Purification of ores using cationic polymer mixtures

Abstract

Methods of treating a mineral process stream include adding an effective amount of a cationic polymer mixture to the mineral process stream to form a treated mineral process stream; and processing the treated mineral process stream to yield a mineral product. The cationic polymer mixture includes a first cationic polymer having a weight average molecular weight between about 500 g / mol and about 50,000 g / mol, and a second cationic polymer having a weight average molecular weight of about 100,000 g / mol or greater. The cationic polymer mixture obtains a bimodal distribution of weight average molecular weight. The treated mineral process streams obtain a greater yield of mineral product than mineral process streams processed without the cationic polymer mixture, and a greater yield of mineral product than a mineral process stream processed with only one of the cationic polymers of the cationic polymer mixture added thereto.

Description

N12228WO01 (ECO0238WO)PURIFICATION OF ORES USING CATIONIC POLYMER MIXTURESBACKGROUND

[0001] Production of minerals from ore is generally energy intensive and costly. Despite using methods often refined for well over a century, there are still many industry challenges to improve mineral production processes. In particular, use of increasingly lower grade ores of lower available product content and greater mineral complexity present an ongoing need for processes and materials to maximize product yield, conserve energy, and minimize operational costs. Attempts to meet these targets are increasingly faced with complicating factors in the use of low-grade ores. For example, higher levels of impurities capable of “poisoning” the process may become increasingly prevalent as lower grade ores are mined. Continuous mineral purification processes lead to recycling and possible concentration of high levels of impurities obtained from low grade ores, further reducing yield where one or more of the impurities cause poisoning.

[0002] Native impurities found in mineral ores often include organic (carbon-based) compounds. These native organic compounds, or NOC, are carbon-based compounds typically including carboxyl and hydroxyl moieties, as well as other moieties characterized by carbon-heteroatom bonds, including e.g. C-N bonds and C-S bonds. The type and concentration of NOCs that have been identified in various ores globally are reflective of their geographical source, and often include one or more of: alkanols, diols, phenols, polyhydroxylated polymeric and non-polymeric compounds including sugars and polysaccharides as well as phenolic polymers such as lignin and byproducts thereof; polybasic acids, hydroxyacids, polyhydroxy acids, and polyhydroxylated / polycarboxylated organic compounds such as humic substances (including humus acid, humic acid, hymatomelanic acid, fulvic acid, and humin); and chelates, complexes, and supramolecular structures formed form these.

[0003] Such NOC may interact with the components of and / or under the conditions of a mineral purification process when present in a mineral ore process stream, such as an extraction process stream for extracting mineral product from a mineral ore, or a separation process stream for separating a mineral product from other ore components.

[0004] In one such example of such an NOC interaction with a mineral ore process stream, some or all of the compounds listed above may be present in a bauxite ore; wherein processing of the bauxite ore at high pH employing the carboxylic acid groups present in an NOC are converted to sodium carboxylates during the high pH Bayer digestion process. Of these sodium carboxylates, sodium oxalate (Na2C2O4) has been identified as highly detrimental to the Bayer process, acting to severely inhibit operations as evidenced by the plethora of art surrounding isolation and separation of oxalate species from Bayer liquors. In other systems, NOC salts act as surfactants in the system, changing the solubility of materials within the system and e.g. preventing precipitation of desirable mineral product(s).

[0005] Accordingly, NOC present in a mineral ore can affect yield of desirable mineral product obtained from a mineral ore process stream in one or more of three ways: first, by their presence, which reduces mineral yield directly; second, by affecting relative solubility of the mineral product in a mineral ore process stream, thereby reducing the ability to effectively separate the mineral product from the process stream; and third, by causing further undesirable side reactions that interfere with operability of the chemical process to produce yield, that is, by “poisoning” the system.

[0006] It is understood by those of skill that NOC, and in particular hydroxylated organic compounds - can interact with the components of and / or under the conditions of conventional ore purification processes to inhibit mineral precipitation, reduce processing productivity, and / or adversely affect the purity of the produced minerals.

[0007] On an industrial scale, yield of extracted valuable mineral products, such as yield of alumina from bauxite via the Bayer process can be significantly reduced by the presence of NOC in the ore as-mined, or in the ore as purified: that is, many current purification methods are less than completely effective at removing NOC from the mineral ore process stream from which the mineral product is obtained.

[0008] Accordingly, there remains a need in the mining industry to reduce the concentration and / or the impact of organic contaminants in mineral ore slurries. And there remains a need to improve the yield and purity of alumina obtained from Bayer processing of bauxite ores.SUMMARY

[0009] Disclosed herein are methods of improving the yield and / or purity of a mineral obtained from a mineral-bearing ore. In embodiments, the method of improving yield of a mineral obtained from a mineral-bearing ore is a method of improving the yield of alumina obtained from a bauxite ore.

[0010] Accordingly, disclosed herein are methods of treating a mineral process stream, the methods comprising, consisting essentially of, or consisting of adding an effective amount of a cationic polymer mixture to the mineral process stream to form a treated mineral process stream; and processing the treated mineral process stream to yield a mineral product. In some embodiments, the mineral process stream is a mineral ore, such as a bauxite ore. In some embodiments, the mineral process stream is a bauxite process stream. In some embodiments, the mineral process stream is a product derived from Bayer processing of a bauxite ore, that is, a Bayer product. In some embodiments, processing the treated process stream is introducing the treated process stream to one or more steps of a Bayer process. In some embodiments, processing the treated process stream comprises one or more beneficiating, digesting, clarifying, precipitating, classifying, drying, and / or calcining steps.

[0011] In embodiments, the method comprises, consists essentially of, or consists of combining a bauxite ore or a Bayer product with a cationic polymer mixture to form a treated bauxite ore or a treated Bayer product; and processing the treated bauxite ore or treated Bayer product to collect alumina. In embodiments the yield of alumina obtained from the treated bauxite ore or treated Bayer product is at least 0.5% by weight greater and as much as 30% by weight greater than the yield that is obtained from the mineral ore using the same processing methods but without adding the cationic polymer mixture. In embodiments, the yield of the mineral obtained from the treated mineral ore is at least 0.5% by weight greater and as much as 30% by weight greater than the yield that is obtained from the mineral ore using the same processing methods but only one of the cationic polymers of the cationic polymer mixture.

[0012] In any one or more embodiments described herein, a mineral ore is comminuted and / or classified, then combined with a medium comprising water to form a mineral process stream. In embodiments, the mineral ore is a bauxite ore; the mineral product is alumina; and the mineral process stream is a bauxite slurry or a Bayer product, which is a slurry comprising a bauxite ore or a portion of a bauxite ore. In embodiments, the mineral process stream is a Bayer process streamcomprising, consisting essentially of, or consisting of a red mud, a Bayer liquor, or an alumina slurry.

[0013] In embodiments, a cationic polymer mixture is added to a mineral ore slurry neat (that is, 100% solids, or 100% actives); alternatively, the cationic polymer mixture is added to a mineral ore slurry as an aqueous solution or dispersion thereof.

[0014] In embodiments, a first cationic polymer is mixed with a second cationic polymer to form the cationic polymer mixture, and the cationic polymer mixture is added to a mineral process stream to form a treated mineral process stream. In other embodiments, the first cationic polymer and the second cationic polymer are added separately, in any order, to the mineral process stream to form the cationic polymer mixture in situ, to form a treated mineral process stream from the mineral process stream. In such embodiments, the first cationic polymer and the second cationic polymer are added contemporaneously or serially in one or more aliquots to the mineral process stream to form a treated mineral process stream.

[0015] In embodiments, processing the treated mineral process stream comprises, consists essentially of, or consists of one or more of: digesting, clarifying, precipitating, classifying, and calcining the treated mineral process stream. In some such embodiments, the mineral ore is a bauxite ore, and a cationic polymer mixture is added to a bauxite process stream before, during, or after one or more of: comminuting, beneficiating, digesting, clarifying, or precipitating. Accordingly, in any one or more embodiments described herein, a method includes combining a cationic polymer mixture with a bauxite ore to form a treated bauxite ore; adding a medium comprising water to the treated bauxite ore to form a treated bauxite slurry; then subjecting the treated bauxite slurry to one or more digesting, clarifying, precipitating or classifying, stages of a Bayer process. Alternatively in any one or more embodiments described herein, a method includes combining a bauxite ore with a medium comprising water to form a bauxite slurry; adding a cationic polymer mixture to the bauxite slurry to form a treated bauxite slurry; then subjecting the treated bauxite slurry to one or more digesting, clarifying, precipitating or classifying, stages of a Bayer process.

[0016] Also described herein are compositions that are treated mineral process streams, the compositions including a mineral process stream and about 1 ppm to about 10,000 ppm of a cationic polymer based on the weight of the mineral process stream. In embodiments, the cationic polymer mixture consists essentially of about80 wt% to about 99 wt% a first cationic polymer having a weight average molecular weight between about 500 g / mol and about 50,000 g / mol; and about 1 wt% to about 20 wt% of a second cationic polymer having a weight average molecular weight of about 100,000 g / mol or greater. In embodiments, the treated mineral process stream obtains a higher yield of mineral product than the corresponding untreated mineral process stream, where an untreated mineral process stream is a mineral process stream that does not include a cationic polymer mixture. In embodiments, the treated mineral process stream obtains a higher yield of mineral product than the corresponding mineral process stream in the presence of the first cationic polymer but the absence of the second cationic polymer. Similarly, in embodiments, the treated mineral process stream obtains a higher yield of mineral product than the corresponding mineral process stream in the presence of the second cationic polymer but the absence of the first cationic polymer.

[0017] In embodiments, the mineral process stream is or includes a bauxite ore or a Bayer process stream such as a bauxite slurry, a red mud, a Bayer liquor, or even an alumina slurry; and the treated bauxite ore or treated Bayer process stream produces a higher yield of alumina in a precipitation step than the corresponding untreated Bayer process stream, when the treated and untreated Bayer process streams are subjected to the same Bayer processing. In embodiments, the yield of alumina obtained from the treated Bayer process stream is 0.5% to 30% higher by weight than the yield of alumina obtained from the corresponding untreated Bayer process stream, when the treated and untreated Bayer process streams are subjected to the same Bayer processing.

