MX2013010200A - Process for improving the flow rate of an aqueous dispersion. - Google Patents

Abstract

A process for improving the flow rate of an aqueous dispersion which comprises adding a natural polymer to said aqueous system and then adding a synthetic polymer to the aqueous system.

Description

PROCESS TO IMPROVE THE FLOW REGIME OF A DISPERSION AQUEOUS BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The processes for improving the flow regime of an aqueous system comprising the addition of natural polymer to the aqueous system and then the addition of a synthetic polymer to the aqueous system. The natural polymer can be a polysaccharide, such as dextran.

RELATED TECHNIQUE In the production of valuable metals and minerals in mining, mineral bodies are typically in the soil, dispersed in aqueous solutions, treated with agents, and subjected to various processing conditions (temperature, pH, pressure, interlacing speed). The desired result of the mining operation is to generate aqueous dispersions that undergo isolation, separation, or purification of the valuable part of the mineral, whether it is a metal or mineral.

The aqueous dispersions that result from the mining operations subject are composed of: mixtures of water, solids and other materials. Examples of the types of solids are typically found in aqueous dispersions Mineral operations include minerals, metals, metal oxides, metal sulphides, metal hydroxides, salts, organic matter, inorganic matter and others. Of particular interest are aqueous dispersions that are composed of minerals, concentrates, debris and the like, which may contain particles that have morphologies that are not conducive to rapid sedimentation or pumping. Pumped concentrated aqueous dispersions may contain valuable minerals or metals or waste residues. The valuable resources found in aqueous dispersions can include minerals (bauxites, laterites, or sulfides), metals (such as iron, base metals, precious metals, light metals and uranium), coal, and the like. Waste streams consist of gangue minerals and other components with little or no value. Typically, aqueous dispersions are processed by treatment with flocculating or coagulating agents to initiate liquid-solid separation which concentrates the solids portion of the aqueous dispersion in suitable separation processes, eg, centrifugation, concentration, sedimentation, dehydration. , filtration and the like.

The solid-liquid separations facilitated by the use of coagulation and / or flocculating agents are necessary to further concentrate the aqueous dispersions to reduce the associated costs, with the process of transport, calcination, separation, digestion, or storage. Solid-liquid separations are now more difficult because the ore bodies that are processed today contain lower concentrations of valuable minerals and metals and a higher concentration of gangue minerals. The gangue comprises the part of the deposits that can be used or of low value and the gangue typically consists of fine irregularly shaped particles. Solid-liquid separations are accelerated by the use of synthetic or natural polymers before transporting the aqueous dispersion from where it is located or generated to the facility in which it is stored, calcined, separated, or transported. Due to the size and shape of the gangue particles, the gangue minerals are more difficult to agglomerate, therefore, higher doses of synthetic or natural polymeric flocculants are required to achieve the same settling regimes necessary to maintain the flow regimes of cast steel desired. What makes the transport of concentrated aqueous dispersions even more difficult is that the chemicals used to coagulate or flocculate the solids of the aqueous dispersions promote higher rheological parameters, such as more viscosity; high or higher creep tension of concentrated solids and makes solids even more difficult to pump; The use of high molecular weight, synthetic polymer flocculants imparts high rheological characteristics making pumping of aqueous dispersions more difficult, as a consequence the operating cost and profitability are adversely affected. Preferably, the concentrated aqueous dispersions exhibit low yields to allow pumping at low threshold energy levels. In addition, cbntientrated aqueous dispersions must have low viscosity, which should give rise to fast flow rates through mining processes to improve efficiency, productivity and decrease energy costs in mills or refineries. If mining companies continue to be profitable, there is a need for mining operations to be able to process concentrated aqueous dispersions efficiently by reducing the rheological properties of the substrates. t; SUMMARY OF THE INVENTION The description refers to a process to improve I the flow regime of a quje aqueous dispersion; comprises (a) the addition of a natural polymer to the aqueous dispersion, and (b) then the addition of a synthetic polymer to the aqueous dispersion. I By using the defined process it was found that the flow stress of the aqueous dispersion was reduced. The reduction of the elasticity limit of the aqueous dispersion is important due to aqueous suspensions that have a lower elastic limit that can be transported through pipes and other equipment more quickly and efficiently, which results in increased productivity and energy saving. The process is of particular importance because the yield stress is reduced without adversely affecting the rate of sedimentation or the compaction of the solids in the aqueous dispersion. The consequence is that the amount of flocculating agent necessary to promote the sedimentation of the solids can be reduced with consequent cost savings in the flocculating agent. The process is particularly useful when the aqueous dispersion contains high amounts of gangue and / or when the particle forms of the solids in the aqueous dispersion are fine and / or irregularly shaped.

