Ore filtration

Abstract

The invention relates to a method for concentrating an aqueous composition of metal ore concentrate, in particular by filtration. The concentration is carried out by partial separation of the water from this composition in the presence of an aqueous concentration agent comprising at least one polymer prepared by radical polymerisation of an unsaturated carboxylic acid. The invention also relates to the filter cake which has a reduced moisture content and which is obtained by using this polymer during the concentration of the metal ore concentrate.

Description

[0001] ORE FILTRATION

[0002] The invention relates to a method for concentrating an aqueous composition of metal ore concentrate, in particular by filtration. The concentration is carried out by partial separation of the water from this composition in the presence of an aqueous concentrating agent comprising at least one polymer prepared by radical polymerization of an unsaturated carboxylic acid. The invention also relates to the filter cake which has a reduced moisture content and which is obtained by using this polymer during the concentration of the metal ore concentrate.

[0003] The method according to the invention is implemented during a mining process for exploiting at least one mineral deposit. These mining processes generally make it possible to obtain at least one metal to be recovered from a metal ore. The mining processes are usually implemented using water as a medium for processing or transporting dry materials. According to the invention, the fraction of the metal ore to be recovered is a concentrate of one or more metals.

[0004] When implementing the concentration method according to the invention, an essential step consists of adding an aqueous concentration agent A comprising at least one polymer P to a metal ore concentrate. This step is therefore generally implemented within a mining process comprising different stages of metal ore processing. Mining processes usually comprise several stages of metal ore processing.Conventionally, a mining process comprises one or more of the following steps: crushing of the metal ore, grinding of the metal ore, in particular dry grinding or wet grinding, generally in water, separation, in particular by flotation, of the metal to be recovered or a derivative of the metal to be recovered and the metal ore residue, purification or enrichment of the metal to be recovered or a derivative of the metal to be recovered, in particular by flotation, concentration of the metal ore concentrate or the metal ore residue, for example by filtration, by sedimentation, by gravity, by use of a thickener, partial separation of the aqueous metal ore residue and part of the water, transport of the metal ore concentrate or the aqueous metal ore residue, storage of the metal ore concentrate, the aqueous metal ore residue.

[0005] To make them easier to handle, aqueous suspensions generally have a low solids concentration. Indeed, the addition of water can lower the viscosity or flow threshold of these suspensions. However, the addition of water leads to problems with water consumption and energy consumption.

[0006] Compatibility with the various constituents of aqueous mineral suspensions prepared from a mining derivative is also an important property to be sought, in particular compatibility with a flocculation agent that can be used to treat the metal ore, the metal ore concentrate or the aqueous residue of metal ore, in particular compatibility with a polyacrylamide or with a polyacrylamide derivative. Similarly, controlling the viscosity of aqueous mineral suspensions prepared from a mining derivative is important, in particular for their pumping, to facilitate their stirring or for their transport. Furthermore, it is important to have methods that allow the flow threshold of the suspensions used to be controlled.

[0007] Importantly, reducing water consumption during the processing of mining by-products must also be sought. Water recovery or recycling during the various stages of mining processes is therefore essential. Both the quantity of separated or recycled water and the quality of the separated or recycled water, particularly its low turbidity, must be sought.

[0008] When concentrating a metal ore, improving the conditions of this concentration, particularly during the separation of water and metal ore, for example by filtration, should have a positive impact on the overall economic and energy balance. For example, controlling the viscosity or the yield point of the medium can reduce the force required for filtration. Improving the efficiency of the concentration should also reduce the number and duration of maintenance operations on the devices used, particularly filtration devices. Avoiding slowdowns, loss of efficiency or blockages when using these devices, for example in the event of partial or total blockage of the filter, must also be sought, in particular to limit the duration of operations, energy consumption, maintenance operations or the use of the various resources required.Effective control of the particle size of the metal ore to be concentrated must also be targeted. Once concentrated after partial water separation, the filter cake must have a low and well-controlled moisture content, particularly to enable its safe and efficient transport. Indeed, transport is generally carried out in bulk and therefore requires high stability, particularly for transport by bulk carrier. Indeed, a low moisture content close to the saturation level will limit water displacement during transport. The slightest reduction in the moisture content can then improve transport conditions and in particular safety, particularly during transport by sea. A poorly controlled moisture content can alter the density of the metal ore concentrate in the hold of a ship and lead to an unbalanced load.Also, too high a humidity level in a metal ore concentrate can cause hydrogen release or heating and lead to a risk of self-combustion.

[0009] GB 2098194 describes a method for separating water from an aqueous suspension of phosphate ore, coal, lignite, clays, or cement. FR 3082124 describes a method for controlling the sedimentation of an aqueous composition to improve its homogeneity but without separating the water it contains. The article by Chaedir Benitta et al. (Advances in dewatering and drying in mineral processing, Drying Technology, 2021) concerns a review of available technologies for water separation or filtration in the mining process.

[0010] The method according to the invention makes it possible to provide a solution to all or part of the problems of the methods of concentrating the aqueous composition of metal ore concentrate of the state of the art.Thus, the invention provides a method for concentrating an aqueous composition comprising at least one concentrate of at least one metal ore comprising the partial separation of water in the presence of an aqueous concentrating agent A comprising at least one polymer P prepared by at least one radical polymerization reaction, at a temperature above 50°C, of ​​at least one anionic monomer M comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts, in the presence of at least one radical-generating compound chosen from hydrogen peroxide, benzoyl peroxide, acetyl peroxide, lauryl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, ammonium persulfate, an alkali metal persulfate, an azo compound, such as 2,2'-azobis(2-(4,5-dihydroimidazolyl)propane, dihydrochloride of.