[0018] In embodiments, a treated Bayer process stream produces a higher purity of alumina product than the corresponding untreated Bayer process stream, when both products are subjected to the same Bayer processing. In embodiments, Bayer processing of a treated Bayer process stream obtains an alumina product having an increased alumina content, wherein alumina content of the alumina product is at least 0.1 wt% and as much as 30 wt% greater than the alumina content of an alumina product collected from the corresponding untreated Bayer process stream, when the treated and untreated Bayer process streams are subjected to the same Bayer processing.

[0019] Other objects and features will be in part apparent and in part pointed out hereinafter.DETAILED DESCRIPTION

[0020] Although the present disclosure provides references to preferred embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. Various embodiments will be described in detail with reference to the drawings, wherein reference to various embodiments does not limit the scope of the claims attached hereto. Additionally, any examples set forth in this specification are not intended to be limiting and merely set forth some of the many possible embodiments for the appended claims.

[0021] Definitions

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control. Preferred methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in practice or testing of the present invention. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting.

[0023] Unless otherwise indicated, all parts and percentages recited herein are by weight.

[0024] Unless otherwise indicated, all molecular weights recited herein are weight average molecular weights.

[0025] As used herein, “mineral ore” means a solid rock material excavated from the earth and including a commercially valuable amount of one or more minerals within the rock matrix, or present as a particulate mixture thereof, wherein at least one purification or separation step or process is required to separate a mineral product from one or more native organic compounds also present in the mineral ore. A mineral ore may be “as-mined”, that is, in the form in which it was excavated from the earth; or the mineral ore may be comminuted and / or classified, as specified, as determined by context, or by selected by an operator.

[0026] As used herein, the term “monomer” as applied to indicate a polymerized product thereof, or to indicate incorporation into or within a polymer, or to indicatethe content or chemical structure of a repeat unit of a polymer, indicates within such context the polymerized residue of the monomer, present as a repeat unit within the indicated polymer structure. Accordingly, terms applied to unsaturated polymerizable compounds such as “acrylic acid” refer to either the compound itself, that is, the monomer; or to the repeat unit derived by polymerization thereof, as determined by context.

[0027] As used herein, the term “polymer” means a compound having at least 3 repeating units, that is, repeat units.

[0028] As used herein, the term “soluble” and similar terms such as “solubility” or “dissolved” indicates at least 100 ppm of the indicated compound or material may be dissolved in, or is dissolved in the indicated solvent at 25 °C. In the case of a polymer, the terms “dispersible” or “dispersion” may in some embodiments be recited in place of “soluble” or “solution”, indicating a combination of a polymer with a solvent or solution that results in or develops homogeneous physicochemical properties. Discussions herein related to water solubility are not limited necessarily to solubility in pure water; accordingly, terms such as “aqueous”, “waterbased” and similar terms indicate water that may include, depending on context, one or more organic or inorganic solutes or cosolvents; for example, salts, water miscible liquids, pH adjustment agents, solid particulates, dissolved solids, dissolved gases, polymers, surfactants, hydrotropes, and the like are suitably included in an aqueous solution or dispersion as discussed herein and further in accord with context.

[0029] As used herein, the term “sluny” means a mixture of undissolved particulate solid with water or with an aqueous solution.

[0030] As used herein, the term “medium comprising water” and like terms refers to an a liquid medium that comprises, consists essentially of, or consists of water and optionally one or more water-miscible solvents, together with any gases or solids dissolved therein.

[0031] As used herein, the term “Bayer process” and similar terms in context refer to one or more of the following process steps individually or collectively executed in the processing of alumina, as determined by context: digestion, clarification, precipitation, classification, and calcination. The products of each of these individual processes, or the final product of any two or more of these processes collectively, are referred to herein generally as “Bayer products”. Unless otherwise specified ordetermined by context, general references to the Bayer process or to Bayer products refer to continuous Bayer processes and products thereof.

[0032] As used herein in connection with Bayer processes, “digestion” and similar terms in context refer to compositions or processes wherein an aluminate is extracted from bauxite by contacting bauxite with sodium hydroxide solution (“caustic” or “caustic solution”) to form a Bayer product that is a slurry including dissolved sodium aluminate.

[0033] As used herein in connection with Bayer processes, “clarification” and similar terms in context refer to compositions or processes wherein the Bayer slurry is partitioned and a solid phase residue (“red mud”, a Bayer product) is collected in addition to an aluminate solution (“liquor”, or “Bayer liquor”, a Bayer product). Tn embodiments, the aluminate solution is a saturated aluminate solution. In embodiments, the aluminate solution is a supersaturated aluminate solution.

[0034] As used herein in connection with mineral ores or Bayer processes, the term “classification” and similar terms in context refer generally to compositions or processes for separating and collecting particulates based on size.

[0035] The terms "comprise(s)," "include(s)," "having," "has," "can," "contain(s)," and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that do not preclude the possibility of additional acts or structures. The singular forms "a", "and", and "the" include plural references unless the context clearly dictates otherwise. The present disclosure also contemplates other embodiments "comprising," "consisting of and "consisting essentially of," the embodiments or elements presented herein, whether explicitly set forth or not.

[0036] As used herein, the term "optional" or "optionally" means that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances in which it does not.

[0037] As used herein, the term "about" modifying, for example, the quantity of an ingredient in a composition, concentration, volume, process temperature, process time, yield, flow rate, pressure, and like values, and ranges thereof, employed in describing the embodiments of the disclosure, refers to variation in the numerical quantity that can occur, for example, through typical measuring and handling procedures used for making compounds, compositions, concentrates or use formulations; through inadvertent error in these procedures; through differences in themanufacture, source, or purity of starting materials or ingredients used to cany out the methods, and like proximate considerations. The term "about" also encompasses amounts that differ due to aging of a formulation with a particular initial concentration or mixture, and amounts that differ due to mixing or processing a formulation with a particular initial concentration or mixture. Where modified by the term "about" the claims appended hereto include equivalents to these quantities. Further, where “about” is employed to describe a range of values, for example “about 1 to 5” the recitation means “1 to 5” and “about 1 to about 5” and “1 to about 5” and “about 1 to 5” unless specifically limited by context.

[0038] As used herein, "substantially" means "consisting essentially of, as that term is construed in U.S. patent law, and includes "consisting of as that term is construed in U.S. patent law. For example, a solution that is "substantially free" of a specified compound or material may be free of that compound or material, or may have a minor amount of that compound or material present, such as through unintended contamination, side reactions, or incomplete purification. A “minor amount” may be a trace, an unmeasurable amount, an amount that does not interfere with a value or property, or some other amount as provided in context. A composition that has "substantially only" a provided list of components may consist of only those components, or have a trace amount of some other component present, or have one or more additional components that do not materially affect the properties of the composition. Additionally, "substantially" modifying, for example, the type or quantity of an ingredient in a composition, a property, a measurable quantity, a method, a value, or a range, employed in describing the embodiments of the disclosure, refers to a variation that does not affect the overall recited composition, property, quantity, method, value, or range thereof in a manner that negates an intended composition, property, quantity, method, value, or range. Where modified by the term "substantially" the claims appended hereto include equivalents according to this definition.

[0039] As used herein, any recited ranges of values contemplate all values within the range and are to be construed as support for claims reciting any sub-ranges having endpoints which are real number values within the recited range. By way of a hypothetical illustrative example, a disclosure in this specification of a range of from 1 to 5 shall be considered to support claims to any of the following ranges: 1-5; 1-4; 1 -3; 1 -2; 2-5; 2-4; 2-3; 3-5; 3-4; and 4-5.

[0040] All patents, patent applications (including provisional applications), and publications cited herein are incorporated by reference as if individually incorporated for all purposes.

[0041] First Embodiments

[0042] Described in first embodiments herein are methods of treating a mineral process stream. The methods comprise, consist essentially of, or consist of adding an effective amount of a cationic polymer mixture to the mineral process stream to form a treated mineral process stream; and processing the treated mineral process stream to yield a mineral product. In any one or more first embodiments herein, the cationic polymer mixture comprises, consists essentially of, or consists of about 80 wt% to about 99 wt% a first cationic polymer having a weight average molecular weight between about 500 g / mol and about 50,000 g / mol, and about 1 wt% to about 20 wt% of a second cationic polymer having a weight average molecular weight of about 100,000 g / mol or greater. In any one or more first embodiments herein, the effective amount of the cationic polymer mixture is the amount of the cationic polymer mixture added to the mineral process stream to obtain a yield of mineral product that is at least 0.5% higher by weight than the yield of the mineral product obtained from the mineral process stream processed according to the same process as the treated process stream but in the absence of the cationic polymer mixture.

[0043] In embodiments where the mineral ore is a bauxite ore, and the ore is subsequently processed according to the Bayer process to result in one or more Bayer products, adding a cationic polymer mixture to the bauxite ore or a Bayer product followed by processing the treated bauxite ore or treated Bayer product using one or more processes associated with the Bayer process results in an increased yield and / or purity of alumina compared to the same bauxite ore or Bayer product that is subjected to the same process(es) but in the absence of a cationic polymer mixture.

[0044] In some first embodiments herein, the first and second cationic polymers are chemically identical, and differ solely by molecular weight. In other first embodiments, the first and second cationic polymers are chemically distinct. In any one or more first embodiments herein, the first and second cationic polymers include at least 50 mole% cationic repeat units, where cationic repeat units are repeat units bearing at least a +1 ionic charge covalently bonded to the polymer backbone (and not, for example, present as a counterion). In any one or more first embodiments herein, a cationic repeat unit includes a quaternary ammonium group, where aquaternary ammonium group refers to nitrogen having four nitrogen-carbon bonds. In any one or more first embodiments, the first cationic polymer, the second cationic polymer, or both the first and second cationic polymers include one or more quaternary ammonium-functional repeat units. Examples of quaternary ammonium- functional repeat units include repeat units derived from V,A,A-trimethyl-2-[(l-oxo-2- propenyl)oxy] -ethanaminium chloride, 2-(acryIoYloxy)-A',A',A''- trimethylethanaminium (DMAEA.MCQ); and diallyldialkylammonium chlorides including .-V,<V-dimethyl-A-propenyl-2-propen-l -aminium chloride (diallyldimethylammonium chloride, DADMAC).

