Process for recovering one or more valuable compounds by flotation

Abstract

The present invention relates to a process for recovering one or more valuable compounds by separating solid particles by flotation, this process comprising the addition of a water-soluble polymer having a specific composition.

Description

Title of the invention: Method for recovering one or more valuable compounds by flotation. Technical field of the invention

[0001] The present invention relates to a method for separating minerals by flotation comprising the addition of a water-soluble polymer. Prior state of the art

[0002] The industrial growth of the 20th century required considerable quantities of metals and prompted mining operators to turn to new sources of raw material, such as metallic deposits with low ore concentration or liberation lattice rocks requiring more extensive grinding and for which the classic enrichment methods based on the exploitation of the physical properties (density, magnetic susceptibility...) of minerals are not applicable.

[0003] Mining operators have thus had to develop new techniques for processing these ores, such as flotation, which relies on specific physical or chemical affinities between a hydrophobic compound and a mineral. The mineral can then be physically separated using bubbling. Furthermore, the affinity between the hydrophobic compound and the mineral can be adjusted to create selective hydrophobicization of certain minerals.

[0004] The principle of ore processing by flotation is as follows: an ore is crushed and then ground, generally in a wet process, to reach the fractional size at which valuable compounds are released, thus forming a mineral pulp. The mineral pulp is generally conditioned with pH or redox potential modifiers, as well as various surface-modifying agents such as depressants and collectors. These chemical reagents modulate the surface's physicochemical properties, thereby allowing the selective flotation of the particle of interest, whether it be valuable compounds such as a mineral containing valuable chemical elements or gangue (the worthless material contained in an ore). The conditioned mineral pulp is then introduced into a flotation apparatus into which air is injected to generate bubbles that, as they rise, collect the hydrophobic particles of interest.Generally, a foaming agent is also introduced to aid in the formation of small bubbles and stabilize them for better flotation of the hydrophobic particles of interest. This results in a supernatant foam laden with hydrophobic particles of interest, which is collected by passive overflow or mechanical scraping. The solid particles, whether they are in the supernatant foam or... whether they remain in the flotation cell after flotation, then generally undergo one or more liquid / solid separation steps including thickening and filtration.

[0005] Flotation can be adapted to a wide range of compounds. Indeed, depending on the choice of collector and pre-conditioning steps with other flotation reagents, it is possible to selectively hydrophobicize the surfaces of the material to be floated, which can include gangue (reverse flotation) or valuable compounds such as minerals containing valuable chemical elements such as metals (direct flotation).

[0006] However, flotation separation performance depends on numerous parameters (temperature, flotation pH, particle size, mineral proportions, air flow rate, pulp solids content, choice of flotation reagents, addition sequences and dosages of flotation reagents, etc.). Modifying one of these parameters impacts the others, and it is extremely difficult to study the effects of a single parameter in isolation and to offer universal treatments.

[0007] In the interest of industry and for the sake of environmental protection, it is necessary to develop new flotation processes that improve the quantity of particles of interest recovered. The Applicant has discovered that adding a water-soluble polymer with a specific monomeric composition between the addition of the collector and the air bubbling process improves the quantity of particles of interest recovered during flotation.

[0008] The process according to the invention is universal and, in particular, allows for improved recovery of fine or ultrafine particles, meeting the current constraints of the mining industry in which ores are being ground increasingly finely. The process of the invention also allows for an improvement in the flotation kinetics of fine and ultrafine particles.

[0009] Improving flotation kinetics allows for an increase in the processing capacity of flotation equipment already in place, and in the case of new projects, allows for a reduction in the equipment footprint in terms of size, ground footprint, air consumption and electricity consumption.

[0010] The process according to the invention is based on a principle of environmental awareness and an understanding of the impact of industry and humankind on the planet. The process of the invention makes it possible to reduce the environmental impact of extracting valuable compounds from the extractive industry (from mines and quarries) by reducing the amount of air and electricity consumed, thereby reducing the amount of greenhouse gases, such as carbon dioxide, released during the extraction of these valuable compounds.

[0011] Furthermore, the present invention is advantageously implemented using materials of biological origin, for example biomass, or recycled materials. The synthesis of the monomers used is advantageously a biological synthesis, for example, by enzymatic catalysis. The energy used to implement the flotation process according to the invention is advantageously derived from a heat pump or from renewable sources, for example wind power, photovoltaics, or, particularly for mobile installations, from fuel cells or lithium batteries. Description of the invention

[0012] The present invention relates to a flotation process for solid particles from mines and / or quarries, comprising the addition of a specific water-soluble polymer between the addition of the collector and the bubbling of air.