[0011] 2,2'-azobis(2-methylpropionamidine), diazovalero-nitrile, 4,4'-azobis-(4-cyanovaleric) acid, AZDN or 2,2'-azobisisobutyronitrile, and their respective combinations or associations with an ion selected from Fe 11 , Fe in , Cu 1 , Cu 11 and their mixtures.

[0012] Preferably for the method according to the invention, the partial separation of the water is carried out by centrifugation or by filtration, in particular by fabric or membrane filtration, for example by ceramic membrane. More preferably, the separation is carried out by filtration using a device chosen from a filtration press, a filter press, a rotary filter, a drum filter, a vacuum or suction filter and combinations thereof. The use of a filtration press or a filter press is particularly preferred.

[0013] Preferably according to the invention, the membrane used has a permeability greater than 10 L / (dm 2 .min) at 200 Pa or a permeability less than 150 L / (dm 2 .min) to 200 Pa. More preferably according to the invention, the membrane used has a permeability ranging from 20 L / (dm 2 .min) to 120 L / (dm 2 .min) at 200 Pa or ranging from 50 L / (dm 2 .min) to 100 L / (dm 2 .min) at 200 Pa.

[0014] The conditions for implementing the concentration method according to the invention may vary, in particular the duration or flow rate of the separation step. Preferably for the method according to the invention, the separation time, measured according to the method of the examples, is less than 20 minutes. More preferably, it is less than 10 minutes or less than 5 minutes. According to the invention, the separation time is advantageously greater than 30 seconds or greater than 1 minute. According to the invention, the separation time is the effective duration of the active step during which the water is separated from the metal ore concentrate. Also preferably according to the invention, the separation flow rate of the metal ore concentrate and the water, measured relative to the separation surface and the quantity of metal ore, measured according to the method of the examples, is greater than 950 kg / (m 2.h). More preferably, the separation flow rate is greater than 1,200 kg / (m 2 .h) or greater than 1,300 kg / (m 2 .h). Much more preferably, the separation flow rate is greater than 1,400 kg / (m 2 .h).

[0015] According to the invention, the separation flow rate measures, as a function of time, the mass quantity of metal ore concentrate which is separated as a function of the separation surface, in particular the filtration surface. According to the invention, the separation flow rate measures the concentration flow rate or the filtration flow rate.

[0016] The concentration method according to the invention is carried out from an aqueous composition comprising at least one metal ore concentrate, in particular an aqueous composition of metal ore concentrate obtained after separation of the ore from the gangue generally by flotation or by flotation and decantation.

[0017] Preferably according to the invention, the aqueous composition to be concentrated has a dry matter concentration, preferably of metal ore concentrate, measured by mass loss measurement, greater than 10% by weight or greater than 15% by weight. More preferably, it has a dry matter concentration greater than 20% by weight.

[0018] Also preferably according to the invention, the aqueous composition to be concentrated has a dry matter concentration, preferably of metal ore concentrate, measured by mass loss measurement, of less than 45% by weight or less than 35% by weight or less than 30% by weight. More preferably, it has a dry matter concentration of less than 35% by weight or less than 30% by weight. Also preferably, the aqueous composition to be concentrated has a dry matter concentration, preferably of metal ore concentrate, measured by mass loss measurement, ranging from 10 to 45% by weight or from 10 to 40% by weight or from 10 to 35% by weight or from 10 to 30% by weight.

[0019] Also preferably, the aqueous composition to be concentrated has a dry matter concentration, preferably of metal ore concentrate, measured by mass loss measurement, ranging from 15 to 45% by weight or from 15 to 40% by weight or from 15 to 35% by weight or from 15 to 30% by weight.

[0020] More preferably, the aqueous composition to be concentrated has a dry matter concentration, preferably of metal ore concentrate, measured by mass loss measurement, ranging from 20 to 45% by weight or from 20 to 40% by weight or from 20 to 35% by weight or from 20 to 30% by weight.

[0021] The method according to the invention uses an aqueous composition to be concentrated having a viscosity or a flow threshold which are particularly advantageous. Preferably according to the invention, the aqueous composition to be concentrated has a Brookfield viscosity, measured at 100 rpm and at 25°C, of ​​less than 1,800 mPa.s, preferably less than 1,500 mPa.s or less than 1,200 mPa.s. More preferably, the viscosity is less than 1,000 mPa.s or less than 900 mPa.s. Much more preferably, the viscosity of the aqueous composition to be concentrated is less than 800 mPa.s or less than 700 mPa.s, or even less than 500 mPa.s. Also preferably according to the invention, the aqueous composition to be concentrated has a flow threshold measured at a temperature of 25°C by means of an imposed stress rheometer, equipped with a vane rotor, for a particular torsion torque, less than 20 Pa or less than 10 Pa.

[0022] Preferably, the flow threshold is greater than 1.0 Pa. More preferably, the flow threshold is greater than 1.2 Pa, more preferably greater than 1.5 Pa.

[0023] According to the invention, the yield point, which characterizes the resistance to flow, is measured on a sample of aqueous metal ore composition concentrate. The yield point is the stress that must be applied to a composition in order to cause it to flow. If the stress is insufficient, the composition deforms elastically, whereas if the stress is sufficient, the composition can flow like a liquid.

[0024] According to the invention, the yield point expressed in Pascal (Pa) is measured at a temperature of 25°C using a Brookfield DV3T imposed stress rheometer equipped with a suitable vane rotor. Without destroying the underlying structure, the vane rotor is immersed in the composition up to the first immersion mark. After a waiting time of 1 minute, the measurement is carried out without pre-shearing at a speed of 0.5 rpm. This relatively low speed is preferred in order to minimize the inertia effects of the vane rotor. The variation in the torque measured by the device in order to maintain a rotation speed of 0.5 rpm is monitored as a function of time. The value of the yield limit or yield point of the composition is indicated by the device when this variation becomes zero.

