.% to about 20 wt.% of the resin solids if incorporated into the resin in place of a portion of the urea. Those skilled in the art will appreciate that these types of agents have improved hydrolysis resistance, flexibility, reduced aldehyde volatility, and other properties.

The aldehyde used to react with the primary or secondary amine to form the base resin may be formaldehyde, or other aliphatic aldehydes such as acetaldehyde and propionaldehyde. Aldehydes also include aromatic aldehydes (e.g., benzaldehyde and furfural), as well as other aldehydes, such as aldol, glyoxal, and crotonaldehyde. Mixtures of aldehydes may also be used. Typically, formaldehyde is used because it is convenient to purchase and relatively inexpensive.

The formation of adducts between amines and aldehydes is initially known in the art during the formation of base resins. The rate of aldehyde addition reaction is generally highly dependent on the pH and the degree of substitution obtained. For example, the ratio of the rates of addition of formaldehyde to urea to form one, two and three methylol groups in sequence is estimated to be 9: 3: 1, whereas quaternary methylolaldehydes are not normally produced in effective amounts. The adduct-forming reaction is generally carried out at an advantageous rate under basic conditions and thus in the presence of a suitable basic catalyst, such as ammonia, an alkali metal hydroxide or an alkaline earth metal hydroxide. Sodium hydroxide is most commonly used.

At sufficiently high pH, the adduct formation reaction can be carried out substantially without a condensation reaction that increases the molecular weight of the resin by polymerization, i.e., to raise the resin (advance). However, in order to form the low molecular weight condensation resin from further reaction of the amine-aldehyde adduct, the pH of the reaction mixture is typically maintained at greater than 5, typically from about 5 to about 9. If desired, an acid such as acetic acid may be added to help control the pH and thus the rate of condensation and thus the molecular weight of the final condensation resin. The reaction temperature is typically in the range of from about 30 ℃ to about 120 ℃, usually below about 85 ℃, and reflux temperatures are typically used. In the preparation of low molecular weight amine-aldehyde condensation resins from primary or secondary amines and aldehyde starting materials, reaction times of from about 15 minutes to about 3 hours, typically from about 30 minutes to about 2 hours, are employed.

Various additives may be added prior to or during the condensation reaction to provide the desired properties to the final modified amine-aldehyde resin. Such as 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 amine-aldehyde resins, which when used to prepare modified amine-aldehyde resins can improve the performance of froth flotation and other applications. Further, diallyl dimethyl ammonium chloride (or analogues thereof, e.g. diallyl diethyl ether) is includedAmmonium chloride) or an alkylating agent containing epichlorohydrin (or an analog thereof, such as epibromohydrin) can be used to increase the cationic charge of the amine-aldehyde resin condensate, which can improve performance in certain solid/liquid separations (e.g., clay dehydration) described below when used to prepare modified amine-aldehyde resins. In this manner, such additives can react more efficiently into the modified amine-aldehyde resin than if mixed with the resin only after preparation.

The condensation reaction products of the above amine-aldehyde, amide-aldehyde and/or amidine-aldehyde adducts include, for example, those obtained by: (i) formation of methylene bridges between amino nitrogens by reaction of alkanol groups and amino groups, (ii) formation of methylene ether linkages by reaction of two alkanol groups, (iii) formation of methylene linkages by subsequent removal of formaldehyde from methylene ether linkages, and (iv) formation of methylene linkages by subsequent removal of water and formaldehyde from alkanol groups.

Generally, the molar ratio of aldehyde to primary or secondary amine in the base resin preparation is from about 1.5: 1 to about 4: 1, which refers to the ratio of the molar amount of all aldehydes to the molar amount of all amines, amides and amidines that participate in the reaction to prepare the base resin during the above adduct formation and the above condensation reaction, whether the reactions are conducted separately or simultaneously. The resins are generally prepared at atmospheric pressure. The viscosity of the reaction mixture is often used to conveniently represent the molecular weight of the resin. Thus, the condensation reaction can 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 can be removed by vacuum distillation to give the resin the desired solids content. Any of a variety of conventional methods for reacting primary and secondary amines and aldehyde components may be employed, such as staged monomer addition, staged catalyst addition, pH control, amine modification, and the like, although the invention is not limited to any particular method.

A representative base resin for the separation process of the present invention is urea formaldehyde resin. As noted above, other reactive amines and/or amides can be substituted for a portion of the urea, and other aldehydes can be substituted for a portion of the formaldehyde, providing various desired properties without departing from the characteristics of the base resin as a urea-formaldehyde resin. When used as a base resin, the urea-formaldehyde resin may be prepared from urea and formaldehyde monomers or from precondensates in a manner well known to those skilled in the art. Generally, urea and formaldehyde are reacted in a molar ratio of formaldehyde to urea (F: U) of from about 1.75: 1 to about 3: 1, and generally from about 2: 1 to about 3: 1, to provide sufficient methylolated species (e.g., di-or tri-methylolated ureas) for resin crosslinking. In general, urea-formaldehyde resins are highly water-dilutable dispersions, otherwise aqueous solutions.

In one embodiment, the condensation is carried out to an extent such that the urea formaldehyde base resin has a number average molecular weight (Mn) of greater than about 300 grams/mole, typically from about 400 to about 1200 grams/mole. As is known in the art, the Mn value of a polymer sample having a molecular weight distribution is defined as

Here N_iIs the number of polymers having repeating units of i, and M_iIs the molecular weight of the polymer having repeating units i. The number average molecular weight is generally determined using Gel Permeation Chromatography (GPC), and the solvents, standards and procedures used are well known to those skilled in the art.

Cyclic urea-formaldehyde resins may also be utilized and prepared, for example, as described in U.S. patent 6,114,491. The urea, formaldehyde and ammonia reactants are used in a molar ratio of urea to formaldehyde to ammonia of about 0.1 to 1.0 to about 0.1 to 3.0 to about 0.1 to 1.0. These reactants are charged to the reaction vessel while maintaining a temperature below about 70 ℃ (160 ° F), typically about 60 ℃ (140 ° F). The order of addition is not critical, but it is important to be careful during the addition of ammonia to formaldehyde (or during the addition of formaldehyde to ammonia) because of the exothermic reaction. In fact, due to the intense exotherm, it is preferred to add formaldehyde and urea first, followed by ammonia. This sequence of addition allows one to take advantage of the endotherm caused by the addition of urea to water, increasing the rate of ammonia addition. Alkali may be required to maintain alkaline conditions throughout the cooking process.

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

The yield is typically about 100%. The cyclic urea resins typically comprise at least 20% of the 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 reactants. For example, a cyclic urea resin having a molar ratio of 1.0: 2.0: 0.5U: F: A obtained in solution is passed through C¹³-NMR characterization, containing approximately 42.1% cyclic urea, 28.5% di/tri-substituted urea, 24.5% mono-substituted urea and 4.9% free urea. Cyclic urea resin obtained in solution with a molar ratio 1.0: 1.2: 0.5U: F: A was passed through C¹³-NMR characterization, containing approximately 25.7% cyclic urea, 7.2% di/tri-substituted urea, 31.9% mono-substituted urea and 35.2% free urea.

Alternatively, the cyclic urea-formaldehyde resin may be prepared by a method such as that described in U.S. patent 5,674,971. Cyclic urea resins are prepared by reacting urea and formaldehyde in at least two and optionally three steps. The first step is carried out under alkaline reaction conditions, and urea and formaldehyde are reacted in the presence of ammonia at a molar ratio of F/U of 1.2: 1 to 1.8: 1. The ammonia is supplied in an amount sufficient to produce an ammonia/urea molar ratio of about 0.05: 1 to about 1.2: 1. The mixture reacts to form a cyclic triazinone/triazine or a cyclic urea resin.

Water-soluble triazinone compounds can also be prepared by reacting urea, formaldehyde and a primary amine as described in U.S. Pat. Nos. 2,641,584 and 4,778,510. These patents also describe suitable primary amines such as, but 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 cyclic urea-formaldehyde resins or urea-formaldehyde resins, the skilled practitioner will recognize that many forms of urea and formaldehyde are commercially available. Any form of reactant and reaction product that is sufficiently reactive and does not introduce an extraneous deleterious moiety into the desired reaction can be used in the preparation of urea-formaldehyde resins useful in the present invention. For example, common forms of use for formaldehyde include polyoxymethylene (solid, polymerized formaldehyde) and formalin solutions (aqueous formaldehyde solutions at 37%, 44% or 50% formaldehyde concentration, sometimes with methanol). Formaldehyde can also be obtained in gaseous form. Any of these forms is suitable for use in preparing the urea formaldehyde base resin. Typically, formalin solutions are used as the formaldehyde source. To prepare the resin of the present invention, any of the above aldehydes (e.g., glyoxal) may be used in place of, in whole or in part, methanol.