[0045] In some first embodiments, the first cationic polymer, the second cationic polymer, or both the first and second cationic polymers include one or more repeat units having structure Iwhich is a repeat unit derived from N,N-dimethyl-N-propenyl-2 -propen- 1 aminium chloride, CAS No. 48042-45-1, commonly referred to as diallyldimethylammonium chloride, or DADMAC. In any one or more first embodiments, the first cationic polymer, the second cationic polymer, or both the first and second cationic polymers are DADMAC homopolymers, that is, polymers consisting of or consisting essentially of repeat units having structure I. In any one or more first embodiments, the first cationic polymer, the second cationic polymer, or both the first and second cationic polymers include at least 50 mole% repeat units having structure I. That is, the first cationic polymer, the second cationic polymer, or both the first and second cationic polymers are DADMAC copolymers having 50 mol% to 99 mol% DADMAC repeat units I, that is, 50 mol% to 55 mol%, or 55 mol% to 60 mol%, or 60 mol% to 65 mol%, or 65 mol% to 70 mol%, or 70 mol% to 75 mol5, or 75 mol% to 80 mol%, or 80 mol% to 85 mol%, or 85 mol% to 90 mol%, or 90 mol% to 95 mol%, or 95 mol% to 97 mol%, or 97 mol% to 99 mol% repeat units having structure I.

[0046] In embodiments the first cationic polymer, the second cationic polymer, or both the first and second cationic polymers include at least 50 mole% repeat units having structure I, and one or more additional repeat units derived from one or more additional monomers, which include any one or more compounds including at least one a, P-unsaturated functionality. In embodiments, the one or more additional monomers are anionic, cationic, nonionic, or betaine type monomers including but not limited to acrylic acid or a conjugate base thereof, methacrylic acid or a conjugate base thereof, acrylamide, methacrylamide, methylolacrylamide, styrene, allylamine, diallylamine, triallylamine, maleic acid or a conjugate base thereof, or itaconic acid or a conjugate base thereof, N,N-dimethylacrylamide, 2-acrylamido-2-methylpropane sulfonic acid or its salts; 7V,.V,N-trimethyl-2-[(l-oxo-2-propenyl)oxy] -ethanaminium chloride, A',A'-dimethyl-A'-propenyl-2-propen-l -aminiurn chloride, 2-(acryloyloxy)- A V,A-triinethylcthanaminium (“DMAEA.MCQ”); and other diallyldialkylammonium halides.

[0047] In any one or more first embodiments, the first cationic polymer, the second cationic polymer, or both the first and second cationic polymers include one or more repeat units having structure II. Repeat unit II is derived from the addition of diethylamine to epichlorohydrin and polymers and copolymers thereof are commonly referred to as “epi-DMA”.11

[0048] Tn any one or more first embodiments, the first cationic polymer, the second cationic polymer, or both the first and second cationic polymers of the cationic polymer mixture are homopolymers consisting of or consisting essentially of repeat units having structure IL In any one or more first embodiments, the first cationic polymer, the second cationic polymer, or both the first and second cationic polymers are cationic copolymers including at least 50 mole% repeat units having structure II. That is, in any one or more first embodiments, the first cationic polymer, the second cationic polymer, or both the first and second cationic polymers include 50 mol% to 99 mol% repeat units II, that is, 50 mol% to 60 mol%, or 60 mol% to 70 mol%, or 70mol% to 80 mol%, or 80 mol% to 90 mol%, or 90 mol% to 99 mol% repeat units having structure II.

[0049] The methodology useful to make the first and second cationic polymers is not particularly limited. One of skill will appreciate that numerous methods of making vinylic polymers including repeat units having structure I are known to those of ordinary skill; similarly, methods of making addition polymers such as polymers having structure II are available in the art. Such methods include polymerization and copolymerization of neat monomers, monomers in solution, and monomers in emulsion, including water-in-oil and oil-in-water emulsion.

[0050] In any one or more first embodiments herein, the first cationic polymer of the cationic polymer mixture has a weight average molecular weight (Mw) of about 500 g / mol to about 50,000 g / mol, where Mwis defined as the average molecular weight of the polymer by mass, further as determined by gel permeation chromatography (GPC). Accordingly, in any one or more first embodiments herein, the first cationic polymer of the cationic polymer mixture has Mwof 500 g / mol to 50,000 g / mol, or 700 g / mol to 50,000 g / mol, or 1000 g / mol to 50,000 g / mol, or 2000 g / mol to 50,000 g / mol, or 3000 g / mol to 50,000 g / mol, or 4000 g / mol to 50,000 g / mol, or 5000 g / mol to 50,000 g / mol, or 7000 g / mol to 50,000 g / mol, or 10,000 g / mol to 50,000 g / mol, or 20,000 g / mol to 50,000 g / mol, or 30,000 g / mol to 50,000 g / mol, or 40,000 g / mol to 50,000 g / mol, or 500 g / mol to 40,000 g / mol, or 500 g / mol to 30,000 g / mol, or 500 g / mol to 20,000 g / mol, or 500 g / mol to 10,000 g / mol, or 500 g / mol to 7,000 g / mol, or 500 g / mol to 5,000 g / mol, or 500 g / mol to 3,000 g / mol, or 500 g / mol to 2,000 g / mol, or 500 g / mol to 1,000 g / mol, or 500 g / mol to 700 g / mol, or 700 g / mol to 1,000 g / mol, or 1,000 g / mol to 2,000 g / mol, or 1,000 g / mol to 2,000 g / mol, or 1,000 g / mol to 2,000 g / mol, or 2,000 g / mol to 3,000 g / mol, or 3,000 g / mol to 4,000 g / mol, or 4,000 g / mol to 5,000 g / mol, or 5,000 g / mol to 6,000 g / mol, or 6,000 g / mol to 7,000 g / mol, or 7,000 g / mol to 8,000 g / mol, or 8,000 g / mol to 9,000 g / mol, or 9,000 g / mol to 10,000 g / mol, or 10,000 g / mol to 15,000 g / mol, or 15,000 g / mol to 20,000 g / mol, or 20,000 g / mol to 25,000 g / mol, or 25,000 g / mol to 30,000 g / mol, or 30,000 g / mol to 35,000 g / mol, or 35,000 g / mol to 40,000 g / mol, or 40,000 g / mol to 45,000 g / mol, or 45,000 g / mol to 50,000 g / mol.

[0051] In any one or more first embodiments herein, the polydispersity index of the first cationic polymer is about 2.5 or less, or between 2.5 and 2.0, or even less than 2.0 as determined using GPC. As used herein, “polydispersity index” or “dispersity”in reference to a polymer means the ratio of Mw / Mn, where Mwis the average molecular weight of the polymer by mass, and Mnis the average molecular weight by number, wherein Mwand Mnare determined using GPC. Accordingly, a monodisperse polymer has PDI of 1.0. In any one or more first embodiments herein, the polydispersity index of the first cationic polymer is about 2.5, about 2.4, about 2.3, about 2.2, about 2.1, about 2.0, about 1.9, about 1.8, about 1.7, about 1.6, about 1.5, about 1.4, about 1.3, about 1.2, about 1.1, or even about 1.0.

[0052] In any one or more first embodiments herein, Mwof the second cationic polymer is at least IxlO5g / mol, such as between IxlO5g / mol and IxlO6g / mol, and can be as high as 5 xlO6g / mol or even higher. In any one or more first embodiments herein, Mwof the second cationic polymer is about 100,000 g / mol to about 10,000,000 g / mol, such as 100,000 g / mol to 9,000,000 g / mol, or 100,000 g / mol to 8,000,000 g / mol, or 100,000 g / mol to 7,000,000 g / mol, or 100,000 g / mol to 6,000,000 g / mol, or 100,000 g / mol to 5,000,000 g / mol, or 100,000 g / mol to 4,000,000 g / mol, or 100,000 g / mol to 3,000,000 g / mol, or 100,000 g / mol to 2,000,000 g / mol, or 100,000 g / mol to 1,000,000 g / mol, or 100,000 g / mol to 500,000 g / mol, or 500,000 g / mol to 10,000,000 g / mol, or 1,000,000 g / mol to 10,000,000 g / mol, or 2,000,000 g / mol to 10,000,000 g / mol, or 3,000,000 g / mol to 10,000,000 g / mol, or 4,000,000 g / mol to 10,000,000 g / mol, or 5,000,000 g / mol to 10,000,000 g / mol, or 6,000,000 g / mol to 10,000,000 g / mol, or 7,000,000 g / mol to 10,000,000 g / mol, or 8,000,000 g / mol to 10,000,000 g / mol, or 9,000,000 g / mol to 10,000,000 g / mol, or 100,000 g / mol to 200,000 g / mol, or 200,000 g / mol to 300,000 g / mol, or 300,000 g / mol to 400,000 g / mol, or 400,000 g / mol to 500,000 g / mol, or 500,000 g / mol to 600,000 g / mol, or 600,000 g / mol to 700,000 g / mol, or 700,000 g / mol to 800,000 g / mol, or 800,000 g / mol to 900,000 g / mol, or 900,000 g / mol to 1,000,000 g / mol, or 1,000,000 g / mol to 1,200,000 g / mol, or 1,200,000 g / mol to 1,400,000 g / mol, or 1,400,000 g / mol to 1,600,000 g / mol, or 1 ,600,000 g / mol to 1,800,000 g / mol, or 1,800,000 g / mol to 2,000,000 g / mol, or 2,000,000 g / mol to 2,200,000 g / mol, or 2,200,000 g / mol to 2,400,000 g / mol, or 2,400,000 g / mol to 2,600,000 g / mol, or 2,600,000 g / mol to 2,800,000 g / mol, or 2,800,000 g / mol to 3,000,000 g / mol, or 3,000,000 g / mol to 3,200,000 g / mol, or 3,200,000 g / mol to 3,400,000 g / mol, or 3,400,000 g / mol to 3,600,000 g / mol, or 3,600,000 g / mol to 3,800,000 g / mol, or 3,800,000 g / mol to 4,000,000 g / mol, or 4,000,000 g / mol to 1,500,000 g / mol, or 4,500,000 g / mol to 5,000,000 g / mol, or 5,000,000 g / mol to 5,500,000 g / mol, or 5,500,000 g / mol to 6,000,000 g / mol, or6,000,000 g / mol to 6,500,000 g / mol, or 6,500,000 g / mol to 7,000,000 g / mol, or 7,000,000 g / mol to 7,500,000 g / mol, or 7,500,000 g / mol to 8,000,000 g / mol, or 8,000,000 g / mol to 8,500,000 g / mol, or 8,500,000 g / mol to 9,000,000 g / mol, or 9,000,000 g / mol to 9,500,000 g / mol, or 9,500,000 g / mol to 10,000,000 g / mol.