The following definitions and abbreviations will have the following meanings and definitions as set forth in the present description, including drawings and examples.

AA means and refers to acrylic acid.

AM means and refers to acrylamida.

AMPS means and refers to 2-acrylamido-2-methylpropane acid.

The aspect ratio is defined by the ratio between the minimum to the maximum diameter of Feret as measured by X-ray diffraction. The aspect ratio provides an indication of the elongation and sphericity of a particle, where the sphericity of the particle is inversely proportional to the aspect ratio.

Mn is the number average molecular weight determined by SEC-MALLS analysis.

Mw is the weight average molecular weight, determined by SEC-MALLS analysis.

MALLS, means and refers to the dispersion of multi-i-angular laser light.

SEC-MALLS means and refers to a size exclusion chromatography technique using MALLS determines Mw and Mn.

PDI means and refers to the polydispersity index, which is a measure of the distribution of the molecular mass in a given polymer sample and is Mw divided by the number-average molecular weight (n), which represents the distribution of the various molecules. of molecular weights.

Pa is Paséales, a measure of pressure.

"Polysaccharide" means and refers to a dextran having w < 50000.

Polysaccharide B means and refers to a dextran having Mw of 713,000.

Polysaccharide C means and refers to a dextran having Mw of 2,150,000.

Polysaccharide D means and refers to a dextran having Mw of 4370000.LR.

Polysaccharide E means and refers to dextran which has Mw of 8,870,000.

Polysaccharide F means and refers to a dextran having Mw of 9,860,000.

A synthetic polymer is an anionic copolymer available under the trade name Praestol ® 2640 from Ashland Inc., Wilmington, Delaware, E.U.A. ("Ashland") where Mw is approximately 1,270,000, which is prepared by the free radical polymerization of the AA and AM, such that the molar ratio of AA to AM is approximately 2: 3.

Synthetic Polymer B is an anionic copolymer available under the trade name FLOMIN ® ALE 0EH from SNF Floerger, Andrezieu, France, where Mw is approximately 1,760,000, which is prepared by the free radical polymerization of AA and AM, in such a way that The mole ratio of AA to AM is approximately 4: 1.

The synthetic polymer C is an anionic copolymer available under the tradename PRAESTOL ® 2740 from Ashland, where Mw is approximately 1,080,000, which is prepared by the free radical polymerization of AA and AMPS, such that the molar ratio of AA; to AMPS is approximately 5: 1.

The synthetic polymer D is an anionic copolymer, Photafloc 1143.5, available from Neutron Products, Inc., Dickerson, Aryland, E.U.A. which is prepared by the free radical polymerization of AM and AMPS, such that the molar ratio of AM to AMPS is about 4: 1.

The yield stress means and refers to the amount of energy needed to initiate a movement of solids measured by finned rheometry.

DESCRIPTION OF THE DRAWINGS Figure 1 is a graphical representation showing the effect of the ratio of the dose of polysaccharide to the synthetic polymer dose on the yield stress of an aqueous dispersion containing phosphate mineral where a polysaccharide and synthetic polymer were used.

Figure 2 is a bar graph showing how the creep stress is affected by the order of addition of the polysaccharide and the synthetic polymer in an aqueous dispersion containing copper residues.