[0025] Preferably, the metal ore is chosen from an ore of lithium, strontium, lanthanides, actinides, uranium, rare earths, titanium, zirconium, vanadium, niobium, chromium, molybdenum, tungsten, manganese, iron, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, cadmium, tin, lead. Particularly preferably, the metal ore is chosen from a copper ore, a molybdenum ore, a nickel ore, in particular a copper ore.

[0026] According to the invention, the metal ore may comprise a metal oxide, a metal sulfide or a metal carbonate.

[0027] When carrying out the concentration method according to the invention, the metal ore concentrate is in the form of particles, preferably in the form of particles, measured by laser diffraction, having a diameter D90 of less than 150 pm, preferably a diameter D90 of less than 100 pm. Preferably according to the invention, the metal ore concentrate particles have a diameter D80 of less than 90 pm, preferably a diameter D80 of less than 80 pm or less than 70 pm or less than 60 pm.

[0028] Generally according to the invention, the particles of metal ore concentrate have a diameter D10 greater than 1 pm, preferably a diameter D80 greater than 2 pm or greater than 5 pm or greater than 10 pm.

[0029] The concentration method according to the invention allows efficient separation of a portion of the water from the aqueous composition of metal ore concentrate to be concentrated.

[0030] Essentially, the concentration method according to the invention uses an aqueous concentration agent A comprising at least one polymer P prepared by at least one radical polymerization reaction of at least one anionic monomer M comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts.

[0031] Preferably for the method according to the invention, the polymer P is used in an amount by dry weight ranging from 20 ppm to 500 ppm, preferably from 30 ppm to 300 ppm or from 40 ppm to 200 ppm, more preferably from 50 ppm to 150 ppm, relative to the amount of metal ore concentrate or dry matter of the composition to be concentrated.

[0032] Also preferably according to the invention, the polymer P has an average molecular weight Mw, measured by CES, ranging from 2,000 g / mol to 20,000 g / mol. More preferably, it ranges from 2,200 g / mol to 10,000 g / mol or from 2,400 g / mol to 9,500 g / mol or from 2,400 g / mol to 8,000 g / mol. Much more preferably, it ranges from 2,400 g / mol to 6,500 g / mol.

[0033] According to the invention, the molecular mass Mw is determined by Size Exclusion Chromatography (SEC) or in English "Gel Permeation Chromatography" (GPC). This technique uses a "Waters" brand liquid chromatography apparatus equipped with a detector. This detector is a "Waters" brand refractometric concentration detector. This liquid chromatography apparatus is equipped with a size exclusion column in order to separate the different molecular weights of the copolymers studied. The liquid elution phase is an aqueous phase adjusted to pH 9.00 using 1 N sodium hydroxide containing 0.05 M NaHCOs, 0.1 M NaNOs, 0.02 M triethanolamine and 0.03% NaNs.

[0034] In a first step, the copolymer solution is diluted to 0.9% dry in the CES solubilization solvent, which corresponds to the liquid elution phase of the CES to which 0.04% dimethylformamide is added, which acts as a flow marker or internal standard. Then, it is filtered at 0.2 qm. 100 qL are then injected into the chromatography apparatus (eluent: an aqueous phase adjusted to pH 9.00 with IN sodium hydroxide containing 0.05 M NaHCCh, 0.1 M NaNCh, 0.02 M triethanolamine and 0.03% NaN3).

[0035] The liquid chromatography apparatus contains an isocratic pump ("Waters" 515) whose flow rate is set at 0.8 mL / min. The chromatography apparatus also includes an oven which itself includes in series the following column system: a precolumn of the "Guard Column Ultrahydrogel Waters" type, 6 cm long and 40 mm inner diameter and a linear column of the "Ultrahydrogel Waters" type, 30 cm long and 7.8 mm inner diameter. The detection system consists of a refractometric detector of the "RI Waters" 410 type. The oven is heated to a temperature of 60°C and the refractometer is heated to a temperature of 45°C. The chromatography apparatus is calibrated using powdered sodium polyacrylate standards of different molecular masses certified by the supplier: Polymer Standards Service or American Polymers Standards Corporation (molecular mass ranging from 900 to 2,250,000 g / mol and polydispersity index ranging from 1.4 to 1.7).

[0036] According to the invention, the polymer P is prepared by a radical polymerization reaction which uses at least one radical-generating compound. Preferably, the radical-generating compound is chosen from hydrogen peroxide, sodium persulfate, potassium persulfate and their respective combinations or associations with an ion chosen from Fe 11 , Fe 111 , Cu 1 , Cu 11 and their mixtures.

[0037] In addition to the monomer M and the radical-generating compound, the polymerization reaction can also be carried out in the presence of at least one compound comprising phosphorus in oxidation state I, preferably a compound chosen from hypophosphorous acid (H3PO2) and a derivative of hypophosphorous acid (H3PO2), preferably a compound comprising at least one hypophosphite ion (H2PO2), more preferably a compound chosen from sodium hypophosphite (EhPChNa), potassium hypophosphite (H2PO2K), calcium hypophosphite ([EhPChkCa) and mixtures thereof.

[0038] The polymerization reaction may also be carried out in the presence of at least one compound comprising phosphorus in oxidation state III, preferably a compound chosen from phosphorous acid and a phosphorous acid derivative, more preferably a compound comprising at least one phosphite ion, in particular a compound chosen from sodium phosphite, calcium phosphite, potassium phosphite, ammonium phosphite and combinations thereof. It may also be carried out in the presence of at least one compound comprising a bisulfite ion, preferably a compound chosen from ammonium bisulfite, an alkali metal bisulfite, in particular sodium bisulfite, potassium bisulfite, calcium bisulfite, magnesium bisulfite and combinations thereof.