[0053] In any one or more first embodiments herein, the polydispersity index of the second cationic polymer is between 2.0 and 5.0, such as between 3.0 and 4.5 or even between 3.5 and 4.5, or between 3.0 and 4.0. In embodiments the poly dispersity index of the first cationic polymer is about 5.0 to about 4.8, or about 4.8 to about 4.6, or about 4.6 to about 4.4, or about 4.4 to about 4.2, or about 4.2 to about 4.0, or about 4.0 to about 3.8, or about 3.8 to about 3.6, or about 3.6 to about 3.4, or about 3.4 to about 3.2, or about 3.2 to about 3.0, or about 3.0 to about 2.8, or about 2.8 to about 2.6, or about 2.6 to about 2.4, or about 2.4 to about 2.2, or about 2.2 to about 2.0, or about 2.0 to about 1.8, or about 1.8 to about 1.6, or about 1 .6 to about 1 .4, or about 1.4 to about 1.2, or even about 1.2 to about 1.0.

[0054] In any one or more first embodiments herein, the first cationic polymer, the second cationic polymer, or both the first cationic polymer and the second cationic polymer are linear. In any one or more first embodiments herein, the first cationic polymer, the second cationic polymer, or both the first cationic polymer and the second cationic polymer are branched, or hyperbranched, or even dendritic.

[0055] In any one or more first embodiments herein, the cationic polymer mixture consists essentially of, or consists of about 80 wt% to about 99 wt% a first cationic polymer having a weight average molecular weight between about 500 g / mol and about 50,000 g / mol, such as about 80 wt%, about 81 wt%, about 82 wt%, about 83 wt%, about 84 wt%, about 85 wt%, about 86 wt%, about 87 wt%, about 88 wt%, about 89 wt%, about 90 wt%, about 91 wt%, about 92 wt%, about 93 wt%, about 94 wt%, about 95 wt%, about 96 wt%, about 97 wt%, about 98 wt%, or about 99 wt% of the first cationic polymer; and about 1 wt% to about 20 wt% of a second cationic polymer having a weight average molecular weight of about 100,000 g / mol or greater, such as about 1 wt%, about 2 wt%, about 3 wt%, about 4 wt%, about 5 wt%, about 6 wt%, about 7 wt%, about 8 wt° / o, about 9 wt%, about 10 wt%, about 1 1 wt%, about 12 wt%, about 13 wt%, about 14 wt%, about 15 wt% , about 16 wt%, about 17 wt%, about 18 wt%, about 19 wt%, or about 20 wt% of the second cationic polymer. Accordingly, in any one or more first embodiments herein, the weight ratio of the first cationic polymer to the second cationic polymer in the cationic polymer mixture isabout 80:20 to about 99:1, such as 80:20, about 81 :19, about 82:18, about 83: 17, about 84:16, about 85:15, about 86:14, about 87:13, about 88: 12, about 89:11, about 90:10, about 91:9, about 92:8, about 93:7, about 94:6, about 97:3, about 98:2, or about 99: 1.

[0056] In any one or more methods of first embodiments herein, the cationic polymer mixture obtains a bimodal distribution of weight average molecular weight when the cationic polymer mixture is analyzed using gel permeation chromatography (GPC; also called size exclusion chromatography). That is, GPC analysis of the cationic polymer mixture manifests as a molecular weight distribution that is clearly identifiable as bimodal to one of ordinary skill in the art of GPC and / or polymer molecular weight analysis, and indicative of a combination of two distinct molecular weight averages. In embodiments, the analyzed weight averages are weight-average molecular weight averages. Accordingly, the first and second cationic polymers of the cationic polymer mixture are sufficiently differentiated by at least molecular weight, and in some cases polydispersity, to obtain a bimodal molecular weight distribution.

[0057] Accordingly, in some first embodiments, the cationic polymer mixtures obtain improved yield of mineral product when about 1 ppm to about 10,000 ppm of the mixture is added to a mineral process stream, forming a treated mineral process stream; and the treated mineral process stream is processed to yield a mineral product. The yield of mineral product obtained from a treated mineral process stream is greater than the yield of the mineral product obtained by adding a “unimodal” molecular weight cationic polymer to the same mineral process stream, where a unimodal polymer has a single weight average molecular weight as determined by GPC. There is nothing in the art related to processing of mineral process streams, such as bauxite ores, bauxite slurries, Bayer products, and the like, to indicate that the cationic polymer mixtures disclosed herein, that is, mixtures of different molecular weight cationic polymers having a bimodal molecular weight distribution, would obtain improved yield of mineral product, such as alumina, relative to use of a unimodal molecular weight cationic polymer.

[0058] In any one or more methods of first embodiments herein, the cationic polymer mixture is added to the mineral process stream “neat”, that is, substantially dry which means including 5 wt% water content or less. In other first embodiments the first cationic polymer, the second cationic polymer, or the cationic polymer mixture isdispersed or dissolved within a dispersion, a latex, or an aqueous solution prior to addition thereof to a mineral process stream. In embodiments an aqueous solution or latex includes water and optionally one or more surfactants and / or one or more water- miscible cosolvents selected from C1-C6 alkanols, ketones, aldehydes, esters, glycols, alkoxyalkanols, and glycol ethers. Where the first cationic polymer, the second cationic polymer, or the cationic polymer mixture is dispersed or dissolved within a polymer latex or an aqueous solution, the first cationic polymer, the second cationic polymer, or the cationic polymer mixture dispersed or dissolved therein is referred to as “polymer actives” or “actives”; and the solution, dispersion, or latex includes about 1 wt% to about 80 wt% actives, for example 1 wt% to 5 wt%, or 5 wt% to 10 wt%, or 10 wt% to 15 wt%, or 15 wt% to 20 wt%, or 20 wt% to 25 wt%, or 25 wt% to 30 wt%, or 30 wt% to 35 wt%, or 35 wt% to 40 wt%, or 40 wt% to 45 wt%, or 45 wt%, to 50 wt%, or 50 wt% to 55 wt%, or 55 3wt% to 60 wt%, or 60 wt% to 65 wt%, or 65 wt% to 70 wt%, or 70 wt% to 75 wt%, or 75 wt% to 80 wt% actives. The concentration of actives in the polymer solution, dispersion, or latex is selected by the operator for ease of use in adding the cationic polymer mixture to the mineral ore, or adding the cationic polymer to one or more containments or tubes, pipes, vessels, etc. during processing of the mineral ore to provide a mineral product, further in consideration of the ease of distributing the cationic polymer mixture within e.g. a comminuted mineral ore or a mineral ore slurry, or a processing product thereof such as a Bayer product.

[0059] In some first embodiments, a first cationic polymer is mixed with a second cationic polymer to form the cationic polymer mixture, and the cationic polymer mixture is added to a mineral process stream to form a treated mineral process stream. In other embodiments, the first cationic polymer and the second cationic polymer are added separately, in any order, to the mineral process stream to form the cationic polymer mixture in situ, to form a treated mineral process stream from the mineral process stream. In such embodiments, the first cationic polymer and the second cationic polymer are added contemporaneously or serially in one or more aliquots to the mineral process stream to form a treated mineral process stream.

[0060] In some first embodiments, the method comprises, consists essentially of, or consists of adding an effective amount of a cationic polymer mixture to a mineral ore to form a treated mineral ore, where the effective amount is the amount of the cationic polymer mixture added to the mineral ore to obtain a yield of mineral that is at least0.5% higher by weight than the yield of mineral obtained from the corresponding untreated mineral ore. In some first embodiments, the method comprises, consists essentially of, or consists of adding an effective amount of a cationic polymer mixture to a bauxite ore to form a treated bauxite ore, where the effective amount is the amount of the cationic polymer mixture added to the bauxite ore to obtain a yield of alumina that is at least 0.5% higher by weight than the yield of alumina obtained from the corresponding untreated bauxite ore. In some first embodiments, the method comprises, consists essentially of, or consists of adding an effective amount of a cationic polymer mixture to a Bayer product to form a treated Bayer product, where the effective amount is the amount of the cationic polymer mixture added to the Bayer product to obtain a yield of alumina that is at least 0.5% higher by weight than the yield of alumina obtained from the corresponding untreated Bayer product.

[0061] In one or more first embodiments described herein, the methods further include processing a treated bauxite ore or a treated Bayer product according to conventional procedures of one or more steps of the Bayer process, wherein the result of Bayer processing of a treated bauxite ore or treated Bayer product is that the actual yield of alumina obtained is increased by at least 0.5 wt% and as much as 30 wt% based on the weight of alumina obtained from the same bauxite ore or Bayer product subjected to the same Bayer processing except that no cationic polymer mixture is added.