Figure 3 is a graphical representation showing how the flow regime is affected by the addition of the polysaccharide and the synthetic polymer in an aqueous dispersion containing phosphate mineral.

DETAILED DESCRIPTION OF THE INVENTION Among the natural polymers that can be used in the process are polysaccharides, such as potato starch, xanthan gums, guar gums, dextran, cellulose derivatives and glycosaminoglycans, as well as lignosulfonates.

Preferably, the natural polymer used in the present invention is dextran polysaccharide. Dextran is generally available from various suppliers including Dextran Products Limited, Toronto, Ontario, Canada and USB Corp., Cleveland, Ohio, E.U.A. It is typically used as the polysaccharide is a dextran having a w of from about 5,000 to about 40,000,000, preferably from about 50,000 to about 25,000,000 and more preferably from about 200,000 to about 10,000,000. Typically, the 1 PDI of the polysaccharide is from about 1.0 to about 10.0, more typically from about 1.1 to about 9.0, and more typically from about 1.2 to about 8.0. The people of experts in this technique, after reading this description, will appreciate that all ranges and values within these indicated ranges that are expressly contemplated.

Synthetic polymers that can be used in the process include anionic, cationic, water-soluble nonionic polymers and amphoteric polymers ... For the purpose of this disclosure, the synthetic polymer will include copolymers and terpolymers, as well as homopolymers. Typically, the synthetic polymer used has an Mw of from about 500,000 to about 25,000,000, preferably from about 750,000 to about 20,000,000, and more preferably from about 1,000,000 to about 18 million. The synthetic polymers can be linear, branched, or entangled. Persons skilled in the art, after reading this description, will appreciate that all ranges and values within these ranges are expressly contemplated.

Nonionic polymers include polymers formed from one or more ethylenically unsaturated water soluble nonionic monomers, for example acrylamide, methacrylamide, hydroxyethyl acrylate and N-vinylpyrrolidone, preferably acrylamide. Nonionic polymers include alkoxylated polyvalent alcohols.

Cationic polymers are formed from one or more cationic ethylenically unsaturated monomers optionally with one or more of the nonionic monomers mentioned above. The cationic polymer can also be an amphoteric as long as there are more predominantly cationic groups than anionic groups. The cationic monomers include dialkylamino alkyl (meth) acrylates, diacylamino alkyl (meth) acrylamides, including acid addition and quaternary ammonium salts thereof, diallyl dimethyl ammonium chloride. Typical cationic monomers include methyl chloride quaternary ammonium salts of dimethylamino ethyl acrylate and dimethyl aminoethyl methacrylate. Of particular interest are the copolymer of acrylamide with the quaternary ammonium salts of methyl chloride of dimethylamino ethyl acrylate (ADAME), the copolymer of acrylamide and acrylamidopropyl trimethyl ammonium chloride (APTAC), and the copolymer of acrylamide and ammonium chloride of trimethyl acryloxyethyl (AETAC); and the epichlorohydrin and dimethylamine copolymer.

The anionic polymers are formed from one or more ethylenically unsaturated anionic monomers or a mixture of one or more anionic monomers with one or more of the nonionic monomers mentioned above. Anionic monomers include acrylic acid, methacrylic acid, maleic acid, crotonic acid, itaconic acid, vinyl sulfonic acid, allyl sulfonic acid, 2-acrylamido-2-acid methylpropane sulfonic acid (AMPS), acrylamide, mixtures thereof, and salts thereof.

Of particular interest are copolymers and / or terpolymers of monomers selected from; a group consisting of acrylamide, 2-acrylamido-2-methylpropane sulfonic acid (AMPS), acrylic acid, and (meth) acrylic acid. For example, the anionic polymer can be selected from the group consisting of copolymers derived from 2-acrylamido-2-methylpropane sulfonic acid, copolymers of acrylic acid and acrylamide, homopolymers of acrylic acid, homopolymers of acrylamide, and combinations thereof. Normally used as anionic polymers are the copolymer of sodium acrylate and acrylamide and the copolymer of acrylic acid and acrylamide.