[0039] According to the invention, the polymerization reaction can also be carried out in the presence of 0.05 to 5% by weight, relative to the total quantity of monomers, of at least one compound chosen from a xanthate derivative, a mercaptan compound and a compound of in which:

[0040] X independently represents H, Na or K,

[0041] R independently represents a C1-C8-alkyl group, preferably a methyl group; in particular a compound of formula (I) which is disodium trithiocarbonate diisopropionate (DPTTC).

[0042] The polymerization reaction is carried out at a temperature above 50°C. Preferably, the polymerization reaction is carried out at a temperature ranging from 50°C to 98°C, preferably from 50°C to 95°C or from 50°C to 85°C. A higher temperature, in particular above 100°C, can be carried out by adapting the pressure of the reaction medium in order to avoid evaporation.

[0043] According to the invention, the polymerization reaction is preferably carried out in water, in a solvent, alone or in a mixture with water, in particular an alcoholic solvent, in particular isopropyl alcohol. Water is preferred.

[0044] According to the invention, the polymer P may be totally or partially neutralized, in particular at the end of the polymerization reaction. Preferably according to the invention, the neutralization of the polymer P is carried out by neutralizing or salifying all or part of the carboxylic acid functions present within the polymer. Preferably, the neutralization is carried out using a base, for example using an alkali metal derivative or an alkaline earth metal derivative. The preferred bases are chosen from ZnO, MgO, LiOH, NaOH, KOH, NH4OH, Ca(OH)2, Mg(OH)2, monoisopropylamine, triethanolamine, triisopropylamine, 2-amino-2-methyl-1-propanol (AMP), triethylamine, diethylamine, monoethylamine. Particularly preferably, the neutralization is carried out using ZnO, MgO, LiOH, NaOH, Ca(OH)2, Mg(OH)2, alone or in combination.

[0045] Preferably according to the invention, the polymerization reaction involves:

[0046] 100% by weight of anionic monomer M or from 70% to 99.5% by weight of anionic monomer M and from 0.5% to 30% by weight of at least one other monomer.

[0047] Preferably for the method according to the invention, the anionic monomer M comprising at least one polymerizable olefinic unsaturation, comprises one or two carboxylic acid functions, preferably comprises a single carboxylic acid function. More preferably, it is chosen from acrylic acid, methacrylic acid, an acrylic acid salt, a methacrylic acid salt and their mixtures, much more preferably acrylic acid.

[0048] According to the invention, the polymerization reaction can also use at least one other monomer, preferably another monomer chosen from: another anionic monomer, preferably a monomer chosen from acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride and mixtures thereof; 2-acrylamido-2-methylpropane sulfonic acid, a salt of 2-acrylamido-2-methylpropane sulfonic acid,

[0049] 2-(methacryloyloxy)ethanesulfonic acid salt

[0050] 2-(methacryloyloxy)ethanesulfonic acid, sodium methallyl sulfonate, styrene sulfonate and combinations or mixtures thereof; a non-ionic monomer comprising at least one polymerizable olefinic unsaturation, preferably at least one polymerizable ethylenic unsaturation and in particular a polymerizable vinyl function, more preferably a non-ionic monomer chosen from styrene, vinylcaprolactam, esters of an acid comprising at least one monocarboxylic acid function, in particular an ester of an acid chosen from acrylic acid, methacrylic acid, and mixtures thereof, for example hydroxyethylacrylate, hydroxypropylacrylate, hydroxyethylmethacrylate, hydroxypropylmethacrylate, alkyl acrylate, in particular C1-C10-alkyl acrylate, preferably C1-C4-alkyl acrylate, more preferably methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, alkyl methacrylate,in particular C1-C10-alkyl methacrylate, preferably C1-C4-alkyl methacrylate, more preferably methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, aryl acrylate, preferably phenylacrylate, benzylacrylate, phenoxyethylacrylate, aryl methacrylate, preferably phenylmethacrylate, benzylmethacrylate, phenoxyethylmethacrylate; a monomer of formula (II):,

[0051] R 1 and R 2 , identical or different, independently represent H or CH3,

[0052] L 1 independently represents a group chosen from C(O), CH2, CH2-CH2 and O-CH2-CH2-CH2-CH2,

[0053] L 2 independently represents a group chosen from (CEh-CEhO, (CH2CH(CH3)O) y , (CH(CH3)CH2O) Zand their combinations and x, y and z, identical or different, independently represent an integer or decimal number between 0 and 150 and the sum x+y+z is between 10 and 150. Preferably according to the invention, the polymer P is not crosslinked.

[0054] Advantageously according to the invention, the polymer P may be a non-sulfonated polymer, in particular a polymer prepared in the absence of 2-acrylamido-2-methylpropanesulfonic acid or a salt of 2-acrylamido-2-methylpropanesulfonic acid.