[0062] The Bayer process typically comprises: a digestion stage, wherein alumina is extracted by digesting the bauxite in a solution of sodium hydroxide solution (“caustic” or “caustic solution”) forming an aqueous sodium aluminate solution; a clarification stage, wherein a solid phase residue (“red mud”) is separated from a supersaturated aluminate solution (“pregnant liquor”) via sedimentation and filtering; a precipitation stage, wherein alumina is precipitated from the sodium aluminate solution (“liquor” or “Bayer Process liquor”) as crystals (alumina slurry); a classification stage, wherein the crystals are separated from the mixture and collected, leaving what is referred to industrially as “spent liquor” or Bayer spent liquor which is also a Bayer product; and finally, a calcination stage, wherein the collected alumina crystals are calcined and harvested for use in making aluminum metal or another commercial or industrial use. In embodiments, a Bayer spent liquor is recycled within the Bayer process, e.g. added back into the process in the digestion stage. In other embodiments the Bayer spent liquor is evaporated to harvest residual sodiumhydroxide. More detailed descriptions of the Bayer process and its steps are readily available, and further are well known to those of skill.

[0063] In first embodiments, a cationic polymer mixture is added at any one or more of stages of a Bayer process. In any one or more first embodiments herein, a cationic polymer mixture is added to a bauxite ore, such as a comminuted and / or classified bauxite ore, to form a treated bauxite ore; a medium comprising water is added to the treated bauxite ore to form a treated bauxite slurry; and the treated bauxite slurry is subjected to one or more Bayer process steps of digesting, clarifying, precipitating, classifying, drying, and / or calcining to yield an alumina product. In some first embodiments, a bauxite slurry is formed by comminuting and / or classifying a bauxite ore and combining the comminuted and / or classified bauxite ore with a medium comprising water, to form a bauxite slurry; a cationic polymer is added to a bauxite slurry to form a treated bauxite slurry; and the treated bauxite slurry is subjected to one or more Bayer process steps of digesting, clarifying, precipitating, classifying, drying, and / or calcining to yield an alumina product. In some first embodiments, caustic is added to a bauxite slurry to form a red mud; a cationic polymer mixture is added to the red mud to form treated Bayer product that is a treated red mud; and the treated red mud is subjected to one or more Bayer process steps of clarifying (separating), precipitating, classifying, drying, and / or calcining to yield an alumina product. In some first embodiments, caustic is added to a bauxite slurry to form a red mud; then the red mud solids are separated from an aluminate solution, which is a Bayer product called a Bayer liquor; and a cationic polymer mixture is added to the Bayer liquor to form a treated Bayer liquor; and the treated Bayer liquor is subjected to one or more Bayer process steps of precipitating, classifying, drying, and / or calcining to yield an alumina product.

[0064] Accordingly, Bayer processing of a treated bauxite ore or a treated Bayer product formed using the methods of first embodiments herein obtains a higher yield of alumina at the conclusion of the Bayer process, than Bayer processing of the same bauxite ore or Bayer product(s) carried out without the addition of the cationic polymer mixture. Further, in first embodiments, Bayer processing of a treated bauxite ore or a treated Bayer product by the methods of first embodiments herein obtains a higher yield of alumina at the conclusion of the Bayer process than Bayer processing of the same bauxite ore or Bayer product carried out by adding only one of the two cationic polymers of the cationic polymer mixture to the bauxite ore or Bayer product.

[0065] In first embodiments where the Bayer process is a continuous Bayer process, a portion or all of a cationic polymer mixture present in a Bayer product is carried along and recycled within a Bayer process circuit, further without reducing the yield of alumina obtained from the processing.

[0066] We have observed that mineral ores, in particular bauxite ores; and Bayer products obtain improved yield of mineral product by addition of an effective amount of a cationic polymer mixture thereto, further wherein the effective amount of the cationic polymer mixture is the amount of the cationic polymer mixture required to obtain a yield of alumina product that is at least 0.5% higher by weight than the yield of alumina product obtained from the corresponding untreated bauxite ore or untreated Bayer product, processed according to the same process as the treated bauxite ore or treated Bayer product.

[0067] In any one or more first embodiments herein, the effective amount of a cationic polymer mixture added to a mineral ore, that is, the amount of the cationic polymer mixture required to form a treated mineral ore that obtains a yield of mineral product that is at least 0.5% higher by weight than the yield of mineral product obtained from the corresponding untreated mineral ore, is about 1 ppm to about 10,000 ppm by weight of the cationic polymer mixture based on the weight of the mineral ore; for example 1 ppm to 10,000 ppm, 1 ppm to 8,000 ppm, 1 ppm to 6,000 ppm,l ppm to 4,000 ppm, 1 ppm to 2,000 ppm, 1 ppm to 1,000 ppm, 1 ppm to 500 ppm, 1 ppm to 250 ppm, 1 ppm to 100 ppm, 1 ppm to 50 ppm, 1 ppm to 40 ppm, 1 ppm to 30 ppm, 1 ppm to 20 ppm, 1 ppm to 10 ppm, 1 ppm to 5 ppm, 0. 1 ppm to 1 ppm, 10 ppm to 10,000 ppm, 100 ppm to 10,000 ppm, 1,000 ppm to 10,000 ppm, 2,000 ppm to 10,000 ppm, 3,000 ppm to 10,000 ppm, 4,000 ppm to 10,000 ppm, 5,000 ppm to 10,000 ppm, 6,000 ppm to 10,000 ppm, 7,000 ppm to 10,000 ppm, 8,000 ppm to 10,000 ppm, 9,000 ppm to 10,000 ppm, 5 ppm to 10 ppm, 10 ppm to 20 ppm, 20 ppm to 30 ppm, 30 ppm to 40 ppm, 40 ppm to 50 ppm, 50 ppm to 60 ppm, 60 ppm to 70 ppm, 70 ppm to 80 ppm, 80 ppm to 90 ppm, 90 ppm to 100 ppm, 100 ppm to 200 ppm, 200 ppm to 300 ppm, 300 ppm to 400 ppm, 400 ppm to 500 ppm, 500 ppm to 600 ppm, 600 ppm to 700 ppm, 700 ppm to 800 ppm, 800 ppm to 900 ppm, 900 ppm to 1 ,000 ppm, 1,000 ppm to 2,000 ppm, 2,000 ppm to 3,000 ppm, 3,000 ppm to 4,000 ppm, 4,000 ppm to 5,000 ppm, 5,000 ppm to 6,000 ppm, 6,000 ppm to 7,000 ppm, 7,000 ppm to 8,000 ppm, or 8,000 ppm to 9,000 ppm of thecationic polymer mixture is added to the mineral ore to form a treated mineral ore. In any one or more first embodiments herein, the mineral ore is a bauxite ore.

[0068] In any one or more first embodiments herein, the effective amount of a cationic polymer mixture added to a Bayer product, that is, the amount of the cationic polymer mixture required to form a treated Bayer product is about 10 ppm to about 10,000 ppm by weight of the cationic polymer mixture based on the weight of the Bayer product, for example 10 ppm to 10,000 ppm, 10 ppm to 8,000 ppm, 10 ppm to 6,000 ppm, 10 ppm to 4,000 ppm, 10 ppm to 2,000 ppm, 100 ppm to 1,000 ppm, 1 ppm to 500 ppm, 10 ppm to 250 ppm, 10 ppm to 100 ppm, 10 ppm to 50 ppm, 10 ppm to 40 ppm, 10 ppm to 30 ppm, 10 ppm to 20 ppm, 20 ppm to 10,000 ppm, 30 ppm to 10,000 ppm, 40 ppm to 10,000 ppm, 50 ppm to 10,000 ppm, 60 ppm to 10,000 ppm, 70 ppm to 10,000 ppm, 80 ppm to 10,000 ppm, 90 ppm to 10,000 ppm, 100 ppm to 10,000 ppm, 200 ppm to 10,000 ppm, 300 ppm to 10,000 ppm, 400 ppm to 10,000 ppm, 500 ppm to 10,000 ppm, 600 ppm to 10,000 ppm, 700 ppm to 10,000 ppm, 800 ppm to 10,000 ppm, 900 ppm to 10,000 ppm, 1,000 ppm to 10,000 ppm, 2,000 ppm to 10,000 ppm, 3,000 ppm to 10,000 ppm, 4,000 ppm to 10,000 ppm, 5,000 ppm to 10,000 ppm, 6,000 ppm to 10,000 ppm, 7,000 ppm to 10,000 ppm, 8,000 ppm to 10,000 ppm, 9,000 ppm to 10,000 20 ppm to 30 ppm, 30 ppm to 40 ppm, 40 ppm to 50 ppm, 50 ppm to 60 ppm, 60 ppm to 70 ppm, 70 ppm to 80 ppm, 80 ppm to 90 ppm, 90 ppm to 100 ppm, 100 ppm to 200 ppm, 200 ppm to 300 ppm, 300 ppm to 400 ppm, 400 ppm to 500 ppm, 500 ppm to 600 ppm, 600 ppm to 700 ppm, 700 ppm to 800 ppm, 800 ppm to 900 ppm, 900 ppm to 1,000 ppm, 1,000 ppm to 1,200 ppm, 1,200 ppm to 1,400 ppm, 1,400 ppm to 1,600 ppm, 1,600 ppm to 1,800 ppm, 1,800 ppm to 2,000 ppm, 2,000 ppm to 2,500 ppm, 2,500 ppm to 3,000 ppm, 3,000 ppm to3.500 ppm, 3,500 ppm to 4,000 ppm, 4,000 ppm to 4,500 ppm, 4,500 ppm to 5,000 ppm, 5,000 ppm to 5,500 ppm, 5,500 ppm to 6,000 ppm, 6,000 ppm to 6,500 ppm,6.500 ppm to 7,000 ppm, 7,000 ppm to 7,500 ppm, 7,500 ppm to 8,000 ppm, 8,000 ppm to 8,500 ppm, 8,500 ppm to 9,000 ppm, 9,000 ppm to 9,500 ppm, or 9,500 ppm to 10,000 ppm of the cationic polymer mixture by weight is added to a Bayer product to form a treated Bayer product.