In certain mining segments whereby the pH range is between about 5 and about 10, of particular interest are the copolymers of AMPS and acrylamide in which the molar percentage of AMPS is about 10 percent: mole at about 25 mole percent, and terpolymers of AMPS, acrylamide and acrylic acid, wherein the molar percentage of AMPS is from about 10 mole percent to about 30 mole percent, the mole percentage of acrylamide is from about 40 mole percent to about 60 mole percent, and the The molar percentage of acrylic acid is from about 20 mole percent to about 40 mole percent. Otherwise, homopolymers of acrylic acid or copolymers of acrylic acid and acrylamide are of particular interest.

The synthetic polymer can be prepared by polymerization of a monomer mixture soluble in water or water soluble monomer according to methods well known in the art. Water-soluble monomers are typically water-soluble monomers or water-soluble monomer mixture having a water solubility of at least 5 g in 100 ml of water.

The natural polymer is first added to the aqueous dispersion and this is followed by the addition of the synthetic polymer to the aqueous dispersion. Although not critical, the synthetic polymer is typically added to the aqueous dispersion within one minute, or even seconds, after the natural polymer is added to the aqueous dispersion.

The amount of natural polymers needed to promote lower rheological properties, such as yield stress or viscosity will be dependent on the characteristic properties of the natural polymer, the morphology of the particles in the aqueous dispersion, and the concentration of the aqueous dispersion during separation. liquid-solid. The weight ratio of natural polymer to synthetic polymer is a ratio that effectively reduces the yield stress of the aqueous dispersion is usually a ratio is from about 4: 1 to about 1: 4, and typically varies from about 0.10: 1.0 to about 1.0: 1.0, preferably from about 0.25: 1.0 to about 0.75: 1.0, and more preferably from about 0.25: 1.0 to about 0.50: 1.0. The total amount of natural polymer and polymer: synthetic used to treat the aqueous system varies over wide ranges, but typically ranges from about 1.0 to about 1000 grams per metric ton of treated aqueous system, preferably from about 5.0 to about 500 grams per metric ton, and more preferably from about 10.0 to about 100 grams per metric ton.

The total solids found in the aqueous dispersion can vary within wide ranges, but typically ranges from about 25 g / liter to about 2000 g / liter, such as from about 50 g / liter to 2000 g / liter. The process is particularly useful in reducing the yield stress of the aqueous dispersion wherein the aspect ratio of the solids is less than about 1.0, more particularly when the aspect ratio is less than about 0.5, and / or the solids if the aqueous dispersion contains a substantial amount of gangue.

EXAMPLES In all the examples, unless otherwise indicated, the dextran polysaccharide was used as the natural polymer and anionic copolymers were used as the synthetic polymers. In each set of examples, a comparative example was carried out using only a synthetic polymer, ie, no natural polymer was used. The Mw values of the polysaccharides were determined by SEC-MALLS analysis.

Unless otherwise indicated, the yield stress of the test aqueous dispersion was determined by the addition of 1000 ml of an aqueous dispersion to a graduated cylinder, in which it is first treated by the addition of natural polymer to the Aqueous dispersion, tamping the natural polymer in the dispersion, three times with a plunger that has drilled holes. Next, the synthetic polymer was added to the aqueous dispersion using the same mixing technique and the number of rammers.

The speed at which liquid-solid separation occurred was established by initiating a temporizer at the point where the liquid-solid interface reached the milliliter 1000 mark on the graduated cylinder and then recording the time in which the liquid-solid interface reached each additional group of 50 mi up to the 7.00 mark; my. The sedimentation speed was calculated by subtracting the time recorded in the 900 mi mark from the time recorded in the 700 mi mark.