Similarly, urea is generally available in a variety of forms. Solid urea, such as prill, and urea solutions (typically aqueous solutions) are commercially available. Any form of urea is suitable for use in the practice of the present invention. For example, a number of commercially prepared urea-formaldehyde solutions may be used, including urea-formaldehyde combination products such as the urea-formaldehyde condensates (e.g., UFC 85) disclosed in U.S. Pat. nos. 5,362,842 and 5,389,716.

In addition, urea-formaldehyde Resins such as the types sold by Georgia Pacific Resins, Inc., Borden Chemical Co., and Neste Resins Corporation may be used. These resins are made as low molecular weight condensates or adducts containing reactive methylol groups capable of undergoing condensation to form resinous polymers as described above, often within the aforementioned number average molecular weight ranges. The resins typically contain small amounts of unreacted (i.e., free) urea and formaldehyde, as well as cyclic ureas, mono-methylolated ureas, and bis-and tris-methylolated ureas. The relative amounts of these species may vary depending on the preparation conditions (e.g., the molar ratio of formaldehyde to urea used). The balance of these resins are typically water, ammonia and formaldehyde. Various additives known in the art including stabilizers, curing accelerators, fillers, extenders, and the like may also be added to the base resin.

The modified resin of the present invention is prepared by modifying a base resin as described above with a coupling agent having a high binding selectivity to unwanted solid materials (e.g., sand or clay) and/or ionic species (e.g., metal cations) to be separated in the separation/purification process of the present invention. Without being limited by theory, in one embodiment, the coupling agent is believed to enhance the properties of the base resin, which is generally cationic (i.e., carries more positive than negative overall charge), attracting the majority of the clay surfaces, which are generally anionic (i.e., carries more negative than positive overall charge). These differences in electronic properties between the base resin and the clay can create mutual attraction at multiple locations, possibly even sharing electrons to form covalent bonds. It is possible to explain the positive-negative charge interactions that cause clay particles to be attracted to the base resin by several theories, such as host-guest theory (including multidentate coordination), 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 the bond, and the like.

The coupling agent may be added before, during or after the adduct-forming reaction of the primary or secondary amine with the aldehyde as described above. For example, the coupling agent may be added after the amine-aldehyde adduct is formed under basic conditions but before the pH of the adduct is lowered (e.g., by the addition of an acid) to effect the condensation reaction. Typically, a covalent bond is formed between the coupling agent and the base resin by a reaction between the base resin reactive functional group of the coupling agent and a portion of the base resin.

The coupling agent may also be added after the condensation reaction that produces the small molecular weight polymer. For example, the coupling agent may be added after raising the pH of the condensate (e.g., by adding a base) to stop the condensation reaction. Advantageously, it has been found that the base resin can be sufficiently modified by incorporating a coupling agent in the resin condensate at alkaline pH values (i.e., pH greater than 7) without appreciably increasing the molecular weight of the resin. Typically, the resin condensate is present as an aqueous solution or dispersion of the resin. When a substituted silane is used as a coupling agent, it is effective in modifying a base resin under alkaline conditions at normal or high temperatures. Any temperature associated with adduct formation or condensate formation during the preparation of the base resin as described above is suitable for incorporation of the silane coupling agent to modify the base resin. Thus, the coupling agent may be added to the amine-aldehyde mixture, adduct or condensate at ambient temperatures to about 100 ℃. Generally, elevated temperatures of from about 35 ℃ to about 45 ℃ are used to achieve the desired rate of reaction between the base resin reactive groups of the substituted silane and the base resin itself. For the aforementioned resin condensation reaction, the extent of the reaction can be monitored by the increase in viscosity of the resin solution or dispersion over time.

Alternatively, in some cases, the silane coupling agent may be added to a base resin-containing liquid (e.g., a froth flotation slurry) to be purified in order to modify the base resin in situ.

Representative coupling agents that are capable of modifying the base resin of the present invention and that have the desired binding selectivity or affinity for impurities (e.g., sand, clay) and/or ionic species include substituted silanes having a base resin reactive group (e.g., an organic functional group) and a second group (e.g., a trimethoxy silane group) that is capable of binding to or interacting with unwanted impurities (particularly siliceous materials). Without being limited by theory, the second group can aggregate these impurities into larger particles or flocs (i.e., by flocculation) upon treatment with the modified resin. This facilitates its removal. In the case of ore froth flotation separation, the second group of the coupling agent promotes the sequestration of gangue impurities or desirable materials (e.g., kaolin) in the aqueous phase into which the base resin may be dissolved or to which the base resin has a higher affinity. This facilitates separation of the useful material from the aqueous phase by flotation using a gas (e.g. air).

Representative base resin reactive groups of silanes include, but are not limited to: a ureido-containing moiety (e.g., a ureidoalkyl group), an amino-containing moiety (e.g., an aminoalkyl group), a sulfur-containing moiety (e.g., a mercaptoalkyl group), an epoxy-containing moiety (e.g., a fully hydrated glycidoxyalkyl group), a methacryloyl-containing moiety (e.g., a methacryloxyalkyl group), a vinyl-containing moiety (e.g., a vinylbenzylamino group), an alkyl-containing moiety (e.g., a methyl group), or a haloalkyl-containing moiety (e.g., a chloroa. Representative substituted silane coupling agents of the present invention thus include ureido substituted silanes, amino substituted silanes, sulfur substituted silanes, epoxy substituted silanes, methacryloyl substituted silanes, vinyl substituted silanes, alkyl substituted silanes, and haloalkyl substituted silanes.

The silane coupling agent may also be substituted with more than one base resin reactive group. For example, the tetravalent silicon atom in the silane coupling agent may be substituted with two or three base resin reactive groups, respectively, as described above. Alternatively, or in addition to, substitution with multiple base resin reactive groups, the silane coupling agent may also have multiple silane functional groups to increase the bonding strength or ability of the coupling agent to gangue contaminants (e.g., sand) or desired materials (e.g., kaolin). The degree of silanization of the silane coupling agent may be increased by, for example, adding additional silane groups to the coupling agent or crosslinking the coupling agent with additional silane-containing monomers. The use of multiple silane functional groups can even result in different orientations between the coupling agent and the clay surface (e.g., affinity between the clay surface and multiple silane groups on the "side" of the coupling agent as opposed to affinity between individual silane groups on the "head" of the coupling agent).

The silane coupling agent also includes a second group as described above, which as described above includes the silane portion of the molecule, typically substituted with one or more groups selected from: alkoxy (e.g., trimethoxy), acyloxy (e.g., acetoxy), alkoxyalkoxy (e.g., methoxyethoxy), aryloxy (e.g., phenoxy), aroyloxy (e.g., benzoyloxy), heteroaryloxy (e.g., furfuryloxy), haloaryloxy (e.g., chlorophenoxy), heterocycloalkoxy (e.g., tetrahydrofurfuryloxy), and the like. Thus, representative silane coupling agents having a base resin reactive group and a second group (e.g., a gangue reactive group) as described above for modifying a base resin include ureidopropyltrimethoxysilane, ureidopropyltriethoxysilane, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminopropylmethyldiethoxysilane, aminopropylmethyldimethoxysilane, aminoethylaminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane, diethylenetriaminopropyltrimethoxysilane, diethylenetriaminopropyltriethoxysilane, diethylenetriaminopropylmethyldimethoxysilane, diethylenetriaminopropylmethyldiethoxysilane, cyclohexylaminopropyltrimethoxysilane, hexamethylenediaminomethyltriethoxysilane, urethanesulfoxy silane, urethanesulfuro, Anilinomethyltrimethoxysilane, anilinomethyltriethoxysilane, diethylaminomethyltriethoxysilane, (diethylaminomethyl) methyldiethoxysilane, methylaminopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, bis (triethoxysilylpropyl) disulfide, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, mercaptopropylmethyldimethoxysilane, 3-thiocyanatopropyltriethoxysilane, isocyanatopropyltriethoxysilane, glycidoxypropyltrimethoxysilane, glycidoxypropyltriethoxysilane, glycidoxypropylmethyldiethoxysilane, glycidoxypropylmethyldimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, glycidoxypropyltriethoxysilane, di (diethylaminomethyl) triethoxysilane, di (diethylaminomethyl) methyldimethoxysilane, di (n-ethyl) trimethoxysilane, di (n-ethyl) triethoxysilane, di (n-ethyl) disulfide, di (n-ethyl) trimethoxysilane, di, Methacryloxypropylmethyldimethoxysilane, chloropropyltrimethoxysilane, chloropropyltriethoxysilane, chloromethyltriethoxysilane, chloromethyltrimethoxysilane, dichloromethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, vinyltriacetoxysilane, alkylmethyltrimethoxysilane, vinylbenzylaminotrimethoxysilane, (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, aminopropyltriphenoxysilane, aminopropyltriphenzoxysilane, aminopropyltrifurfuryloxysilane, aminopropyltris (o-chlorophenoxy) silane, aminopropyltris (p-chlorophenoxy) silane, aminopropyltris (tetrahydrofurfuryloxy) silane, ureidosilane, gamma-methyl-ethyl-trimethoxysilane, gamma-methyl-propyl-tri (o-chlorophenoxy) silane, n-butyl-ethyl-trimethoxysilane, n-butyl-ethyl, Mercaptoethyltriethoxysilane, and vinyltrichlorosilane, methacryloxypropyltris (2-methoxyethoxy) silane.