[0069] In any one or more first embodiments herein, Bayer processing of a treated bauxite ore or treated Bayer product obtains an increase in yield of collected alumina product of at least 0.5 wt% and as much as 30 wt% based on the weight of alumina product collected from the same weight of bauxite ore or Bayer product, subjected tothe same Bayer processing as the treated ore or treated Bayer product; for example, an increase in weight percent yield of alumina of 0.5% to 30%, or 1% to 30%, or 2% to 30%, or 3% to 30%, or 4% to 30%, or 5% to 30%, or 10% to 30%, or 0.5% to 25%, or 0.5% to 20%, or 0.5% to 15, or 0.5% to 10%, or 0.5% to 5%, or 1% to 20%, or 2% to 20%, or 2% to 15%, or 3% to 15%, or 3% to 13%, or 0.5% to 1%, or 1% to 2%, or 2% to 3%, or 3% to 4%, or 4% to 5%, or 5% to 6%, or 6% to 7%, or 7% to 8%, or 8% to 9%, or 9% to 10%, or 10% to 11%, or 11% to 12%, or 12% to 13%, or 13% to 14%, or 14% to 15%, or 15% to 17%, or 17% to 29%, or 19% to 21%, or 21% to 23%, or 23% to 25%, or 25% to 27%, or 27% to 30%. In some embodiments, Bayer processing of a treated bauxite ore or treated Bayer product results in an increase of alumina yield of at least 1 wt% based on the weight of alumina obtained from the bauxite ore or Bayer product subjected to the same Bayer processing as the treated bauxite ore or treated Bayer product, for example an increase in weight percent yield of alumina of at least 2%, or at least 3%, or at least 4%, or at least 5%, or at least 7%, or at least 10%, or at least 15%, or at least 17%, or at least 20%.

[0070] In any one or more first embodiments herein, a treated mineral process stream produces a higher purity of mineral product than the corresponding untreated mineral process stream, when both mineral process streams are subjected to the same processing steps. In some first embodiments, a treated Bayer process stream produces a higher purity of alumina product than the corresponding untreated Bayer process stream, when both products are subjected to the same Bayer processing steps. In embodiments, Bayer processing of a treated Bayer process stream obtains an alumina product having an increased alumina content, wherein alumina content of the alumina product is at least 0. 1 wt% and as much as 30 wt% greater than the alumina content of an alumina product collected from the corresponding untreated Bayer process stream, when the treated and untreated Bayer process streams are subjected to the same Bayer processing.

[0071] In embodiments, Bayer processing of a treated Bayer process stream obtains an alumina product having an increased alumina content, wherein alumina content of the alumina product is at least 0.1 wt% and as much as 30 wt% greater than the alumina content of an alumina product collected from the corresponding untreated Bayer process stream, when the treated and untreated Bayer process streams are subjected to the same Bayer processing.

[0072] In some first embodiments, the purity of mineral product obtained from a treated mineral process stream is greater than the purity of the mineral product obtained by adding a “unimodal” molecular weight cationic polymer to the same mineral process stream. There is nothing in the art related to processing of mineral process streams, such as bauxite ores, bauxite slurries, Bayer products, and the like, to indicate that the cationic polymer mixtures disclosed herein, that is, mixtures of different molecular weight cationic polymers having a bimodal molecular weight distribution, would obtain improved purity of a mineral product, such as alumina, relative to use of a unimodal molecular weight cationic polymer.

[0073] In embodiments, Bayer processing of a treated bauxite ore or treated Bayer product obtains a collected alumina product having an increased alumina content of at least 0. 1 wt% and as much as 30 wt% more than the corresponding untreated bauxite ore or untreated Bayer product, subjected to the same Bayer processing, for example, an increase in alumina content of about 0.1 wt% to 30 wt%, or 0.2 wt% to 30 wt%, or 0.3 wt% to 30 wt%, or 0.4 wt% to 30 wt%, or 0.5 wt% to 30 wt%, or 1 wt% to 30 wt%, or 2 wt% to 30 wt%, or 3 wt% to 30 wt%, or 4 wt% to 30 wt%, or 5 wt% to 30 wt%, or 10 wt% to 30 wt%, or 0.1 wt% to 25 wt%, or 0.1 wt% to 20 wt%, or 0.1 wt% to 15, or 0.1 wt% to 10 wt%, or 0.1 wt% to 5 wt%, or 0.1 wt% to 4 wt%, or 0.1 wt% to 3 wt%, or or 0.1 wt% to 2 wt%, or 0.1 wt% to 1 wt%, or 0.1 wt% to 0.5 wt%, or 0.5 wt% to 10 wt%, or 0.5 wt% to 9 wt%, or 0.5 wt% to 8 wt%, or 0.5 wt% to 7 wt%, or 0.5 wt% to 6 wt%, or 0.5 wt% to 5 wt%, or 0.5 wt% to 4 wt%, or 0.5 wt% to 3 wt%, or 0.5 wt% to 2 wt%, or 0.5 wt% to 1 wt%, or 1 wt% to 20 wt%, or 1 wt% to 15 wt%, or 1 wt% to 10 wt%, or 1 wt% to 9 wt%, or 1 wt% to 8 wt%, or 1 wt% to 7 wt%, or 1 wt% to 6 wt%, or 1 wt% to 5 wt%, or 3 wt% to 15 wt%, or 3 wt% to 10 wt%, or 5 wt% to 15 wt%, or 5 wt% to 10 wt%. In some embodiments, Bayer processing of a treated bauxite ore or treated Bayer product obtains a collected alumina product having an increased alumina content of at least 0. 1 wt% compared to the alumina content weight obtained from the corresponding untreated bauxite ore or Bayer product that is subjected to the same Bayer processing as the treated bauxite ore or treated Bayer product, for example an increase in alumina content of at least 0.2 wt %, or at least 0.3 wt %, or at least 0.4 wt %, or at least 0.5 wt %, or at least 0.7 wt %, or at least 1 .0 wt %, or at least 1 .5 wt %, or at least 2.0 wt %, or at least 2.5 wt%, or at least 3.0 wt%, or at least 3.5 wt%, or at least 4.0 wt%, or at least 4.5 wt%, or at least5.0 wt% in the alumina product collected from Bayer processing of a treated bauxite ore or treated Bayer product.

[0074] Accordingly, any one or more of the methods described in first embodiments herein may further include an initial determination of benefit for a specific mineral process stream, prior to processing the mineral process stream to obtain the mineral. Determining the benefit for a mineral process stream means determining that the mineral process stream comprises one or more native organic compounds; or determining that addition of a cationic polymer mixture to the mineral process stream will result in increased yield of mineral; or determining both of these. The initial determination of benefit may be whether treatment is needed, and how much of the cationic polymer mixture should be added to the mineral process stream to obtain an increase in yield mineral of at least 0.5%.

[0075] Thus, in one or more first embodiments described herein, the initial determination of benefit comprises, consists essentially of, or consists of determining that a mineral process stream includes a native source of organic compounds. Such methodology is familiar to one of skill and typically involves the thermochemical destruction of organic matter by complete oxidation or combustion to CO2, coupled with infrared spectroscopic analysis of total organic carbon. Suitable methods are outlined, for example, in U.S. Environmental Protection Agency report NCEA-C- 1282, April 2002 (Schumaker). Further, the use of thermochemical methodology to analyze total organic content of ore materials is confirmed by Pulpeiro et al., Light Metals, 1998, 284. The results of such tests may be suitably used to determine if the mineral process stream will obtain a benefit by adding a cationic polymer mixture to the ore or to a slurry thereof. Specifically, the confirmed presence of native organic compounds in a mineral process stream indicates that addition of a cationic polymer mixture thereto will result in a benefit when the treated mineral process stream is processed, by increasing mineral yield obtained from the process. In such embodiments, the amount of the cationic polymer mixture added to a mineral ore or mineral slurry may be selected by the operator to target the amount of organic compounds determined, estimated, or calculated as present in the mineral process stream.

[0076] Further, in one or more first embodiments described herein, the initial determination of benefit comprises, consists essentially of, or consists of determining that addition of a cationic polymer mixture to a mineral process stream will result inincreased yield of mineral. By testing a range of concentrations of a single cationic polymer mixture, and / or by testing a range of chemically distinct cationic polymer mixtures, and / or testing a range of different bimodal distributions, optimum results of mineral yield are obtained. The optimum amount of a selected cationic polymer mixture is then used in the processing plant to obtain optimal yield, that is, optimal benefit obtained by the cationic polymer mixture addition.

[0077] An exemplary but nonlimiting determination related to bauxite ore is carried out comprising, consisting essentially of, or consisting of the following steps, where it will be understood by one of skill that a different mineral process stream may be tested using a different procedure in accordance with the specific ore for which a yield benefit is sought:

[0078] A sample of a Bayer product to be treated (“test slurry”) is obtained from a processing plant and divided into portions; alumina is precipitated from a first test slurry portion to determine yield thereof in the absence of a cationic polymer mixture. In some embodiments, measurement of yield is determined by precipitating, isolating, and weighing the mass of alumina obtained. Then a selected amount of a selected cationic polymer mixture is added to a second portion of the test slurry, followed by alumina precipitation to determine yield of alumina obtained from the slurry.

[0079] The alumina precipitation is carried out using the same materials and the same process steps for the first and second test slurry portions. In some such embodiments, 0.01 g to 10g of a selected cationic polymer mixture is added to the second test slurry portion per liter of the second test slurry. Then the yield of alumina precipitated from first and second test slurries is compared to determine if there is a benefit: specifically, if yield of alumina is increased by adding the selected amount of the selected cationic polymer mixture. Optionally, third, fourth, or a higher number of test slurry aliquots may be used for one or more additional determinations of yield. Additional benefit is obtained in some embodiments by adjusting the amount of the selected cationic polymer mixture added to further increase yield or further increase yield economy (benefit / cost factor of the addition). Further, additional benefit is obtained in some embodiments by varying the chemical structure of the first cationic polymer and / or the second cationic polymer of the cationic polymer mixture to further increase yield or further increase yield economy (benefit / cost factor of the addition). Still further, additional benefit is obtained in some embodiments by varying the ratio of the first cationic polymer to the second cationic polymer in the cationic polymermixture to further increase yield or further increase yield economy; or by varying the molecular weight distribution(s) of the first and / or second cationic polymer; or by varying the polydispersity of the first and / or second cationic polymer in the cationic polymer mixture.