A compaction value was recorded after 18 hours. Subsequent measurements of elastic limit were taken after the 24-hour mark. To prepare the samples for the analysis of the liquid, I deviated the 1000 milliliter graduated cylinders until only Concentrates that remain in the cylinders. The The resulting samples were transferred quantitatively into beakers of appropriate size. The suspensions in the beakers are allowed to rest for a ji additional period of 4 hours before performing the! yield stress measurements. Í.

The yield stress (in Pa) was measured with a Brookfield HBDVIII Ultra viscometer or rheometer: Brookfield RVDVIII Ultra using finscrews. The tested aqueous dispersion was placed in a beaker of appropriate size for the fin spindle used. The selection of the spindle or rheometer depended on the magnitude of the measured creep voltage range. The spindle of fins1; it was reduced j! 1 even in the aqueous dispersion up to the main mark of the fin spindle. The RHEOCALC ® software was used to Calculate the yield stress using either the Bingham model or the Casson model where indicated1.

The descriptions of the polysaccharides used in the examples are set forth in Table I.

Table I Reagent (g / mol) PDI (Mw / Mn) Polysaccharide A > 50, 000 1.01 Polysaccharide B 713,000 3.62 Polysaccharide C 2, 150, 000 2.09 Polysaccharide D 4,870,000 1.08 Polysaccharide E 8, 870,000 1.01 Polysaccharide F 9, 860, 000 1.30 Examples 1-3 and Comparative Example A These examples illustrate the use of polysaccharides of Table I with a synthetic polymer (Synthetic B'1 Polymer) to concentrate the solids of an aqueous dispersion containing alumina residues, known in the alumina industry as red mud and how this affects the creep tension of the concentrated aqueous dispersion. Comparative Example A used only the synthetic Polymer B as the polymer treatment.

In these examples, dextran polycarcides of variable molecular weight were added, first the addition of synthetic polymer B, a copolymer The amount of solids in the aqueous dispersion was 50 grams per liter. The dose of dextran plus synthetic polymer B in the examples ranged from 250 grams per ton to ^ 00 grams per ton, with a constant dose of synthetic polymer1 of 200 grams per ton. The dextrans used and the percent dosage of dextran to the synthetic polymer B are shown in Table II. Next, the yield stress values of the aqueous dispersions1 were measured and the results are also shown in Table II.

Table II Notes (1) The yield stress value is the average of two samples (2) The yield stress values were calculated with Casson model (3) The synthetic polymer was added before to the polysaccharide The data in Table II show that the yield stress values for the aqueous dispersions containing the alumina residues decreased! when dextran was used together with synthetic polymer B. The data show that the yield stress is reduced as the ratio of the dose of polysaccharide to the synthetic polymer dose increased to an optimum ratio. The data also indicates that the yield stress decreases if the ratio of polysaccharide to synthetic polymer B was less than or equal to about 1: 2 for polysaccharides A and D, and the yield stress decreased if the ratio of polysaccharide to synthetic Polymer B it was less than or equal to about 1: 4 for the polysaccharide F. On the other hand, 'the data suggest that lower molecular weight polysaccharides require lower doses to reach the lower yield strength values.

Examples 4-6 and Comparative Example B Examples 4-6 and Comparative Example B were carried out using an aqueous dispersion containing phosphate mineral. In these examples, dextran polysaccharides of variable molecular weight were added first followed by the addition of a synthetic polymer, an anionic copolymer. The amount of solids in the aqueous dispersion was 130 grams per liter and the dose of dextran plus synthetic polymer A in the examples ranged from 77 grams per ton to 108 grams per ton with a constant dose of synthetic polymer of 62 grams. by Ton. The dextrans used and the percent dose of dextran to the synthetic polymer A are They are shown in Table II. Next, the yield stress values of the aqueous dispersions were measured and the results are also set forth in Table II and in Figure 1.