Other representative silane coupling agents include oligomeric aminoalkylsilanes whose base resin reactive groups are two or more repeating linked aminoalkyl or alkylamino groups. An example of such an oligomeric aminoalkylsilane is Silane All06 solution, available under the trademark Silquest (GE Silicones-OSI specialties, Wilton, CT, USA), which is believed to have the general formula (NH)₂CH₂CH₂CH₂SiO_1.5)_nWherein n is 1 to about 3. Modified aminosilanes, such as a triaminosilane solution (e.g., SilaneAll28, available from approved vendors under the same trademark) may also be used.

Other representative silane coupling agents are ureido-substituted and amino-substituted silanes, as described above. These are, in particular, ureidopropyltrimethoxysilane, ureidopropyltriethoxysilane, aminopropyltrimethoxysilane and aminopropyltriethoxysilane.

Polysiloxanes and polysiloxane derivatives may be used as coupling agents as described above to improve the properties of the modified base resin in solid/liquid separation. Polysiloxane derivatives include those which are obtainable by mixing an organic resin and a polysiloxane resin to incorporate therein various functional groups including urethane, acrylate, epoxy, vinyl and alkyl functional groups.

Silica and/or silicates may also be used in combination with the modified resins of the invention (e.g., added as a mixed component) to potentially increase their affinity for gangue contaminants or desirable materials (e.g., kaolin), particularly siliceous materials, including sand and clay. Other agents that may be used to improve the performance of the modified resin in the separation process of the present invention include polysaccharides, polyvinyl alcohol, polyacrylamide, and known flocculants (e.g., alginates). These agents may also be used with modified urea-formaldehyde resins, as described above, in which 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, such agents may also be used with modified resins that are further modified with anionic functional groups (e.g., sulfonate groups) or stabilized by reaction with an alcohol (e.g., methanol) as described below.

Silica in the form of an aqueous silica sol, for example, is available from akzo nobel under the registered trademark "Bindzil" or from DuPont under the registered trademark "Ludox". Other grades of sols having various silica gel particle sizes and containing various stabilizers may also be obtained. The sol may be stabilized with a base, such as sodium, potassium or lithium hydroxide or quaternary ammonium hydroxide, or a water-soluble organic amine, such as an alkanolamine.

In the preparation of the modified resin, silicates such as alkali metal silicates and alkaline earth metal silicates (e.g., lithium silicate, sodium silicate, potassium silicate, magnesium silicate and calcium silicate) and ammonium silicate or quaternary ammonium silicate may also be used. In addition, stable colloidal silica-silicate blends or mixtures as described in U.S. patent 4,902,442 are also useful.

Particularly advantageous effects are found when the modified resin is prepared using a coupling agent in an amount of from about 0.01 wt.% to about 5 wt.% of a solution or dispersion of the base resin having a solids content of from about 30% to 90%, typically from about 45% to about 70%, in the separation process of the present invention. In general, the addition of smaller amounts of coupling agent does not achieve significant modification of the base resin, while larger amounts do not increase performance enough to offset the increased cost of the coupling agent. When a mixture of coupling agents is used, the total weight of the mixture is generally within this range. A particularly suitable amount of coupling agent is about 0.1 wt.% to about 2.5 wt.% of the base resin solution or dispersion having a solids content in the above-mentioned range.

Alternatively, the coupling agent is generally used in an amount of from about 0.01% to about 17%, typically from about 0.1% to about 8.3% by weight of the solids of the base resin, regardless of the solids content of the base resin solution or dispersion. These representative ranges of added coupling agent based on the weight of the base resin itself apply not only to the resin solution or dispersion, but also to the modified base resin in "neat" form with little or no added solvent or dispersant (e.g., water). These ranges are also generally applicable when the basis as previously described is the total weight of the amine and aldehyde that are reacted with each other to form the base resin. Typically, at least about 90 wt.%, typically at least about 95 wt.% of these amine and aldehyde components are reacted to reduce the amount of free unreacted amine and aldehyde components, which are thus more effectively utilized in the preparation of the base resin polymer, as well as to minimize the deleterious effects (e.g., evaporation into the environment) associated with these free components. As previously mentioned, the modified resin may also be prepared by adding a coupling agent to the reaction mixture of the amine and aldehyde used to form the base resin. The optimum amount of coupling agent depends on many factors including the base resin solids content, the type of base resin and the particular coupling agent, the purity of the raw ore slurry to be beneficiated or the liquid dispersion to be purified, and the like.

The amine-aldehyde resins used in the separation process of the present invention typically comprise from about 40% to about 100% resin solids or non-volatiles, typically from 55% to 75% non-volatiles. The non-volatile content is measured in terms of weight loss by heating a small sample (e.g., 1-5 grams) of the composition at about 105 ℃ for about 3 hours. When a modified resin is used in a substantially "neat" form with little or no volatile components, the neat resin (e.g., as a viscous liquid, gel, or solid form such as a powder) can be added to the froth flotation slurry or liquid dispersion to be purified to form an aqueous resin solution or dispersion in situ. The modified amine-aldehyde resins can be obtained in pure form from solutions or dispersions of these resins using conventional drying techniques such as spray drying.

The aqueous solution or dispersion of the modified resin of the present invention will generally be a clear liquid or a liquid having a white or yellow appearance. They will generally 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 and the free urea content in the urea-formaldehyde resin are typically less than 5% each, typically less than 3% each, and often less than 1% each. Low levels of formaldehyde are typically obtained due to health concerns associated with exposure to formaldehyde volatilization. If desired, conventional "formaldehyde collectors" known to react with free formaldehyde may be added to reduce the formaldehyde level in the solution. However, small amounts of free urea are also desirable for different reasons. Without being limited by theory, because free formaldehyde itself can be modified by coupling agents (e.g., it can react with substituted silanes to increase its affinity for siliceous materials), it is not believed that free urea has the requisite molecular weight, (1) in froth flotation separations, "induced" gangue impurities or desirable materials (e.g., clays) interact with rising gas bubbles, (2) in the purification of liquid dispersions, sufficient amounts of solid impurities to agglomerate into floes, or (3) in the removal of ionic species from aqueous solutions, these species are combined with molecules of sufficiently large size to be retained by filtration. In particular, it has been found that resin polymers having a number average molecular weight greater than about 300 grams/mole exhibit the mass required to facilitate effective separation.

Froth flotation

Due to its high selectivity, the modified resin of the present invention provides good results in terms of saving of added amounts when used as a depressant in froth flotation separations. For example, when used as an inhibitor for beneficiation, the modifying resin is added in an amount of about 100 to about 1000 grams, and typically from about 400 to about 600 grams, based on the weight of the resin solution or dispersion, per metric ton of material (e.g., clay-containing ore) to be cleaned by froth flotation. In general, the optimum amount added for a particular separation can be readily determined by one skilled in the art, depending on a number of factors, including the type and amount of impurities.

The modified resins of the invention can be used for froth flotation of a wide range of useful 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, clays, coal and silver or high molecular weight hydrocarbons such as bitumen). Typically, the raw material to be cleaned and recovered comprises sand or clay, for which the modified resin inhibitor described herein is particularly selective.

Although clay is often considered an impurity in conventional metal or mineral ore beneficiation, it may also be present in relatively large amounts as a major component to be recovered. Some clays, such as kaolin, are valuable minerals in some applications, such as mineral fillers in paper making and rubber manufacturing. Thus, one froth flotation process that may use the modified resin of the present invention includes separating clay from clay-containing ore. The impurities in such ores are generally metals and their oxides, such as iron oxide and titanium dioxide, which are preferentially floated by froth flotation. Other impurities of clay-containing ores include coal. Impurities originally present in most Georgia kaolins that are preferentially floated in the purification process of the present invention include iron-containing titanium dioxide (iron-bearing titanium) and other minerals that are also typically iron-containing, such as mica, ilmenite or tourmaline.

Thus, the clay selectively bound to the amine-aldehyde resin of the present invention can be separated and recovered from metals, metal oxides and coal. In the purification of clays, it is often advantageous to use an anionic trapping agent, such as oleic acid; flocculants such as polyacrylamide, clay dispersants such as fatty or rosin acids and/or rosin oils are used in combination with the modified resins of the present invention as inhibitors to control foaming.