[0055] The method according to the invention may comprise the addition of one, two or three different polymers P or at least one additional compound chosen from a lignosulfonate derivative, a silicate, an unmodified polysaccharide and a modified polysaccharide. Essentially according to the invention, the aqueous concentration agent A according to the invention comprises at least one polymer P. It may also comprise other ingredients. When using another ingredient in the agent A according to the invention, it is preferably chosen from at least one derivative S chosen from a ose S1 comprising from 3 to 8 carbon atoms, a ose oligomer S2 comprising from 1 to 10 ose units and a product S3 resulting from the degradation of a saccharide.Preferably according to the invention, the ose SI is chosen from trioses (oses comprising 3 carbon atoms), tetroses (oses comprising 4 carbon atoms), pentoses (oses comprising 5 carbon atoms), hexoses and deoxyhexoses (oses comprising 6 carbon atoms), heptoses (oses comprising 7 carbon atoms), octoses (oses comprising 8 carbon atoms); preferably chosen from glyceraldehyde, dihydroxyacetone, erythrose, threose, erythrulose, deoxyribose, ribose, arabinose, xylose, lyxose, ribulose, xylulose, allose, altrose, galactose, glucose, gulose, idose, mannose, talose, fructose, psicose, sorbose, tagatose, fucose, rhamnose, sedoheptulose, mannoheptulose, heptahydroxyoctanal.

[0056] Also preferably according to the invention, the oligomer S2 is chosen from ose dimers, ose trimers; preferably chosen from dextrose, maltose, lactose, sucrose, maltoriose, maltotetraose, alpha-glucoheptonic acid, beta-glucoheptonic acid.

[0057] Also preferably according to the invention, the product S3 is chosen from aldoses, synthetic monosaccharide derivatives, synthetic disaccharide derivatives; preferably chosen from sorbitol, mannitol, gluconic acid, citric acid, isocitric acid, lactic acid, tartaric acid, the salts of these acids.

[0058] More preferably according to the invention, the derivative S is chosen from sorbitol, mannitol, gluconic acid, citric acid, isocitric acid, lactic acid, tartaric acid, the salts of these acids, dextrose, maltose, glucose, a mixture of glucose and maltose, lactose, sucrose, maltoriose, maltotetraose, alpha-glucoheptonic acid, beta-glucoheptonic acid, the salts of these acids, and combinations of these derivatives.

[0059] Also more preferably for agent A according to the invention, the S / P ratio of the quantities by dry weight of derivative S and polymer P ranges from 0.1 to 10 or from 0.2 to 5 or from 0.3 to 5, preferably from 0.5 to 4 or from 0.5 to 3.

[0060] Preferably according to the invention, the concentration method does not use a surfactant compound, preferably no surfactant ester, in particular polyethylene glycol ester and lauric acid, malic acid octanoate, polyethylene glycol fatty acid ester, polyethylene glycol ester and myristic acid, hexamethyl glycol monooleate.

[0061] In addition to the concentration method, the invention also provides a method for improving the filtration of an aqueous composition which comprises at least one metal ore concentrate. The method for improving the filtration of an aqueous composition according to the invention comprises implementing at least one concentration method defined according to the invention.

[0062] The invention also provides a concentrated aqueous composition comprising at least one metal ore concentrate and an aqueous concentrating agent A comprising at least one polymer P which is prepared by at least one radical polymerization reaction, at a temperature above 50°C, of ​​at least one anionic monomer M comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts, in the presence of at least one radical-generating compound chosen from hydrogen peroxide, benzoyl peroxide, acetyl peroxide, lauryl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, ammonium persulfate, an alkali metal persulfate, an azo compound, such as 2,2'-azobis(2-(4,5-dihydroimidazolyl)propane, dihydrochloride

[0063] 2,2'-azobis(2-methylpropionamidine), diazovalero-nitrile, acid

[0064] 4,4'-azobis-(4-cyanovaleric), AZDN or 2,2'-azobisisobutyronitrile, and their respective combinations or associations with an ion selected from Fe 11 , Fe in , Cu 1 , Cu 11 and their mixtures or concentrated aqueous composition prepared according to the concentration method according to the invention. Preferably according to the invention, the concentrated aqueous composition according to the invention comprises a moisture content of less than 15% by weight, more preferably less than 14% by weight or less than 13% by weight, much more preferably less than 12% by weight or less than 11% by weight, measured by mass loss measurement.

[0065] The invention also provides an aqueous filter cake comprising at least one metal ore concentrate and an aqueous concentrating agent A comprising at least one polymer P which is prepared by at least one radical polymerization reaction, at a temperature above 50°C, of ​​at least one anionic monomer M comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts, in the presence of at least one radical-generating compound chosen from hydrogen peroxide, benzoyl peroxide, acetyl peroxide, lauryl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, ammonium persulfate, an alkali metal persulfate, an azo compound, such as 2,2'-azobis(2-(4,5-dihydroimidazolyl)propane, dihydrochloride of

[0066] 2,2'-azobis(2-methylpropionamidine), diazovalero-nitrile, acid

[0067] 4,4'-azobis-(4-cyanovaleric), AZDN or 2,2'-azobisisobutyronitrile, and their respective combinations or associations with an ion selected from Fe 11 , Fe in , Cu 1 , Cu 11 and their mixtures or aqueous filter cake prepared according to the concentration method according to the invention. Preferably, the filter cake according to the invention comprises a moisture content of less than 15% by weight, more preferably less than 14% by weight or less than 13% by weight, much more preferably less than 12% by weight or less than 11% by weight, measured by mass loss measurement.

[0068] The particular, advantageous or preferred characteristics of the concentration method according to the invention define methods for improving filtration, concentrated aqueous compositions and aqueous filter cakes which are also particular, advantageous or preferred.

[0069] The following examples illustrate the various aspects of the invention.

[0070] EXAMPLES

[0071] Preparation of aqueous concentrating agents according to the invention

[0072] Aqueous agent Al

[0073] In a 1 L reactor equipped with mechanical stirring, oil bath heating and peristaltic pumps, 209.7 g of water, 0.08 g of iron sulfate heptahydrate and 0.011 g of copper sulfate pentahydrate are weighed. The whole is then heated to 95°C and 302.5 g of acrylic acid and 13 g of water, 25.6 g of sodium hypophosphite monohydrate dissolved in 29 g of water, 20.46 g of 130 V hydrogen peroxide diluted with 25 g of water are added over 120 minutes using peristaltic pumps. Then, heating is carried out for 60 minutes at 95°C. The whole is then cooled, neutralized with 50% sodium hydroxide in water to pH 8.5 and diluted to obtain a dry matter content of 40%. The aqueous agent Al is obtained, comprising the polymer Pl sodium polyacrylate with Mw 4,400 g / mol.