The data in Table II demonstrate that the yield stress values for aqueous dispersions containing phosphate mineral decreased when dextran was used in conjunction with synthetic polymer AJ. The data show that the yield stress decreases as the ratio of polysaccharide to dosage dosage of synthetic polymer increased to an optimal ratio. The data indicates that the yield stress decreases if the ratio of polysaccharide to synthetic polymer A was less than or equal to about 1: 4 for polysaccharide B and C, and the yield stress decreases if the ratio of polysaccharide to synthetic polymer A was greater than equal to about 1: 4 for polysaccharide D. On the other hand, the data also suggest that lower molecular weight polysaccharides use lower dosages to achieve the [lowest yield stress values.

Examples 7-9 and Comparative Example C Examples 7-9 and Comparative Example C were carried out using an aqueous dispersion containing gold, sulfides, carbonaceous minerals, and other materials. The The amount of solids in the aqueous dispersion was 180 grams per liter and the dose of dextran plus synthetic polymer A in the examples varied from 17 grams per ton to 35 grams per ton with the dose of synthetic polymer remaining constant at 12 grams by Ton. The dextrans used and the percent dose of dextran to synthetic polymer A are set forth in Table II. Next, the yield stress values of the aqueous dispersions were measured and the results are also set forth in Table II.

The data in Table II demonstrate that the yield stress values for aqueous dispersions containing gold feed decreased when dextran was used in conjunction with synthetic polymer A. The data shows that the yield stress decreases more significantly if the ratio of polysaccharide a A synthetic polymer is less than or equal to about 1: 2 for the polysaccharide. The data indicate that the yield stress of the aqueous dispersion containing gold ore decreases if the dextran is used in conjunction with synthetic polymer Á. On the other hand, the data also suggest that lower molecular weight polys- aracides require lower doses to achieve lower yield stress values.

Examples 10-13 and Comparative Example D Examples 10-13 and Comparative Example D were carried out using an aqueous dispersion containing copper, sulfides, debris and other materials. In addition, the polysaccharide E was also tested. The amount of solids in the aqueous dispersion was 90 grams per liter and the dose of dextran plus synthetic polymer A in the examples ranged from about 21 grams per ton to 34 grams per ton with the Synthetic polymer dose that: remains constant at 17 grams per ton. The dextrans used and the percent dose of dextran to the synthetic polymer A are set forth in Table II. Next, the yield stress values of the aqueous dispersions were measured and the results are also set forth in Table II.

The data in Table II demonstrate that the yield stress of the aqueous dispersion containing copper residues and other materials decreased when dextran was used in conjunction with synthetic polymer A. The data shows that the yield stress decreases if the ratio of polysaccharide a A synthetic polymer is less than or equal to approximately 2: 3 polysaccharide B and C, and D. In addition, the data suggest that lower weight, lower molecular polysaccharides require lower doses to achieve the highest yield strength values. low.

Examples 14-16 and Comparative Example E Examples 14-16 and Comparative Example E were carried out using an aqueous dispersion containing copper, sulfides, debris, and other materials. The amount of solids in the aqueous dispersion was 198 grams per liter and the dose of dextran plus synthetic polymer C in the examples ranged from 18 grams per ton to 27 grams per ton with the synthetic polymer dose that! remains constant at 14 grams per ton. The dextran used and the percentage by weight of dextran and synthetic polymers C (dose ratio) are set forth in Table II. The yield stress of the aqueous dispersion was then measured and the results are also set forth in Table II.

The data in Table II demonstrate that the yield stress for aqueous dispersions that: contain copper residues and other materials decreased, when dextran was used in conjunction with Synthetic C-polymer. The data indicates that the yield stress decreases if the ratio of polysaccharide to synthetic Polymer C is: less than or equal to about 2: 3 for polysaccharide B, C, and D.