Other representative froth flotation processes of the present invention include the beneficiation of phosphate or potash, as well as the aforementioned other useful metals and minerals, where the removal of siliceous gangue materials and other impurities is an important factor in achieving good process economics. Potassium ores, for example, typically contain a mixture of minerals other than potassium salt (KCl), which is desirable to recover in a foam concentrate. These include halite (NaCl), clay and water-insoluble carbonate minerals such as aluminium silicate, calcite, dolomite and anhydrite.

A process, particularly in the refining of clay-containing ores, comprising further modifying the base resin with anionic functional groups is described in more detail below.

The modified resins of the present invention are also advantageously used for separating bitumen from sand and/or clay co-extracted from natural oil sands deposits. Bitumen/sand mixtures removed from oil sands or bitumen sand reservoirs within hundreds of feet of the surface are typically first mixed with warm or hot water to form an aqueous slurry of oil sands having a reduced viscosity for ease of transport (e.g., by pipeline) into a processing facility. Steam and/or caustic solution may also be injected to condition the slurry for froth flotation, as well as many other clarification steps described below. Aeration of a bitumen-containing slurry comprising sand and clay results in selective flotation of the bitumen, allowing the bitumen to be recovered as a purified product. This aeration may be achieved by merely agitating the slurry to release 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 solid impurities is readily determined by one skilled in the art.

Thus, the use of the modified resin depressant of the present invention advantageously facilitates the retention of sand and/or clay impurities in the aqueous portion that are removed from the bottom of the froth flotation vessel. The bottom is enriched (i.e., has a higher concentration) with respect to the original bitumen slurry with sand and/or clay impurities. The total purification of bitumen may rely on two or more flotation separation stages. For example, the intermediate section of the primary flotation separation vessel may contain a large amount of bitumen, which can ultimately be recovered in the secondary flotation of this "intermediate" section.

Generally, in any froth flotation process according to the invention, at least 70% of the useful material (e.g. bitumen or kaolin) is recovered from the raw material (e.g. clay-containing ore) with a purity of at least 85 wt.%. Further, when the modified resin of the present invention is used as an inhibitor, it may be used in combination with a conventionally known trapping agent. These collectors include, for example, fatty acids (e.g., oleic acid, sodium oleate, hydrocarbon oils), amines (e.g., dodecylamine, octadecylamine, α -aminoarylphosphonic acid, and sodium sarcosinate), and xanthan salts. Likewise, conventional inhibitors known in the art can also be combined with the modified resin inhibitor. Conventional inhibitors include guar gum and other hydrocolloid polysaccharides, sodium hexametaphosphate and the like. Conventional frothers that aid in trapping (e.g., methyl isobutyl carbinol, pine oil, and polypropylene oxide) may also be used in conjunction with the modified resin depressant of the present invention, depending on normal flotation operations.

As will be appreciated by those skilled in the art, the pH of the slurry to which the modified resin of the present invention is added as an inhibitor in froth flotation separation will vary depending on the particular material being treated. Typically, the pH varies from neutral (pH 7) to strongly alkaline (e.g., pH 12). It is believed that in some flotation systems, such as copper sulfide flotation, high pH values (e.g., about 8 to about 12.5) produce the best results.

In froth flotation, which is generally used for the beneficiation of solid materials (e.g. minerals or ores), the raw ore to be beneficiated is usually first ground to a "disengaging mesh" size, where the majority of the particles containing the useful material are separated mineral or metal particles or salt crystals, in which particles gangue (e.g. clay and/or sand) is mixed. The solid material may be ground to produce, for example, particles having an average diameter of one-eighth inch, prior to combining the material into a brine solution to produce an aqueous slurry. After the material is comminuted and slurried, the slurry can be stirred or agitated in a "washing" process to break down the clay into very fine particles that remain as a cloudy suspension in the brine. Some of these clays can be washed off the ore particles prior to froth flotation as an aqueous clay-containing suspension or brine. Furthermore, any conventional pre-treatment steps including further comminution/screening, cyclone separation and/or water splitting steps may also be used to further size reduce/classify the raw material, remove the brine of clay, and/or recover smaller solid particles from the cloudy brine, respectively, prior to froth flotation, as is known in the art.

The modified resin of the present invention used as a depressant is typically added to the aqueous slurry before or during froth flotation in such a way that the depressant is readily dispersed throughout. As mentioned above, conventional collectors can be used to aid in the flotation of the desired useful material. In a froth flotation process, a slurry, typically having a solids content of about 10 to 50 wt.%, is passed to one or more flotation cells. Air is passed into the bottom of these tanks and the relatively hydrophobic portion of the material having a selective affinity for the rising bubbles floats to the surface (i.e., the froth), where it is skimmed off and recovered. A bottom product that is hydrophilic with respect to the foam concentrate may also be recovered. The process may be accompanied by stirring. Commercially acceptable products can often be produced from the separated fractions recovered in this manner, often after using further conventional steps including separation (e.g. by centrifugation), drying (e.g. in a gas kiln), size classification (e.g. screening) and refining (e.g. crystallization).

Although not always the case, froth flotation according to the present invention may include flotation in a "rougher cell" and then one or more "refinements" of the roughed concentrate. Two or more flotation steps may also be employed, first recovering a large amount of useful material comprising more than one component, followed by selective flotation to separate the components. The modified resins of the present invention, when used as depressants, can be advantageously used in any of these steps to enhance the selective recovery of the desired material via froth flotation. When multi-stage froth flotation is used, the modified resins may be added at once prior to multi-stage flotation, or they may be added separately at each flotation stage. Other separations

Due to their affinity for solid impurities in suspension, the modified resins of the present invention are useful in a wide variety of separations, particularly those applications involving the removal of siliceous impurities (such as sand and/or clay) from aqueous suspensions or slurries of such impurities. These aqueous suspensions or slurries can thus be treated with the modified resins of the present invention to allow at least a portion of the impurities to be separated from the purified liquid in an impurity-enriched fraction. An "impurity-enriched" fraction refers to a fraction of a suspension or slurry that is enriched in solid impurities (i.e., contains a higher percentage of solid impurities than the solid impurities originally present in the suspension or slurry). Conversely, the purified liquid contains a lower percentage of solid impurities than the solid impurities originally present in the liquid suspension or slurry.

The separation process described herein is applicable to "suspensions" as well as "slurries" of solid particles. These terms are sometimes synonymous, but in the case of "slurry" there is sometimes a distinction based on the addition of at least some agitation or energy to maintain homogeneity. Because the process of the invention described herein is broadly applicable to the separation of solid particles from an aqueous medium, the term "suspension" is used interchangeably with "slurry" (and vice versa) in the description of the invention and in the appended claims.

The treating step may include adding a sufficient amount of the modified resin to cause charge interaction and to cause agglomeration or flocculation of the solid impurities into larger agglomerates. One skilled in the art will readily recognize that the necessary amount can be readily determined based on a number of variables, such as the type and concentration of impurities. In other embodiments, the treating may comprise continuously contacting the suspension with a fixed bed of the solid modified resin.

During or after treatment of the suspension with the modified resin, agglomerated or flocculated solid impurities (which may now be in the form of larger agglomerated particles or flocs, for example) are removed. Removal can be achieved by flotation (with or without the use of ascending bubbles, as described above in connection with froth flotation) or sedimentation. The optimal method of removal depends on the relative density of the floe or other factors. Increasing the amount of modified resin used to treat the suspension also increases the tendency of the floe to float rather than settle in some cases. Filtration or straining can also be an effective means of removing the solid particles agglomerated floc, whether they are at the surface or in the sediment.

Examples of suspensions that may be purified in accordance with the present invention include drilling fluids of oil and gas wells that accumulate rock (or drill cuttings) solids during normal use. These drilling fluids (often referred to as "drilling mud") are important in the drilling process for several reasons, including the transport of these drill cuttings from the drilling zone to the surface, the removal of which allows the drilling mud to be recycled. The modified resins of the present invention are added to oil well drilling fluids, particularly water-based (i.e., aqueous) drilling fluids, to effectively agglomerate or flocculate solid particle impurities into larger clumps (or flocs) and thereby facilitate their separation by settling or flotation. The modified resins of the present invention may be used in combination with known flocculants such as polyacrylamide or hydrocolloid polysaccharides for this application. Typically, in the case of water-based oil or gas well drilling fluids, the separation of solid impurities is sufficient to provide a purified drilling fluid for reuse in drilling operations.