[0080] An alternative method to measure the amount of alumina precipitated from a Bayer product is to directly determine concentration (alumina, caustic and soda) in the test slurry at the start and end of the precipitation process.

[0081] A number of methods are available to assist the skilled artisan in determining yield benefit by precipitation of a mineral from a mineral process stream. Such “precipitation tests” are commonly used by operators to determine a range of issues within a mineral processing circuit and details of the methods used are well documented in the literature. Bayer products are addressed in Watts and Utley, “Volumetric Analysis of Sodium Aluminate Solutions”, Anal. Chem. 1953, 25, 6, 864-867. Other sources of mineral yield determination are suitably employed in combination with the foregoing methods of testing mineral process streams to determine the benefit of adding a cationic polymer mixture.

[0082] In some embodiments, a method of determining yield benefit of a bauxite ore is exemplified in the Experimental Section herein, wherein the method of testing a “blank” synthetic green liquor, seeded with alumina crystals and native organic compounds (NOC) is usefully employed to predict which cationic polymer mixture is optimal for increasing yield of alumina obtained from a particular ore. Thus, in embodiments where yield benefit needs to be determined, alumina seed crystals are added to a Bayer liquor; the alumina seed crystals are first exposed to Bayer liquors that contained NOC prior to their addition to the Bayer liquor for yield determination. The Bayer liquors were either treated with a selected amount of cationic polymer mixture, or left untreated prior to exposing the alumina trihydrate seed to it. The treated or untreated Bayer liquor is agitated at temperature for a period of time, and then the solids from the resulting mixture were collected by vacuum filtration. The NOC-exposed alumina trihydrate solids are then used in a precipitation test to determine the yield. In some such embodiments, the mixture is maintained at a temperature between 60 °C and 100 °C during the mixing, during the agitation, or during the mixing and agitation. In some such embodiments, the precipitate is dried by convection, by heating, or a combination of convection and heating.

[0083] Second embodiments

[0084] Disclosed in second embodiments herein are treated mineral process streams. The treated mineral process streams of second embodiments comprise, consist essentially of, or consist of any of the mineral process streams disclosed in first embodiments herein, combined with any of the cationic polymer mixtures disclosed in first embodiments herein.

[0085] In any one or more first embodi ents herein, a treated mineral process stream comprises, consists essentially of, or consists of mixture of a mineral process stream and about 1 ppm to about 10,000 ppm of a cationic polymer mixture based on the weight of the mineral process stream, for example 1 ppm to 10,000 ppm, 1 ppm to 8,000 ppm, 1 ppm to 6,000 ppm,l ppm to 4,000 ppm, 1 ppm to 2,000 ppm, 1 ppm to 1,000 ppm, 1 ppm to 500 ppm, 1 ppm to 250 ppm, 1 ppm to 100 ppm, 1 ppm to 50 ppm, 1 ppm to 40 ppm, 1 ppm to 30 ppm, 1 ppm to 20 ppm, 1 ppm to 10 ppm, 1 ppm to 5 ppm, 0.1 ppm to 1 ppm, 10 ppm to 10,000 ppm, 100 ppm to 10,000 ppm, 1,000 ppm to 10,000 ppm, 2,000 ppm to 10,000 ppm, 3,000 ppm to 10,000 ppm, 4,000 ppm to 10,000 ppm, 5,000 ppm to 10,000 ppm, 6,000 ppm to 10,000 ppm, 7,000 ppm to 10,000 ppm, 8,000 ppm to 10,000 ppm, 9,000 ppm to 10,000 ppm, 5 ppm to 10 ppm, 10 ppm to 20 ppm, 20 ppm to 30 ppm, 30 ppm to 40 ppm, 40 ppm to 50 ppm, 50 ppm to 60 ppm, 60 ppm to 70 ppm, 70 ppm to 80 ppm, 80 ppm to 90 ppm, 90 ppm to 100 ppm, 100 ppm to 200 ppm, 200 ppm to 300 ppm, 300 ppm to 400 ppm, 400 ppm to 500 ppm, 500 ppm to 600 ppm, 600 ppm to 700 ppm, 700 ppm to 800 ppm, 800 ppm to 900 ppm, 900 ppm to 1,000 ppm, 1 ,000 ppm to 2,000 ppm, 2,000 ppm to 3,000 ppm, 3,000 ppm to 4,000 ppm, 4,000 ppm to 5,000 ppm, 5,000 ppm to 6,000 ppm, 6,000 ppm to 7,000 ppm, 7,000 ppm to 8,000 ppm, or 8,000 ppm to 9,000 ppm of the cationic polymer mixture based on the weight of the ineral process stream. In any one or more first embodiments herein, the mineral process stream is a bauxite ore, a bauxite slurry, or a Bayer product.

[0086] In any one or more second embodiments herein, a treated mineral process stream, such as a treated bauxite ore or a treated Bayer product, obtains an increase in yield of collected mineral product, such as alumina, of at least 0.5 wt% and as much as 30 wt% based on the weight of mineral product collected from the same mineral process stream without the cationic polymer mixture; for example, an increase in weight percent yield of alumina of 0.5% to 30%, or 1% to 30%, or 2% to 30%, or 3% to 30%, or 4% to 30%, or 5% to 30%, or 10% to 30%, or 0.5% to 25%, or 0.5% to20%, or 0.5% to 15, or 0.5% to 10%, or 0.5% to 5%, or 1 % to 20%, or 2% to 20%, or 2% to 15%, or 3% to 15%, or 3% to 13%, or 0.5% to 1%, or 1% to 2%, or 2% to 3%, or 3% to 4%, or 4% to 5%, or 5% to 6%, or 6% to 7%, or 7% to 8%, or 8% to 9%, or 9% to 10%, or 10% to 11%, or 11% to 12%, or 12% to 13%, or 13% to 14%, or 14% to 15%, or 15% to 17%, or 17% to 29%, or 19% to 21%, or 21% to 23%, or 23% to 25%, or 25% to 27%, or 27% to 30% based on the weight of mineral product collected from the same mineral process stream without the cationic polymer mixture. In some embodiments, Bayer processing of a treated bauxite ore or treated Bayer product results in an increase of alumina yield of at least 1 wt% based on the weight of alumina obtained from the bauxite ore or Bayer product subjected to the same Bayer processing as the treated bauxite ore or treated Bayer product, for example an increase in weight percent yield of alumina of at least 2%, or at least 3%, or at least 4%, or at least 5%, or at least 7%, or at least 10%, or at least 15%, or at least 17%, or at least 20%.

[0087] Accordingly, in any one or more second embodiments herein, the treated mineral process stream comprises, consists essentially of, or consists of a treated bauxite process stream. In some second embodiments the treated bauxite process stream is a treated bauxite ore comprising a mixture of a comminuted and / or classified bauxite ore with about 1 ppm to about 10,000 ppm of a cationic polymer mixture based on the weight of the bauxite ore. In some embodiments the treated bauxite process stream is a treated bauxite slurry comprising a mixture of a comminuted and / or classified bauxite ore with a medium comprising water and about 1 ppm to about 10,000 ppm of a cationic polymer mixture based on the weight of the bauxite ore, or the weight of the bauxite process stream.

[0088] In any one or more second embodiments herein, the treated process stream is a treated Bayer process stream comprising, consisting essentially of, or consisting of a treated red mud, a treated Bayer liquor, or a treated alumina slurry. A treated red mud is a treated Bayer process stream comprising, consisting essentially of, or consisting of a red mud combined with about 1 ppm to about 10,000 ppm of a cationic polymer mixture based on the weight of the red mud. A treated Bayer liquor is a treated Bayer process stream comprising, consisting essentially of, or consisting of a Bayer liquor combined with about 1 ppm to about 10,000 ppm of a cationic polymer mixture based on the weight of the Bayer liquor.

[0089] Third embodiments

[0090] Disclosed in third embodiments herein are uses of cationic polymer mixtures of first and second embodiments, having a bimodal molecular weight distribution, to obtain an increase in yield of mineral product collected from a mineral process stream. In some third embodiments, the uses obtain an increase in yield of collected mineral product of at least 0.5 wt% and as much as 30 wt% based on the weight of mineral product collected from the same mineral process stream without using the cationic polymer mixture. In some third embodiments, the uses obtain an increase in yield of collected mineral product of at least 0.1 wt% and as much as 30 wt% compared to the yield of the mineral product collected from the same mineral process stream wherein a “unimodal” molecular weight cationic polymer is used.

[0091] In any one or more third embodiments herein, the mineral process stream is a Bayer process stream; and the use obtains an increase in yield of alumina from the Bayer process stream. In any one or more third embodiments herein, the Bayer process stream is a red mud, a Bayer liquor, or an alumina shirty .

[0092] EXPERIMENTAL SECTION

[0093] Synthetic green liquor (SGL) formation procedure. A predetermined amount of alumina trihydrate solids and sodium hydroxide is dissolved in water. The mixture is heated to a temperature between 95 °C -105 °C. Once all the alumina has dissolved in the caustic solution, the resulting liquor is filtered through a 0.45 micron filter paper to remove any undissolved material. The final SGL is made up to volume with hot deionized water to achieve the desired alumina, caustic and soda concentration.