Examples 1-16 illustrate that the yield stress value exhibited by an aqueous dispersion which is reduced by the addition of a dextran to the aqueous dispersion followed by anionic copolymer, in particular for certain natural polymers with an appropriate Mw and for certain Weight ratios of natural polymer of synthetic polymer. This discovery is important because the reduction of the yield stress of the aqueous dispersion means that the initial energy needed to start pumping the dispersion is reduced. The reduction of the yield stress results in cost savings and an increase in the flow rates when the aqueous dispersion is pumped through the pipes that transport the aqueous dispersion to the facility where the valuable resources are separated from the solids of the aqueous dispersion and when the aqueous dispersion is pumped through the equipment used to separate the valuable resources from the solids in the aqueous dispersion. This can be achieved without significantly increasing the sedimentation rate of the solids in the aqueous dispersion.

Example 17 and Comparative Examples F and Gí For Example 17, the procedure of Examples 10-13 was repeated using a dispersion; aqueous containing copper, sulfides, debris and other materials. However, in Comparative Example F, only the synthetic Polymer A was used, and in Comparative Example G, the order of addition was reversed, that is, the synthetic polymer was added before the natural polymer. The amount of solids in the aqueous dispersion was 59 grams per liter.

The dose of dextran plus synthetic polymer A in the examples remained constant at 34 grams per ton with the dose of synthetic polymer remaining constant at 17 grams per ton. Next, the yield stress values of the aqueous dispersions were measured and the results are shown in Table II.

The data in Table II demonstrate that the creep stress values for aqueous dispersions containing copper moieties, and other materials ¾ decreased when dextran was used in conjunction with synthetic polymer A. Figure 2 indicates that the stress gives creep it decreases if the polysaccharide is added first followed by the addition of synthetic polymer.

Comparative Examples H, I, J and K The procedure of Example 1 was repeated using an aqueous dispersion containing alumina residues, red mud, and other materials, but only Synthetic Polymer B was used to determine the effect on yield stress if natural polymer was not used. The amount of solids in the aqueous dispersion was about 50 grams per liter and the dosage of Synthetic Polymer B in the examples varied from 54 grams per ton to 200 'grams per ton. The yield stress of the aqueous dispersion at Then, it was measured and the results are shown in Table III.

Table III Synthetic alumina B I Remains 47 Polymer 9. 22 - Synthetic alumina B J Remains 50 Polymer 10.60 - Synthetic alumina B K Remains 50 Polymer - - - 9. 82 Synthetic alumina B The data in Table III demonstrate that the yield stress values for the aqueous dispersions containing alumina residues and other materials increased when the dose of synthetic polymer B was increased. This is just the opposite of all previous examples where first the natural polymer was added and then it was followed by the addition of synthetic polymer.

Examples 18-19 and Comparative Example L Examples 18-19 and Comparative Example L were carried out using an aqueous dispersion containing phosphate mineral. In these examples, the polysaccharides, dextran carboxides of variable molecular weight were added first followed by the addition of Synthetic Polymer D, an anionic iopolymer. The amount of solids in the aqueous dispersion was 1099 grams per liter and the dose of dextran, plus synthetic polymer D in the examples ranged from 50 grams per jelly to 75 grams per ton with a constant dose of; synthetic polymer 10 grams per ton. The dextran used and the i1 percent dose of dextran to synthetic polymer C are set forth in Table IV. The flow velocity values for the aqueous dispersions to the potentials of the pump II given below, they were measured and the results are also shown in Table IV and Figure 3.! The data in Table IV demonstrate that the values of material flow regimes for aqueous dispersions containing phosphate mineral increase when dextran was used in conjunction with synthetic polymer D.