Other aqueous suspensions of practical interest include aqueous suspensions or brines containing clay associated with ore refining processes including those described above. For example, the production of purified phosphate from mined calcium phosphate rock typically relies on multiple separations of solid particulates from an aqueous medium, whereby such separations can be improved with the modified resins of the present invention. Calcium phosphate is produced from an average depth of about 25 feet underground throughout the process. Phosphate rock is initially recovered in mother rock containing sand and clay impurities. The parent rock is first mixed with water to form a slurry, which is screened to retain the phosphate gravel and to allow the fine clay particles to pass with large amounts of water as a clay slurry effluent, typically after mechanical agitation.

These clay-containing effluents generally have higher flow rates and typically carry less than 10 wt.% solids, and more typically contain only about 1 wt.% to 5 wt.% solids. However, the dehydration of such waste clays for water recycling (e.g., by settling or filtration) presents significant challenges for recovery. However, the treatment of the clay slurry effluent obtained in the production of phosphate with the modified resin of the present invention can reduce the time required for dehydration. The reduction in clay settling time allows for the efficient reuse of purified water from clay dehydration in phosphate production operations. In one embodiment of the purification process, wherein the suspension is a clay-containing discharge slurry from a phosphate production plant, the purified liquid contains less than about 1 wt.% solids after a settling or dewatering time of less than about 1 month.

In addition to the phosphate gravel and clay slurry discharge retained by screening described above, a mixture of sand and finer phosphate particles is also obtained in the initial treatment of the mined phosphate matrix. The sand and phosphate in this fluid are separated by froth flotation, which can be improved by using the modified resin of the present invention as a sand depressant as described above.

Another application of the resin in the slurry dewatering zone is the filtration of coal from an aqueous slurry. Dewatering of coal is industrially important because as the water content increases, the BTU value decreases and thus the quality of the coal decreases. Thus, in one embodiment of the invention, the aqueous coal-containing suspension or slurry is treated with a modifying resin prior to dewatering the coal by filtration.

Another important application of the modified resins of the invention is in the field of sewage treatment, which refers to various processes responsible for the removal of impurities from industrial and municipal wastewater. Sewage is purified by such processes, providing purified water suitable for discharge into the environment (e.g., rivers, streams, and oceans), as well as sludge. Sewage refers to any type of aqueous waste that is typically collected in a sewer system and then transported to a treatment facility. Thus, sewage includes municipal wastewater from toilets (sometimes referred to as "foul waste") and basins, bathrooms, showers, and kitchens (sometimes referred to as "foul sewage"). Sewage also includes industrial and commercial waste water (sometimes referred to as "industrial waste water") as well as storm water streams from hard surface areas such as roofs and streets.

Conventional treatment of wastewater often involves primary, primary and secondary treatment steps. Primary treatment refers to the filtration or screening of large solids such as wood, paper, debris, etc. and grit that often damage the pump. The majority of the remaining solids are then separated by settling in large water tanks with subsequent primary treatment, and the solids-enriched sludge is recovered from the bottom of these tanks and further processed. The purified water is also recovered and typically subjected to secondary treatment via biological processes.

Thus, in one embodiment of the present invention, the settling or precipitation of the wastewater may comprise treating the wastewater with the modified resin of the present invention. This treatment may be used to improve settling operations (batch or continuous), for example by reducing the residence time required to achieve a given operation (e.g., based on the purity of the purified water and/or the percent recovery of solids in the sludge). In addition, the improvement in producing a higher purity of purified water and/or higher recovery of solids in the sludge is evident for a given settling time.

After sewage is treated by the modified resin and purified water flow is removed by precipitation, the modified resin can be used or introduced into a secondary treatment process to further purify water. Secondary treatment generally relies on the action of naturally occurring microorganisms to break down organic material. In particular, aerobic biological processes substantially degrade the biological content of the purified water recovered from the primary treatment. Microorganisms (e.g., bacteria and protozoa) consume soluble organic impurities (e.g., sugars, fats, and other organic molecules) that are biodegradable and bind many of the hardly soluble fractions into floes, thereby further facilitating the removal of organic materials.

Secondary treatment relies on "supplying" oxygen and other nutrients to the aerobic microorganisms, allowing them to survive and consume organic impurities. Advantageously, the nitrogen-containing modified resins of the present invention can serve as a "food" source for microorganisms in the secondary treatment, and possibly as an additional flocculant for organic materials. Thus, in one embodiment of the invention, the method of wastewater purification further comprises, after removing the purified water by sedimentation (in the primary treatment step), further treating the purified water in the presence of microorganisms and a modified resin, optionally with an additional amount of modified resin to reduce the Biochemical Oxygen Demand (BOD) of the purified water. As is understood in the art, BOD is an important indicator of water quality and represents the mg/l (or ppm by weight) of oxygen required by microorganisms to oxidize organic impurities within 5 days. The BOD of the purified water after treatment with the microorganisms and the modified resin is generally less than 10ppm, typically less than 5ppm, and often less than 1 ppm.

The modified resin of the invention can also be applied to the purification of waste water of pulp mills and paper mills. These aqueous waste streams typically contain solid impurities in the form of fibrous material (e.g., waste paper, bark, or other wood constituents, such as wood chips, wood strands, wood fibers, or wood particles; or plant fibers, such as wheat straw fiber, rice fiber, switchgrass fiber, soybean straw fiber, bagasse fiber, or corn straw fiber; and mixtures of such impurities). According to the process of the present invention, an effluent stream comprising cellulosic solid impurities is treated with the modified resin of the present invention to remove purified water via sedimentation, flotation or filtration.

Separation of bitumen from sand and/or clay impurities as described above, various separation steps may be employed 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 with the modified resin of the present invention, followed by removal of a portion of the sand and/or clay impurities in an impurity-enriched fraction (e.g., bottom), or removal of a clarified bitumen fraction. As noted above, in connection with phosphate ore treatment wastewater, which typically includes solid clay particles, the treatment step may include flocculating these impurities to facilitate their removal (e.g., by filtration). The wastewater effluents from bitumen treatment facilities likewise contain sand and/or clay impurities and therefore benefit from treatment with the modified resins of the present invention to dewater them and/or to remove at least a portion of these solid impurities in an impurity-enriched fraction. A particular process fluid of interest produced during bitumen extraction, known as "mature fine tailings," is an aqueous suspension of fine solid particles that can benefit from dewatering. Typically, in the case of sand-and/or clay-containing suspensions from bitumen production facilities, the separation of solid impurities is sufficient to enable the recovery or removal of a purge liquid or water stream that can be recycled to the bitumen process.

The treatment of various intermediate fluids and effluents with the modified resins of the present invention in bitumen production processes 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 recognized by those skilled in the art, other techniques for bitumen purification, such as centrifugation through a "Syncrude Process", will produce an aqueous intermediate fluid from which it is desirable to remove solid impurities, as well as a by-product fluid.

The modified resins of the invention can be used to remove suspended solid particles such as sand and clay in the purification of water, particularly in order to make it potable.

Moreover, the modified resins of the present invention additionally have the property of complexing metal cations (e.g., lead and mercury cations) so that these unwanted impurities are removed simultaneously with the solid particles. Therefore, the modified resin of the present invention can be used for effectively treating impure water containing solid particle impurities and metal cation impurities. Without being bound by theory, it is believed that negatively charged moieties, such as the carbonyl oxygen atoms on the urea-formaldehyde polymer backbone, complex with the unwanted cations, facilitating their removal. Typically, such complexation occurs in water having a pH greater than about 5, which typically ranges from about 7 to about 9.

Another possible mechanism for metal cation removal is based on its binding to negatively charged solid particles. Flocculation and removal of these particles will also result in removal of metal cations, at least to some extent. Regardless of the mechanism, in one embodiment, the treatment and removal of these impurities can be accomplished in accordance with the present invention to produce potable water.

The removal of metal cations may represent the primary or even the only means of water purification achieved by the modified resin, for example when the purified water contains little or no solid particles. The modified resin may be used in solid form in a continuous process whereby impure water containing metal cations is continuously passed through a fixed bed of the resin. Alternatively, the modified resin, which is typically in a dissolved form with a lower molecular weight, may be added to the impure water to treat it. The complex cation in this example can be removed by ultrafiltration through, for example, a porous membrane (e.g., polysulfone) having a molecular weight cut-off less than the molecular weight of the modified resin. The water purification methods described herein may also be used in conjunction with known methods including reverse osmosis, UV irradiation, and the like.