[0074] Aqueous agent A2

[0075] In a beaker, 142.9 g of an aqueous concentrating agent prepared according to the method for preparing aqueous agent A1 are weighed and then 50 g of a derivative S1 (glucose syrup with 80% dry extract by weight, CSweet M01658 “Cargill”) and 45 g of water are added, with stirring using a “VMI” turbine 30 motor at 1000 rpm. The aqueous concentrating agent A2 comprising the polymer PI and the derivative SI in a mass ratio of 60 / 40 is obtained.

[0076] Evaluation of methods for concentrating aqueous compositions of copper ore concentrate according to the invention

[0077] An aqueous composition comprising a copper ore concentrate is taken from the outlet of a thickener of a copper mine in Chile after crushing, grinding, flotation of the ore and separation of the copper concentrate and the gangue then thickening of the copper concentrate. This starting composition is stirred in order to make it homogeneous then characterized to evaluate its properties: specific density by picnometric method using a picnometer, particle size distribution by laser diffraction method using a diffractometer (“Mastersizer Malvem” 3000), concentration (% by weight) in copper concentrate by X-ray diffraction method using a “Bruker” D2-Phaser diffractometer, viscosity (mPa.s) by Brookfield measurement (rotary module) and flow threshold by “Haake” measurement (Vane cup) using a “Haake” Viscotester 550 viscometer, solid mass content by mass loss measurement by heating using an oven for 1 hour at 120°C.

[0078] The results are presented in Table 1.

[0079] Table 1

[0080] The concentration method is implemented by filtration of the aqueous composition comprising the copper ore concentrate; it is carried out using: a metal beaker equipped with a piston pump capable of feeding the saturation chamber, a saturation chamber (38 mm thick) comprising a filter (W-TA 301 “Roxia”), polypropylene fabrics with a diameter of 0.078 m, with a surface area of ​​0.0048 m 2 , 1.8 mm thick, 1100 g / m density 2 , permeability 70 L / (dm 2 .min) at 200 Pa.

[0081] In the beaker, the aqueous composition comprising the copper ore concentrate (65% by weight) and, optionally, the aqueous concentration agent Al or A2 according to the invention in different quantities (expressed in ppm by weight of dry matter of the agent Al or A2 relative to the quantity of dry matter of copper concentrate) is introduced, then the composition, optionally comprising the aqueous concentration agent, is introduced into the saturation chamber by means of the pump. The pressure (65+ / - 3 kPa) is applied for a time t in order to filter the concentrate by separating the water by means of the filter. Then, the filter cake is evacuated from the saturation chamber and the filter is dried for 2 minutes by blower (65+ / -3 kPa). After filtration, the humidity level (% by weight), the thickness of the filter cake (mm) are measured and the flow rate (kg / (m 2 xh)). The results are presented in Table 2.

[0082] Table 2

Claims

CLAIMS 1. Method for concentrating an aqueous composition comprising at least one concentrate of at least one metal ore comprising the partial separation of water in the presence of an aqueous concentrating agent A comprising at least one polymer P prepared by at least one radical polymerization reaction, at a temperature above 50°C, of ​​at least one anionic monomer M comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts, in the presence of at least one radical-generating compound chosen from hydrogen peroxide, benzoyl peroxide, acetyl peroxide, lauryl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, ammonium persulfate, an alkali metal persulfate, an azo compound, such as 2,2'-azobis(2-(4,5-dihydroimidazolyl)propane, dihydrochloride of 2,2'-azobis(2-methylpropionamidine), diazovalero-nitrile, acid 4,4'-azobis-(4-cyanovaleric), AZDN or 2,2'-azobisisobutyronitrile, and their respective combinations or associations with an ion selected from Fe 11 , Fe 111 , Cu 1 , Cu 11 and their mixtures.

2. Method according to claim 1, wherein the partial separation of the water is carried out by centrifugation or by filtration, in particular by filtration by fabrics or by membrane, for example by ceramic membrane, preferably by filtration by means of a device chosen from a filtration press, a filter press, a rotary filter or a drum filter, a vacuum or suction filter and combinations thereof.

3. Method according to one of claims 1 or 2 for which: • the separation time, measured according to the method of the description, is less than 20 minutes, preferably less than 10 minutes or less than 5 minutes; or for which the separation time is advantageously greater than 30 seconds or greater than 1 minute; or • the separation rate of the metal ore concentrate and water, measured in relation to the separation surface and the quantity of metal ore, measured according to the method of the description, is greater than 950 kg / (m 2 .h), plus preferably greater than 1,200 kg / (m 2 .h) or greater than 1,300 kg / (m 2 .h), preferably greater than 1,400 kg / (m 2 .h).