The data show that the flow regime when the proportion of the dose of pol i dose of synthetic polymer. : Table IV Substrate Solids Treatment / Metric of '! Pumping Mineral (g / 1) 1099 from phosphate Example Reagent Polymer Current Potential Flow # Natural (GP) (volts) (amps) Dosage for hundred (%) L Polymer 0 30 297 2.8 Synthetic D Only L Polymer 0 34 477 3.3 Synthetic D Only L Polymer 0 31 319 2.8 Synthetic D Only L Polymer 0 35 475 3.3 Synthetic D Only 18 Polysaccharide 50 30 253 2.7 C + Polymer Synthetic D 18 Polysaccharide 50 40 363 3.0 C + Polymer Synthetic D 18 Polysaccharide 50 50 440 3.4 C + Polymer Synthetic D 18 Polysaccharide 50 60 481 4.0 C + Polymer Synthetic D 19 Polysaccharide 75 30 250 2.7 C + Polymer Synthetic D 19 Polysaccharide 75 40 312 2.8 C + Polymer Synthetic D 19 Polysaccharide 75 50 390 3.1 C + Polymer Synthetic D 19 Polysaccharide 75 60 437 3.7 C + Polymer Synthetic D

Claims (20)

1. - A process for improving the flow rate of an aqueous dispersion comprising (a) the addition of a natural polymer to the aqueous dispersion, and (b) then, the addition of a synthetic polymer to the aqueous dispersion, wherein the natural polymer and the synthetic polymer is an amount effective to increase the flow rate of the aqueous dispersion.

2. - The process of claim 1, wherein the natural polymer is a polysaccharide.

3. - The process of claim 2, wherein the polysaccharide is a dextran.

4. - The method of claim 3, wherein the synthetic polymer is selected from the group consisting of water-soluble anionic polymers, cationic polymers, amphoteric polymers, non-ionic polymers and mixtures thereof.

5. - The method of claim 4, wherein the synthetic polymer is an anionic polymer.

6. - The process of claim 5, wherein the anionic polymer is selected from the group consisting of copolymers of 2-acrylamido-2-methylpropane acid derivatives sulfonic acid, copolymers of acrylic acid and acrylamide, homopolymers of acrylic acid, homopolymers of acrylamide, and combinations thereof. ! i 1

7. - The process of claim 5, wherein the anionic polymer comprises a copolymer of sodium arylate and acrylamide or a copolymer of acrylic acid and acrylamide. j,

8. - The process of claim 5, where the pH of the anionic polymer is about 5 to approximately 10. j

9. - The process of claim 5, wherein Mw of the dextran is from about 5,000 to about 40,000.0000. i

10. - The process of claim 9, wherein Mw of the anionic polymer is from about 1,000,000 to about 25,000,000.

11. - The process of claim 10, wherein the dextran PDI is from about 1.0 to about 10.0. ? "

12. - The process of claim 11, · where ! '! weight ratio of natural polymer and polymer! Synthetic is an effective ratio to increase the rate d † flow of the aqueous dispersion.

13. - The process of claim 12 wherein the weight ratio of natural polymer and Synthetic polymer is approximately: 4: 1 a i | approximately 1: 4!

14. - The method of claim 13, wherein the weight ratio is from about 0.10: 1 to about 1.0: 1.0.

15. - The process of claim 13, wherein ! The total solids in the aqueous dispersion is from about 25 grams per liter to about 2,000 grams per liter.

16. - The process of claim 151., wherein the aspect ratio of the solids is less than about 1.0. í

17. - The process of claim 16, wherein the majority of solids by weight comprises a mineral containing phosphate, copper, gold, or other minerals.

18. - The process of claim 16, wherein the majority of the solids by weight comprises gangue. j |

19. - The process of claim 2, wherein the polysaccharide is selected from the group consisting of potato starch, xanthan gums, guar gums, derivatives of ii cellulose and glycosaminoglycans. | I! í1

20. - A process for improving the regime: flow of an aqueous dispersion comprising i ij (a) adding a lignosulfonate to the aqueous dispersion, and [ (b) then the addition of a polymer i: Synthetic to the aqueous dispersion, wherein the ligriosulfonate and the synthetic polymer is an effective amount of a > increase the flow rate of the aqueous dispersion. SUMMARY A process for IMPROVING the flow regime of an aqueous dispersion comprising the addition of a natural polymer to said aqueous system and then the addition of a synthetic polymer to the aqueous system. j