To increase the efficiency of the complexation of the modified resin with metal cations, it may be desirable to further modify the base resin with one or more anionic functional groups. Such modifications are well known in the art and may include the reaction of the base or modified resin to introduce the desired functional group (e.g., by sulfonation with sodium metabisulfite). Alternatively, further modification may be effected during the preparation of the base resin (e.g. during condensation) by the addition of an anionic comonomer (e.g. sodium acrylate) to the base resin or to the cross-linking agent. For example, as described above, the organopolysiloxane derivative used as the coupling agent can be prepared by introducing another organic resin functional group (e.g., acrylate) into the coupling agent. Representative other functional groups that can be used to modify the base resin or modified resin (including urea-formaldehyde resins) include anionic functional groups, bisulfite, acrylate, acetate, carbonate, azide, amido, and the like. The process of modifying the base resin with other functional groups is well known to those skilled in the art. The introduction of anionic functional groups into the base resin may also be accomplished in separations involving the clarification of slurries containing solid clay particles (e.g., by froth flotation, flocculation, etc.) (including those described above, e.g., in the clarification of kaolin ores). Without being limited by theory, the sulfonation of the base resin or the introduction of other anionic functional groups may also enhance hydrogen bonding between the base resin and the surrounding aqueous phase to inhibit condensation of the base resin or otherwise enhance its stability.

Thus, as noted above, in one embodiment, the invention is a method of purifying water containing metal cations by treating the water with a modified resin as described herein and which may be further modified with anionic groups. Removal of at least a portion of the metal cations may be accomplished by holding it in a fixed bed of modified resin or otherwise filtering it out. In the latter case, removal by filtration (e.g., membrane filtration) can be achieved by direct binding of the metal cations to the modified resin or by indirect binding of the modified resin to solid particles to which the modified resin has affinity. In the case of indirect bonding, as mentioned above, flocculation of solid particles will also necessarily flocculate a portion of the metal ions, and these particles can therefore be removed by flotation or sedimentation.

The modified resins of the present invention can therefore be advantageously used for treating water to remove metal cations such as arsenic, lead, cadmium, copper and mercury, among others, which are known to pose health risks when ingested. These cations thus include As⁵⁺、pb²⁺、Cd²⁺、Cu²⁺、Hg²⁺And mixtures thereof. Typically, the degree of removal achieved is such that the purified water after treatment is substantially free of one or more of the above-mentioned metal cations. By "substantially free" is meant that the concentration of the metal cation or cations of interest is reduced to or below a concentration deemed safe (e.g., as recognized by regulatory agencies, such as the Environmental Protection Agency in the united states). Thus, in various representative embodiments, the purified water will contain up to about 10ppb As5⁺Up to about 15ppb of pb²⁺Up to about 5ppb of Cd²⁺Up to about 1.3ppm Cu²⁺And/or up to about 2ppb of Hg²⁺. I.e. in generalAt least one, usually at least two, and often all of the above anions are at or below these limiting concentrations of purified water.

In any of the applications described herein, the modified resins of the present invention may be stabilized by reaction with an alcohol (i.e., etherification). Without being bound by theory, it is believed that etherification of the pendant alkanol-based functionality inhibits further condensation of the base resin (e.g., condensation of the urea formaldehyde resin itself). This may ultimately hinder or prevent precipitation of the base resin during long term storage, enabling the etherified resin to have a greater molecular weight than its corresponding non-etherified resin without a corresponding loss in its stability.

Etherification thus involves the reaction of amine-aldehyde adducts or condensates or even modified resins as described above with alcohols. In one embodiment, the urea-formaldehyde resin is etherified with an alcohol having 1 to 8 carbon atoms prior to modifying the urea-formaldehyde base resin with the coupling agent. Representative alcohols for etherification include methanol (e.g., for methylation), ethanol, n-propanol, isopropanol, n-butanol, and isobutanol. In an exemplary preparation of the etherified base resin, the amine-aldehyde adduct or condensation reaction product is heated to a temperature of about 70 ℃ to about 120 ℃ in the presence of an alcohol until fully etherified. Acids such as sulfuric acid, phosphoric acid, formic acid, acetic acid, nitric acid, alum, ferric chloride, or other acids may be added before or during the reaction with the alcohol. Sulfuric acid or phosphoric acid is generally used.

All documents cited in this specification, including but not limited to all U.S. patents, international and foreign patents and patent applications, and all abstracts and papers (e.g., journal articles, magazines, etc.) are incorporated herein by reference in their entirety. The discussion of the 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 documents. 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 the above-described theory and/or mode of interaction, 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 intended to limit the scope of the invention thereto, and other equivalent embodiments will become apparent with reference to this specification and the appended claims.

Froth flotation

Example 1

Various urea-formaldehyde resins were prepared as low molecular weight condensation resins, first forming methylolated urea adducts under basic conditions and then forming the condensates under acidic conditions. The condensation reaction is stopped by raising the pH of the condensation reaction mixture. Other preparation conditions were as described above. The corresponding molecular weights in grams/mole (mol. wt.) of these base resins are listed in table 1 below, along with the approximate normalized weight percent of free urea, cyclic urea moieties (cyclic urea), Mono-methylolated urea (Mono), and bound bis/tris-methylolated urea (Di/Tri). In each example, the base resin is in solution with a resin solids content of 45-70%, a viscosity of 500cps or less, and a free formaldehyde content of less than 5 wt.%.

TABLE 1 Urea-formaldehyde base resin

ID Mol.Wt.^a Free urea Cyclic ureas Mono Di/Tri

Resin A4068393023

Resin B^* 997 5 50 22 23

Resin C and C'^** 500 6 46 25 23

Resins D and D'^*** 131 4 32 13 06

Resin E5780181072

Resin F11581441144

Resin G619026371

^*Resin B is a very stable urea-formaldehyde resin with a high cyclic urea content. This resin is described in us patent 6,114,491.

^**Resin C' was formed by adding 2 wt.% diethylenetriamine and 2 wt.% dicyanodiamide to a urea and formaldehyde mixture during resin preparation, in addition to silane #1 (described below).

^***Resin D' was formed by adding 0.75 wt.% cyclic phosphate to a mixture of urea and formaldehyde during the resin preparation. The resin has a lower molecular weight, has a high content of free urea, is substantially free of free formaldehyde, and has a higher content of non-volatiles (about 70% solids).

^aUsing with appropriate rulerInch PLgel^TMGel Permeation Chromatography (GPC) of the column (polymer laboratories, inc., Amherst, MA, USA) determined the number average molecular weight, using 0.5% glacial acetic acid/tetrahydrofuran as mobile phase at 1500psi, and polystyrene, phenol, and bisphenol-a as measurement standards.

The urea resin solution as described above is modified with a silane coupling agent to prepare the resin inhibitor of the present invention. The silane coupling agents #1, #2, and #3 used in the preparation of these modified resins were all substituted silanes as defined in table 2 below.

TABLE 2 silane coupling Agents

ID Type (B) Source

Silane # 1-Ylpropyltrimethoxysilane Silane A1160^↑

Silane #2 oligomeric Aminoalkylsilane Silane A1106^↑

Silane #3 aminopropyltriethoxysilane Silane A1100^↑

^↑Available under the trademark Silquest (GE Silicones-OSi Specialties, Wilton, CT, USA)

Example 2

The above urea-formaldehyde base resin described in table 1 was modified with silane coupling agents #1, #2 and #3 described in table 2 in accordance with the foregoing procedure. Namely: after the low molecular weight condensate is formed as described above and the alkali is added to raise the pH of the solution and terminate the condensation reaction, the silane coupling agent is added to the base resin solution in an amount of about 0.1 to 2.5% by weight of the resin solution. And then heating the basic mixture of the base resin and the silane coupling agent to a temperature of about 35 to 45 ℃ for about 0.5 to 4 hours until a viscosity of about 350 to 450cps is reached.

Example 3

Various urea-formaldehyde resins representing either the unmodified resin or the resin modified with a silane coupling agent as described above, as well as the control inhibitor, were tested for selectivity in laboratory size beneficiation studies to remove siliceous sand and clay impurities from potash ores by froth flotation. In each test, the amount of inhibitor used per unit weight of ore to be beneficiated, the solids content of the ore slurry, the pH of the slurry, the air flow rate per unit volume of slurry, the phosphate purity of the ore prior to beneficiation, and various conditions all represent industrial operations. In each test, the ore recovered by flotation was at least 90 wt.% pure phosphate material. Commercially available guar gum was used as an inhibitor control sample.

In these tests, the performance of each depressant was determined according to the amount of potash that could be recovered (i.e. floated) at a particular purity. This amount provides selectivity of each inhibitor in binding to the undesirable gangue materials. In other words, the higher the selectivity of the depressants, the greater the amount of 90% pure phosphate that can be floated. The following data were obtained as shown in table 3 below.