4. Method according to one of claims 1 to 3 for which: • the aqueous composition to be concentrated has a concentration of dry matter, preferably of metal ore concentrate, measured by mass loss measurement: greater than 10% by weight or greater than 15% by weight or even greater than 20% by weight; or less than 45% by weight or less than 35% by weight or less than 30% by weight, preferably less than 35% by weight or less than 30% by weight; or ranging from 10 to 45% by weight or from 10 to 40% by weight or from 10 to 35% by weight or from 10 to 30% by weight or from 15 to 45% by weight or from 15 to 40% by weight or from 15 to 35% by weight or from 15 to 30% by weight or from 20 to 45% by weight or from 20 to 40% by weight or from 20 to 35% by weight or from 20 to 30% by weight; or • the aqueous composition to be concentrated has: a Brookfield viscosity, measured at 100 rpm and at 25°C, of ​​less than 1,800 mPa.s, preferably less than 1,500 mPa.s or less than 1,200 mPa.s, more preferably less than 1,000 mPa.s or less than 900 mPa.s, much more preferably less than 800 mPa.s or less than 700 mPa.s, or even less than 500 mPa.s; or a flow threshold measured at a temperature of 25°C by means of an imposed stress rheometer, equipped with a vane rotor, for a particular torque, less than 20 Pa or less than 10 Pa; or a flow threshold greater than 1.0 Pa, preferably greater than 1.2 Pa, more preferably greater than 1.5 Pa; or for which: the metal ore is chosen from an ore of lithium, strontium, lanthanides, actinides, uranium, rare earths, titanium, zirconium, vanadium, niobium, chromium, molybdenum, tungsten, manganese, iron, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, cadmium, tin, lead; or. • the metal ore comprises a metal oxide, a metal sulfide or a metal carbonate; or • the metal ore concentrate is in the form of particles, preferably in the form of particles, measured by laser diffraction, having a diameter D90 of less than 150 pm, preferably a diameter D90 of less than 100 pm, or having a diameter D80 of less than 90 pm, preferably a diameter D80 of less than 80 pm or less than 70 pm or less than 60 pm.

5. Method according to one of claims 1 to 4 for which the aqueous concentration agent A defined according to one of the preceding claims also comprises at least one derivative S chosen from an ose S1 comprising from 3 to 8 carbon atoms, an ose oligomer S2 comprising from 1 to 10 ose units and a product S3 resulting from the degradation of a saccharide, preferably: an ose SI chosen from trioses (oses comprising 3 carbon atoms), tetroses (oses comprising 4 carbon atoms), pentoses (oses comprising 5 carbon atoms), hexoses and deoxyhexoses (oses comprising 6 carbon atoms), heptoses (oses comprising 7 carbon atoms), octoses (oses comprising 8 carbon atoms);preferably chosen from glyceraldehyde, dihydroxyacetone, erythrose, threose, erythrulose, deoxyribose, ribose, arabinose, xylose, lyxose, ribulose, xylulose, allose, altrose, galactose, glucose, gulose, idose, mannose, talose, fructose, psicose, sorbose, tagatose, fucose, rhamnose, sedoheptulose, mannoheptulose, heptahydroxyoctanal, or an oligomer S2 chosen from ose dimers, ose trimers; preferably chosen from dextrose, maltose, lactose, sucrose, maltoriose, maltotetraose, alpha-glucoheptonic acid, beta-glucoheptonic acid, or a product S3 chosen from aldoses, synthetic monosaccharide derivatives, synthetic disaccharide derivatives; preferably chosen from sorbitol, mannitol, gluconic acid, citric acid, isocitric acid, lactic acid, tartaric acid, the salts of these acids;more preferably an S derivative chosen from sorbitol, mannitol, gluconic acid, citric acid, isocitric acid, lactic acid, tartaric acid, the salts of these acids, dextrose, maltose, glucose, a mixture of glucose and maltose, lactose, sucrose, maltoriose, maltotetraose, alpha-glucoheptonic acid, beta-glucoheptonic acid, the salts of these acids, and; combinations of these derivatives; also preferably, the S / P ratio of the quantities by dry weight of derivative S and polymer P ranges from 0.1 to 10 or from 0.2 to 5 or from 0.3 to 5, preferably from 0.5 to 4 or from 0.5 to 3.

6. Method according to one of claims 1 to 5 for which: • the polymer P is used in a quantity by dry weight ranging from 20 ppm to 500 ppm, preferably from 30 ppm to 300 ppm or from 40 ppm to 200 ppm, more preferably from 50 ppm to 150 ppm, relative to the quantity of metal ore concentrate or dry matter of the composition to be concentrated; or for which: • the polymer P has an average molecular mass Mw, measured by CES, ranging from 2,000 g / mol to 20,000 g / mol, preferably from 2,200 g / mol to 10,000 g / mol or from 2,400 g / mol to 9,500 g / mol or from 2,400 g / mol to 8,000 g / mol, more preferably from 2,400 g / mol to 6,500 g / mol; or for which: • the polymerization reaction is also carried out in the presence of at least one compound comprising phosphorus in oxidation state I, preferably a compound chosen from hypophosphorous acid (H3PO2) and a derivative of hypophosphorous acid (H3PO2), preferably a compound comprising at least one hypophosphite ion (H2PO2), more preferably a compound chosen from sodium hypophosphite (EhPChNa), potassium hypophosphite (H2PO2K), calcium hypophosphite ([EhPChkCa) and mixtures thereof; or • the polymerization reaction is also carried out in the presence of at least one compound comprising phosphorus in oxidation state III, preferably a compound chosen from phosphorous acid and a phosphorous acid derivative, more preferably a compound comprising at least one phosphite ion, in particular a compound chosen from sodium phosphite, calcium phosphite, potassium phosphite, ammonium phosphite and combinations thereof; or • the polymerization reaction is also carried out in the presence of at least one compound comprising a bisulfite ion, preferably a compound chosen from ammonium bisulfite, an alkali metal bisulfite, in particular sodium bisulfite, potassium bisulfite, calcium bisulfite, magnesium bisulfite and combinations thereof; or • the polymerization reaction is also carried out in the presence of 0.05 to 5% by weight, relative to the total quantity of monomers, of at least one compound chosen from a xanthate derivative, a mercaptan compound and a compound of formula (I): in which: X independently represents H, Na or K, R independently represents a C1-C8-alkyl group, preferably a methyl group; in particular a compound of formula (I) which is disodium trithiocarbonate diisopropionate (DPTTC); or • the polymer P is totally or partially neutralized, in particular at the end of the polymerization reaction; or • the polymerization reaction involves: 100% by weight of anionic monomer M or from 70% to 99.5% by weight of anionic monomer M and from 0.5% to 30% by weight of at least one other monomer.