[0094] Alumina trihydrate seed treatment procedure. Unwashed plant coarse seed is first washed with hot de-ionised water for ten minutes to remove NOC (native organic compounds) that attach to the alumina solids in the Bayer process. The resulting wash water, which is NOC -rich, is then added to plant spent liquor in a ratio of 1 :5.6 to generate an elevated poisoned Bayer spent liquor (PSL). The PSL (500mL) is treated with a selected amount of cationic polymer or left untreated for a control. The bottles containing the PSL are mixed by rotating in a water bath set to 80°C for 60 minutes. The bottles are then removed from the water bath and the contents filtered twice through GF-2 filter papers. The treated and untreated filtrates are then used to prepare the seed for the precipitation step. The treated and untreated PSL (500mL) is added to a bottle that contains washed and dried plant coarse seed (90g, alumina trihydrate).The solids and PSL are mixed in a rotating water bath at 60°C for 15 hours. After 15 hours the solids are collected via vacuum filtration. The collected alumina trihydrate is to be used as seed for the precipitation test. The collected alumina’s moisture content is determined via a gravimetric method so an equivalent mass of dried solids can be calculated for use in the precipitation test.

[0095] Precipitation test. A 250 mb bottle is charged with 30 g of dry equivalent alumina seed crystals formed using the Alumina trihydrate seed treatment procedure. Then 195 mL of an SGL formed using the Synthetic green liquor (SGL) formation procedure is equilibrated at 70 °C, and the heated SGL is added to the bottle containing the seed crystals; the bottle is sealed and shaken by hand to mix the contents. Then the sealed bottle is then mixed in a rotating water bath at 70 °C for 180 minutes. At the end of the 180 minutes, the bottle is opened and 10 mL of a 400 g / L sodium gluconate solution is added to the bottle, and the contents of the bottle are mixed by hand. Finally, the contents of the bottle are filtered by vacuum filtration using a Whatman 540 filter paper; the solids collected on the filter paper (retentate) are washed with hot deionized water, and dried at 105°C. The mass of dry retentate is measured.

[0096] Each Precipitation Test is duplicated, and the average of the retentate mass is reported as the yield, that is, the yield of alumina obtained in the test.

[0097] Polymer Dispersions A-D. A series of DADMAC homopolymers A, B, C, and D, having the molecular weights and polydispersities listed in Table 1, were dispersed in deionized water, either alone or in a blend in accordance with Table 2, such that each of the Polymer Dispersions shown in Table 2 included a total of 30 to 50 wt% polymer.

[0098] Table 1. Molecular weight and polydispersity of DADMAC homopolymers.

[0099] Examples 1-4

[0100] To test the effect of adding polymers to the elevated yield inhibiting NOC Bayer Liquors (PSL), the Polymer Dispersions indicated in Table 2 were applied to a first PSL formed using the Alumina trihydrate seed treatment procedure.The volume of the Polymer Dispersion added to the PSL was adjusted to obtain 3.6g of polymer solids in each bottle, which corresponds to 7300 ppm total polymer by weight based on volume of PSL.

[0101] The resulting alumina trihydrate seed crystals were applied to the Precipitation Test. Each test was run in duplicate, and the average weight of two retentates for each Polymer Dispersion is reported in Table 2.

[0102] Table 2. Yield of retentate obtained in the Precipitation test for Examples 1-4.

[0103] Examples 5-8

[0104] A second PSL was prepared for treatment and exposure to the alumina seed. The Polymer Dispersions indicated in Table 2 were applied to the second PSL using the Alumina trihydrate seed treatment procedure described above. The volume of the Polymer Dispersion added to the second PSL was adjusted to obtain 3.6 g of polymer solids in each bottle, which corresponds to 7300 ppm total polymer by weight based on liquor volume.

[0105] The resulting alumina trihydrate seed crystals were applied to the Precipitation Test. Each test was run in duplicate, and the average weight of two retentates for each Polymer Dispersion is reported in Table 3.

[0106] Table 3. Yield of retentate obtained in the Precipitation test for Examples 5-8.

[0001] The foregoing detailed description has been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. The invention is not limited to the exact details shown and described, for variations obvious to one skilled in the art will be included within the invention defined by the claims.

Claims

WHAT IS CLAIMED IS:1 . A method of treating a bauxite process stream, the method comprising: adding an effective amount of a cationic polymer mixture to the bauxite process stream to form a treated process stream; and processing the treated process stream to yield an alumina product, wherein the cationic polymer mixture consists essentially of: about 80 wt% to about 99 wt% a first cationic polymer having a weight average molecular weight between about 500 g / mol and about 50,000 g / mol, and about 1 wt% to about 20 wt% of a second cationic polymer having a weight average molecular weight of about 100,000 g / mol or greater; and wherein the effective amount of the cationic polymer mixture is the amount of the cationic polymer mixture added to the bauxite process stream to obtain a yield of an alumina product that is at least 0.5% higher by weight than the yield of the alumina product obtained from the bauxite process stream processed according to the same process as the treated process stream but in the absence of the cationic polymer mixture.

2. The method of claim 1 wherein processing the treated process stream is processing the treated process stream using a Bayer process.

3. The method of claim 2 wherein the bauxite process stream is a bauxite slurry comprising a mixture of a comminuted and / or classified bauxite ore with a medium comprising water.

4. The method of any one of claims 1-3 wherein the bauxite process stream is a Bayer process stream.

5. The method of claim 4 wherein the Bayer process stream is a red mud, a clarified red mud, a Bayer liquor, or an alumina slurry comprising alumina trihydrate and caustic-soluble aluminate liquor.

6. The method of claim 4 wherein processing the treated process stream comprises one or more beneficiating, digesting, clarifying, precipitating, classifying, drying, and / or calcining steps.

7. The method of any one of claims 1-6 wherein the effective amount is about 1 ppm to about 10,000 ppm based on the weight of the bauxite process stream.

8. The method of any one of claims 1-7 wherein the processing of the treated slurry yields a greater amount of alumina than the bauxite slurry in the presence of the first cationic polymer but the absence of the second cationic polymer.

9. The method of any one of claims 1-7 wherein the processing of the treated slurry yields a greater amount of alumina than the bauxite slurry in the presence of the second cationic polymer but the absence of the first cationic polymer.

10. The method of any one of claims 1-9 wherein the first cationic polymer and the second cationic polymer consist of poly(epichlorohydrin-dimethylamine).1 1. The method of any one of claims 1-9 wherein the first cationic polymer and the second cationic polymer consist of poly(diallydimethylammonium chloride).

12. The method of any one of claims 1 -1 1 wherein the weight average molecular weight of the first cationic polymer is about 3,000 g / mol to 50,000 g / mol.

13. The method of any one of claims 1-11 wherein the weight average molecular weight of the first cationic polymer is about 10,000 g / mol to about 40,000 g / mol.

14. The method of any one of claims 1-13 wherein the weight average molecular weight of the second cationic polymer is about 100,000 g / mol to about 500,000 g / mol.

15. The method of any one of claims 1-13 wherein the weight average molecular weight of the second cationic polymer is about 200,000 g / mol to about 300,000 g / mol.

16. The method of any one of claims 1-15 wherein the cationic polymer mixture consists essentially of: about 90 wt% to about 98 wt% of the first cationic polymer and about 2 wt% to about 10 wt % of the second cationic polymer.

17. A composition comprising a bauxite process stream; and about 1 ppm to about 10,000 ppm of a cationic polymer mixture based on the weight of the bauxite process stream, wherein the cationic polymer mixture consists essentially of about 80 wt% to about 99 wt% a first cationic polymer having a weight average molecular weight between about 500 g / mol and about 50,000 g / mol; and about 1 wt% to about 20 wt% of a second cationic polymer having a weight average molecular weight of about 100,000 g / mol or greater.

18. The composition of claim 17 wherein the bauxite process stream is a bauxite slurry comprising a mixture of a comminuted and / or classified bauxite ore with a medium comprising water.

19. The composition of claim 17 wherein the bauxite process stream is a Bayer process stream.

20. The composition of claim 19 wherein the Bayer process stream comprises a red mud, a Bayer liquor, or an alumina slurry.21 . The composition of any one of claims 17-20 wherein the first cationic polymer and the second cationic polymer comprise a cationic repeat unit comprising a quaternary ammonium moiety.

22. The composition of any one of claims 17-21 wherein the first cationic polymer, the second cationic polymer, or both the first and the second cationic polymer are homopolymers.

23. The composition of any one of claims 17-22 wherein the first cationic polymer and the second cationic polymer comprise the same cationic repeat unit.

24. The composition of claim 23 wherein the cationic repeat unit has structure I25. The composition of claim 23 wherein the cationic repeat unit has structure II26. The composition of any one of claims 17-25 wherein the weight average molecular weight of the first cationic polymer is about 3,000 g / mol to about 50,000 g / mol.

27. The composition of any one of claims 17-25 wherein the weight average molecular weight of the first cationic polymer is about 10,000 g / mol to about 40,000 g / mol.

28. The composition of any one of claims 17-27 wherein the weight average molecular weight of the second cationic polymer is about 100,000 g / mol to about 500,000 g / mol.

29. The composition of any one of claims 17-27 wherein the weight average molecular weight of the second cationic polymer is about 200,000 g / mol to about 300,000 g / mol.

30. The composition of any one of claims 17-29 wherein the cationic polymer mixture consists essentially of about 94 wt% to about 98 wt% of the first cationic polymer and about 2 wt% to about 6 wt% of the second cationic polymer.

31. Use of a cationic polymer mixture having a bimodal molecular weight distribution to obtain an increase in yield of a mineral product collected from a mineral process stream.

32. The use of claim 31 wherein the cationic polymer mixture consists essentially of about 80 wt% to about 99 wt% a first cationic polymer having a weight average molecular weight between about 500 g / mol and about 50,000 g / mol; and about 1 wt% to about 20 wt% of a second cationic polymer having a weight average molecular weight of about 100,000 g / mol or greater.

33. The use of claim 31 or claim 32 wherein the mineral process stream is a Bayer process stream.

34. The use of any one of claims 31-33 wherein the use obtains an increase in yield of the mineral product of 0.5 wt% to 30 wt% compared to the yield of the mineral product obtained from the mineral process stream without using the cationic polymer mixture.

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