TABLE 3 Performance of inhibitors in phosphate recovery

Inhibitors Of flotation>Grams of 90% potassium

Control 1-guar gum 212

Resin A. modification with silane #1 230

Resin A. unmodified 85

Resin B, 226 modification with silane #1

Resin B. unmodified 97

Resin C. modification 172 with silane #1

Resin C' modification 158 with silane #1

Resin D, modification with silane #1 82 (average of 2 tests)

Resin D'. unmodified 100

Resin E. modification with silane #1 215

Resin E, 232 modified with silane #2 (average of 2 tests)

Resin E, 226 modified with silane #3 (average of 2 tests)

Resin F. modification 229 with silane #1

Resin F. 231 modified with silane #2

Resin F. 225 modification with silane #3

Resin G modified 223 with silane #1

Resin G modified 228 with silane #2

Resin G modified 224 with silane #3

Based on the above results, modifying the urea-formaldehyde base resin (preferably by covalent bonding) with a silane coupling agent can significantly improve the performance of the resin as an inhibitor in froth flotation. Moreover, as the molecular weight of the base resin increases, the performance advantages associated with the use of silane coupling agents become more and more pronounced. In particular, base resins having a molecular weight above about 300 g/mole before modification give good properties. This is shown in FIG. 1, which shows a comparison of the properties of the silane coupling agent modified resins, which have molecular weights of about 400 to about 1200 g/mol, with the unmodified resins. Furthermore, urea-formaldehyde resins within this molecular weight range are not affected by the use of other resin modifiers of the base resin (e.g., diethylenetriamine, dicyanodiamide, phosphate esters, etc.).

Figure 1 also shows that silane coupling agent modified resins having molecular weights of about 400 to about 1200 grams/mole perform better than their unmodified counterparts, generally better than guar gum known in the art for binding clays and talc, but which is significantly more expensive. Furthermore, the inhibitors of the present invention show much higher selectivity for flotation of crude phosphate particles compared to guar gum. The amount of fine particles in the clarified phosphate obtained by flotation in the guar gum test is relatively large, which significantly increases the costs associated with downstream drying and screening operations to produce a marketable product.

Example 4

The performance of the modified resin inhibitor sample of the present invention in a potash beneficiation plant is compared to the properties of guar gum currently used as a commercial inhibitor of gangue materials in that plant. The inhibitor of the present invention used in this test was resin F described in examples 1-3 above, modified with silane # 2.

For comparative testing, the amount of inhibitor used per unit weight of ore to be floated, the solids content of the ore slurry, the pH of the slurry, the air flow rate per unit volume of slurry, the phosphate purity of the ore prior to beneficiation, and other conditions all represent industrial operations. The performance of each depressant was determined based on the amount of potash that could be recovered (i.e., floated) at a particular purity. This amount provides selectivity of each inhibitor in binding to the undesirable gangue materials. In other words, the higher the selectivity of the depressants, the greater the amount of potash that can be floated at a particular purity.

Compared with guar gum, the inhibitor of the invention improves the yield of purified potash by about 19%. In addition, the yield of the coarse particles of the desired potash (potassium chloride) mineral is substantially increased using the urea resin modified with the silane coupling agent. This increase in the yield of crude material reduces the costs associated with the energy requirements for drying and the overall processing time required for further refining prior to sale, for the reasons described above.

Example 5

The silane coupling agent modified urea-formaldehyde (UF) resin as described above was tested for its ability to reduce the dewatering time of various solid impurities suspended in an aqueous slurry by filtration. In each test, a sample of 25 grams of solid impurities was mixed with 100 grams of 0.01 mole KNO₃And (4) uniformly mixing to form slurry. The pH of the slurry was measured. The slurry was then vacuum filtered using a standard 12.7cm diameter Buchner funnel device and 11.0cm diameter Whatman qualitative #1 filter paper. The dewatering time in each example is the time required to recover 100ml of filtrate through the filter paper.

For each solid impurity tested, a control run was run, followed by the same run except that (1) 0.5-1 grams of silane-modified UF resin was added to the slurry, and (2) the slurry was mixed for an additional minute with stirring after the homogeneous slurry was re-formed. The results are shown in Table 4 below.

TABLE 4 dewatering time of aqueous slurries (25 g solid impurities at 100 g 0.01M KNO₃Middle)

Solid contrast control plus 0.5-1 g of silane modified UF resin

Geltone^*13.1 second 8.2

(pH value of slurry) (8.1) (8.5)

Bentonite 5.32.3

(pH value of slurry) (8.8)

Graphite 8.15.2

(pH value of slurry) (4.4) (4.5)

Kaolin 10.55.4

(pH value of slurry) (3.3) (3.7)

Talc (<10 microns) 2.01.3

(pH value of slurry) (8.8) (8.9)

^*Trade name of montmorillonite clay

The above results show that silane modified UF resins, even when used in small amounts, still have the ability to significantly reduce the dewatering time for many solid particles.

Claims (44)

1. A method of purifying clay from a clay-containing ore, the method comprising:

providing a clay-containing ore comprising clay and one or more organic or inorganic impurities;

contacting the aqueous slurry of the clay-containing ore with an inhibitor comprising an amine-aldehyde resin and a silane coupling agent;

wherein the amine-aldehyde resin is a base resin that is the reaction product of a primary or secondary amine and an aldehyde; and

wherein the base resin is modified with a silane coupling agent; and

the purified clay is separated from the clay-containing ore by froth flotation of at least one impurity.

2. The method of claim 1, wherein the one or more organic or inorganic impurities are selected from metals, metal oxides, minerals, coal, bitumen, or any combination thereof.

3. The method of claim 1, wherein the clay-containing ore comprises kaolin clay, wherein the one or more organic or inorganic impurities are selected from iron oxide, titanium dioxide, or a combination thereof.

4. A method of purifying bitumen comprising:

contacting an aqueous slurry comprising bitumen and one or more impurities with an inhibitor comprising an amine-aldehyde resin and a silane coupling agent;

wherein the amine-aldehyde resin is a base resin that is the reaction product of a primary or secondary amine and an aldehyde; and

wherein the base resin is modified with a silane coupling agent; and

separating bitumen from the aqueous slurry by froth flotation,

wherein the foam comprises a lower concentration of at least one or more impurities relative to the aqueous slurry.

5. The method of claim 4, wherein the one or more soluble or insoluble impurities comprise sand or clay.

6. A method of purifying water comprising:

providing an aqueous composition comprising water and one or more impurities;

contacting the aqueous composition with an inhibitor comprising an amine-aldehyde resin and a silane coupling agent to form a resin-impurity complex;

wherein the amine-aldehyde resin is a base resin that is the reaction product of a primary or secondary amine and an aldehyde; and

wherein the base resin is modified with a silane coupling agent; and

separating the resin-impurity complex from the aqueous composition to provide purified water.

7. The method of claim 6, wherein the separating step c) comprises settling, flotation, filtration, or any combination thereof.

8. The method of claim 7, wherein the filtration is membrane filtration.

9. The method of claim 6, wherein the one or more soluble or insoluble impurities are selected from As⁵⁺、Pb²⁺、Cd²⁺、Cu²⁺、Mn²⁺、Hg²⁺Or any combination thereof.

10. The method of claim 6, wherein the aqueous composition comprising one or more soluble or insoluble impurities is a water-based oil well drilling fluid, a clay-containing discharge slurry from a phosphate production plant, a coal-containing suspension, sewage, pulp or paper mill effluent, an intermediate product of an asphalt production process, or a sand or clay-containing discharge slurry of an asphalt production process.

11. The method of claim 6, wherein separating the resin-impurity complex from the aqueous composition comprises removing purified water for reuse in phosphate production.

12. The method of claim 6, wherein the method further comprises step d): treating the purified water in the presence of microorganisms and an amine-aldehyde resin to reduce the biochemical oxygen demand of the purified water.

13. The method of claim 6, wherein the aqueous composition is a water-based oil well drilling fluid, and wherein separating the resin-impurity complex from the aqueous composition comprises removing the purified drilling fluid for reuse in oil well drilling.

14. The method of claim 6, wherein the aqueous composition is a coal-containing suspension, and wherein separating the resin-impurity complex from the aqueous composition comprises removing a coal-rich fraction by filtration.

15. The method of claim 6, wherein the one or more soluble or insoluble impurities are clay, sand, or a fibrous material.

16. A method of beneficiation of ore, comprising:

providing an ore comprising a valuable mineral and one or more impurities;

contacting an aqueous slurry of the ore with an inhibitor comprising an amine-aldehyde resin and a silane coupling agent;

wherein the amine-aldehyde resin is a base resin that is the reaction product of a primary or secondary amine and an aldehyde; and

wherein the base resin is modified with a silane coupling agent; and

valuable material is separated from the aqueous slurry by froth flotation.

17. The method of claim 16, wherein the valuable material is 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, silver, coal, or any combination thereof.

18. The method of claim 16, wherein the one or more impurities are selected from sand, clay, iron oxide, titanium oxide, iron-containing titanium dioxide, mica, ilmenite, tourmaline, aluminum silicate, calcite, dolomite, anhydrite, or combinations thereof.

19. The method of claim 16, wherein the amine-aldehyde resin is the reaction product of a primary amine and formaldehyde.