7. Method according to one of claims 1 to 6 for which the anionic monomer M comprising at least one polymerizable olefinic unsaturation, comprises one or two carboxylic acid functions, preferably comprises a single carboxylic acid function, preferably it is chosen from acrylic acid, methacrylic acid, an acrylic acid salt, a methacrylic acid salt and mixtures thereof, more preferably acrylic acid; or for which the polymerization reaction also uses at least one other monomer chosen from: another anionic monomer, preferably a monomer chosen from acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride and mixtures thereof; 2-acrylamido-2-methylpropane sulfonic acid, a 2-acrylamido-2-methylpropane sulfonic acid salt, 2-(methacryloyloxy)ethanesulfonic acid salt 2-(methacryloyloxy)ethanesulfonic acid, sodium methallyl sulfonate, styrene sulfonate and combinations or mixtures thereof; a non-ionic monomer comprising at least one olefinic unsaturation polymerizable, preferably at least one polymerizable ethylenic unsaturation and in particular a polymerizable vinyl function, more preferably a non-ionic monomer chosen from styrene, vinylcaprolactam, esters of an acid comprising at least one monocarboxylic acid function, in particular an ester of an acid chosen from acrylic acid, methacrylic acid, and mixtures thereof, for example hydroxy ethylacrylate, hydroxypropylacrylate, hydroxy ethylmethacrylate, hydroxypropylmethacrylate, alkyl acrylate, in particular C1-C10-alkyl acrylate, preferably C1-C4-alkyl acrylate, more preferably methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, alkyl methacrylate, in particular C1-C10-alkyl methacrylate, preferably C1-C4-alkyl methacrylate, more preferably C1-C4-alkyl methacrylate methyl, ethyl methacrylate, n-propyl methacrylate,isopropyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, aryl acrylate, preferably phenylacrylate, benzylacrylate, phenoxy ethylacrylate, aryl methacrylate, preferably phenylmethacrylate, benzylmethacrylate, phenoxyethylmethacrylate; a monomer of formula (II):, in which: R 1 and R 2 , identical or different, independently represent H or CH3, L 1 independently represents a group chosen from C(O), CH2, CH2-CH2 and O-CH2-CH2-CH2-CH2, L 2 independently represents a group chosen from (CEh-CEhC x, (CH2CH(CH3)O) y , (CH(CH3)CH2O) Z and their combinations and x, y and z, identical or different, independently represent an integer or decimal number between 0 and 150 and the sum x+y+z is between 10 and 150.

8. Method according to one of claims 1 to 7 comprising the addition of one, two or three different polymers P or at least one additional compound chosen from a lignosulfonate derivative, a silicate, an unmodified polysaccharide and a modified polysaccharide.

9. Method for improving the filtration of an aqueous composition which comprises at least one metal ore concentrate, comprising the implementation of at least one concentration method defined according to one of claims 1 to 8.

10. Concentrated aqueous composition comprising at least one metal ore concentrate and an aqueous concentrating agent A comprising at least one polymer P which is prepared by at least one radical polymerization reaction, at a temperature above 50°C, of ​​at least one anionic monomer M comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts, in the presence of at least one radical-generating compound chosen from hydrogen peroxide, benzoyl peroxide, acetyl peroxide, lauryl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, ammonium persulfate, an alkali metal persulfate, an azo compound, such as 2,2'-azobis(2-(4,5-dihydroimidazolyl)propane, dihydrochloride 2,2'-azobis(2-methylpropionamidine), diazovalero-nitrile, acid 4,4'-azobis-(4-cyanovaleric), AZDN or 2,2'-azobisisobutyronitrile, and their respective combinations or associations with an ion selected from Fe 11 , Fe 111 , Cu 1 , Cu 11 and their mixtures or concentrated aqueous composition prepared according to the concentration method according to one of claims 1 to 8; preferably comprising a humidity level of less than 15% by weight, more preferably less than 14% by weight or less than 13% by weight, much more preferably less than 12% by weight or less than 11% by weight, measured by mass loss measurement.

11. Aqueous filter cake comprising at least one metal ore concentrate and an aqueous concentrating agent A comprising at least one polymer P which is prepared by at least one radical polymerization reaction, at a temperature above 50°C, of ​​at least one anionic monomer M comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts, in the presence of at least one radical-generating compound chosen from hydrogen peroxide, benzoyl peroxide, acetyl peroxide, lauryl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, ammonium persulfate, an alkali metal persulfate, an azo compound, such as 2,2'-azobis(2-(4,5-dihydroimidazolyl)propane, dihydrochloride 2,2'-azobis(2-methylpropionamidine), diazovalero-nitrile, acid 4,4'-azobis-(4-cyanovaleric), AZDN or 2,2'-azobisisobutyronitrile, and their respective combinations or associations with an ion selected from Fe 11 , Fe 111 , Cu 1 , Cu 11 and their mixtures or aqueous filtration cake prepared according to the concentration method according to one of claims 1 to 8; preferably comprising a humidity level of less than 15% by weight, more preferably less than 14% by weight or less than 13% by weight, much more preferably less than 12% by weight or less than 11% by weight, measured by mass loss measurement.

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