20. The method of claim 16, wherein the amine-aldehyde resin comprises a solution or dispersion having a resin solids content of 30 wt.% to 90 wt.%, wherein the silane coupling agent is present in an amount of 0.01 wt.% to 5 wt.% of the amine-aldehyde resin solution or dispersion.

21. The process as claimed in claim 16, wherein the ore slurry is treated with the amine-aldehyde resin in an amount in the range of 100-1000 g of amine-aldehyde resin per ton of ore.

22. The process of claim 16, wherein the process recovers at least 70 wt.% of valuable material from the ore, wherein the purity of valuable material is at least 85 wt.%.

23. The method of claim 16, wherein the amine-aldehyde resin has a solids content of 40% to 100%.

24. The method of claim 16, wherein the amine-aldehyde resin is substantially pure and is a viscous liquid, a colloid, or a solid powder.

25. The method of any of claims 1-18 and 20-24, wherein the amine-aldehyde resin is the reaction product of a primary or secondary amine and an aldehyde, wherein the silane coupling agent is selected from a substituted silane, silica, silicate, polysiloxane, or any combination thereof.

26. The method of any one of claims 1-24, wherein the amine-aldehyde resin comprises a urea-formaldehyde resin, wherein the silane coupling agent comprises a substituted silane.

27. The method of any one of claims 1-24, wherein the amine-aldehyde resin is the reaction product of an aldehyde and an amine in a molar ratio of 1.5: 1 to 4: 1.

28. The method of any of claims 1-24, wherein the amine-aldehyde resin comprises a urea-formaldehyde resin that is a reaction product of formaldehyde and urea in a molar ratio of 1.75: 1 to 3: 1.

29. The method of any one of claims 1-24, wherein the silane coupling agent comprises a ureido substituted silane, an amino substituted silane, a sulfur substituted silane, an epoxy substituted silane, a methacryloyl substituted silane, a vinyl substituted silane, an alkyl substituted silane, a haloalkyl substituted silane, or any combination thereof.

30. The method of any one of claims 1-24, wherein the silane coupling agent is selected from ureidoalkyltrialkoxysilanes, aminoalkyltrialkoxysilanes, oligomeric aminoalkylsilanes, or any combination thereof.

31. The method of any one of claims 1-24, wherein the silane coupling agent is selected from the group consisting of ureidopropyltrimethoxysilane, ureidopropyltriethoxysilane, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminopropylmethyldiethoxysilane, aminopropylmethyldimethoxysilane, aminoethylaminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane, diethylenetriaminopropyltrimethoxysilane, diethylenetriaminopropyltriethoxysilane, diethylenetriaminopropylmethyldimethoxysilane, diethylenetriaminopropylmethyldiethoxysilane, cyclohexylaminopropyltrimethoxysilane, hexamethylenemethyldiethoxysilane, anilinomethyltrimethoxysilane, anilinomethyltriethoxysilane, and mixtures thereof, Diethylaminomethyltriethoxysilane, (diethylaminomethyl) methyldiethoxysilane, methylaminopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, bis (triethoxysilylpropyl) disulfide, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, mercaptopropylmethyldimethoxysilane, 3-thiocyanatopropyltriethoxysilane, isocyanatopropyltriethoxysilane, glycidoxypropyltrimethoxysilane, glycidoxypropyltriethoxysilane, glycidoxypropylmethyldiethoxysilane, glycidoxypropylmethyldimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, methacryloxypropylmethyldimethoxysilane, methacryloxypropyldimethoxysilane, diethylaminomethyldimethoxysilane, diethylaminomethyldiethoxysilane, mercaptomethyldimethoxysilane, mercaptopropyltrimethoxysilane, mercaptomethyldimethoxysilane, mercaptomethyldimeth, Chloropropyltrimethoxysilane, chloropropyltriethoxysilane, chloromethyltriethoxysilane, chloromethyltrimethoxysilane, dichloromethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, vinyltriacetoxysilane, alkylmethyltrimethoxysilane, vinylbenzylaminotrimethoxysilane, (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, aminopropyltriphenoxysilane, aminopropyltrifurfuroxysilane, aminopropyltris (o-chlorophenoxy) silane, aminopropyltris (p-chlorophenoxy) silane, aminopropyltris (tetrahydrofurfuroxy) silane, ureidosilane, mercaptoethyltriethoxysilane, and vinyltrichlorosilane, Methacryloxypropyltris (2-methoxyethoxy) silane, or any combination thereof.

32. The method of any one of claims 1-24, wherein the amine-aldehyde resin further comprises anionic functional groups.

33. The method of any one of claims 1-24, wherein the amine-aldehyde resin has a concentration of free formaldehyde of less than 5%.

34. The method of any one of claims 1-24, wherein the amine-aldehyde resin has a number average molecular weight (Mn) of greater than 300 g/mole.

35. The method of any one of claims 1-24, wherein the treating step further comprises treating with silica, a silicate, a polysiloxane, a polysaccharide, polyvinyl alcohol, polyacrylamide, a flocculant, or any combination thereof.

36. An inhibitor comprising an amine-aldehyde resin and a silane coupling agent,

wherein the amine-aldehyde resin is a base resin that is the reaction product of a primary or secondary amine and an aldehyde; and

wherein the base resin is modified with a silane coupling agent.

37. The inhibitor of claim 36, wherein the amine-aldehyde resin comprises a urea-formaldehyde resin having a number average molecular weight (Mn) of greater than 300 g/mole.

38. The inhibitor of claim 36, wherein the amine-aldehyde resin comprises a urea-formaldehyde resin having a concentration of free formaldehyde of less than 5%.

39. The inhibitor of claim 36, wherein the amine-aldehyde resin comprises a urea-formaldehyde resin, wherein the silane coupling agent comprises a substituted silane.

40. The inhibitor of claim 36, wherein the amine-aldehyde resin is the reaction product of an aldehyde and an amine in a molar ratio of 1.5: 1 to 4: 1.

41. The inhibitor of claim 36, wherein the amine-aldehyde resin comprises a urea-formaldehyde resin that is the reaction product of formaldehyde and urea in a molar ratio of 1.75: 1 to 3: 1.

42. The inhibitor of claim 36, wherein the silane coupling agent comprises a ureido substituted silane, an amino substituted silane, a sulfur substituted silane, an epoxy substituted silane, a methacryloyl substituted silane, a vinyl substituted silane, an alkyl substituted silane, a haloalkyl substituted silane, or any combination thereof.

43. The inhibitor of claim 36, wherein the silane coupling agent is selected from ureidoalkyltrialkoxysilanes, aminoalkyl trialkoxysilanes, oligomeric aminoalkyl silanes, or any combination thereof.

44. The inhibitor of claim 36, wherein the silane coupling agent is selected from the group consisting of ureidopropyltrimethoxysilane, ureidopropyltriethoxysilane, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminopropylmethyldiethoxysilane, aminopropylmethyldimethoxysilane, aminoethylaminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane, diethylenetriaminopropyltrimethoxysilane, diethylenetriaminopropyltriethoxysilane, diethylenetriaminopropylmethyldimethoxysilane, diethylenetriaminopropylmethyldiethoxysilane, cyclohexylaminopropyltrimethoxysilane, hexamethylenediaminomethyltriethoxysilane, anilinomethyltrimethoxysilane, anilinomethyltriethoxysilane, and mixtures thereof, Diethylaminomethyltriethoxysilane, (diethylaminomethyl) methyldiethoxysilane, methylaminopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, bis (triethoxysilylpropyl) disulfide, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, mercaptopropylmethyldimethoxysilane, 3-thiocyanatopropyltriethoxysilane, isocyanatopropyltriethoxysilane, glycidoxypropyltrimethoxysilane, glycidoxypropyltriethoxysilane, glycidoxypropylmethyldiethoxysilane, glycidoxypropylmethyldimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, methacryloxypropylmethyldimethoxysilane, methacryloxypropyldimethoxysilane, diethylaminomethyldimethoxysilane, diethylaminomethyldiethoxysilane, mercaptomethyldimethoxysilane, mercaptopropyltrimethoxysilane, mercaptomethyldimethoxysilane, mercaptomethyldimeth, Chloropropyltrimethoxysilane, chloropropyltriethoxysilane, chloromethyltriethoxysilane, chloromethyltrimethoxysilane, dichloromethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, vinyltriacetoxysilane, alkylmethyltrimethoxysilane, vinylbenzylaminotrimethoxysilane, (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, aminopropyltriphenoxysilane, aminopropyltrifurfuroxysilane, aminopropyltris (o-chlorophenoxy) silane, aminopropyltris (p-chlorophenoxy) silane, aminopropyltris (tetrahydrofurfuroxy) silane, ureidosilane, mercaptoethyltriethoxysilane, and vinyltrichlorosilane, Methacryloxypropyltris (2-methoxyethoxy) silane, or any combination thereof.