[0013] More specifically, the invention relates to a process for recovering one or more valuable compounds by flotation of solid ore particles comprising at least the following steps: (a) Addition and mixing of at least one collector to a mineral pulp in order to form a conditioned PCI pulp, the mineral pulp originating from a mine or quarry, the mineral pulp comprising water and particles of interest, the particles of interest being solid ore particles; b) Addition and mixing of at least one water-soluble polymer into the conditioned pulp PCI, in order to form a conditioned pulp PC2, the water-soluble polymer comprising at least: - a hydrophobic monomer A, representing between 0.1 and 50 mol% of the monomers of the water-soluble polymer; - a hydrophilic monomer B, representing between 50 and 99.9 mol% of the monomers of the water-soluble polymer and chosen from the group consisting of: * non-ionic hydrophilic monomers; * anionic hydrophilic monomers; and * their mixtures; c) Direct or reverse flotation by air bubbling in the conditioned pulp PC2 in order to obtain a loaded foam and a treated pulp Pt; d) Recovery of the charged foam and putting it into aqueous solution in order to obtain a Pf pulp; e) When step c) is a direct flotation, liquid / solid separation of the Pf pulp to obtain a SI solid containing one or more valuable compounds from the mineral pulp, or when step c) is a reverse flotation, liquid / solid separation of the treated pulp Pt in order to obtain a solid S2 containing one or more valuable compounds from the mineral pulp. Description of the invention

[0014] The term "solid ore particles" refers to any solid particles originating from the exploitation of primary mineral resources, as well as material particles from urban mines, known as secondary mineral resources. Therefore, solid particles originating from the exploitation of oil sands are excluded from the scope of the invention.

[0015] By "urban mines" we mean sites for the treatment of waste electrical and electronic equipment leading to the recovery of material particles, for example the "black mass" obtained during the recycling of lithium-ion batteries or the phosphors of compact fluorescent light bulbs.

[0016] The term “gangue” refers to any mineral species, crystalline or amorphous, and non-mineral materials, in particular plastics (in the case of waste electrical and electronic equipment) present in an ore but not recoverable.

[0017] The term "polymer" refers to a polymer prepared from at least two different monomers, at least one hydrophobic monomer A and at least one hydrophilic monomer B (selected from nonionic hydrophilic monomers and anionic hydrophilic monomers and mixtures thereof). This polymer may further comprise at least one other monomer selected from cationic hydrophilic monomers, zwitterionic hydrophilic monomers and mixtures thereof.

[0018] By "hydrophilic monomer" is meant a monomer which has an octanol / water partition coefficient, Kow, less than or equal to 1, in which the partition coefficient Kow is determined at 25 °C in an octanol / water mixture having a volume ratio of 1 / 1, at a pH between 6 and 8.

[0019] By "hydrophobic monomer" is meant a monomer which has an octanol / water partition coefficient, Kow, greater than 1, in which the partition coefficient Kow is determined at 25 °C in an octanol / water mixture having a volume ratio of 1 / 1, at a pH between 6 and 8.

[0020] The octanol / water partition coefficient, Kow, represents the ratio of the concentrations (g / L) of a monomer between the octanol phase and the aqueous phase. It is defined as follows:

[0021] [Math.l] [monomer!] j^r __ L ^octanol nm: — [monomer^

[0022] By "water-soluble polymer" is meant a polymer which gives an aqueous solution without insoluble particles when dissolved under stirring at 25°C and with a concentration of 10 gL 1 in deionized water.

[0023] By "X and / or Y" we mean "X", or "Y", or "X and Y", that is to say the group consisting of X, Y and their mixtures.

[0024] Also part of the invention are all possible combinations of the various disclosed embodiments, whether preferred or given by way of example. Furthermore, where ranges of values ​​are indicated, the endpoints are included in those ranges. The disclosure also includes all combinations of the endpoints of those ranges of values. For example, the ranges of values ​​"1-20, preferably 5-15" imply the disclosure of the ranges "1-20", "1-5", "1-15", "5-20", and "15-20", and the values ​​1, 5, 15, and 20. Flotation process

[0025] The term "particle of interest" refers to the solid particle that it is desirable to float. In other words, it may be valuable compounds in the case of direct flotation, such as a mineral contained in an ore, or it may be gangue in the case of reverse flotation.

[0026] Mineral pulp is advantageously obtained following the mixing of solid particles from mines and / or quarries. It is generally obtained, but not necessarily, after a crushing step followed by a grinding step, advantageously using a wet process. In the case of urban mines, the grinding step corresponds to the shredding step. These steps aim to reduce the size of the solid particles to achieve the mesh size required for the release of the valuable compound(s).

[0027] Comminution can be carried out using any type of apparatus known to those skilled in the art that allows for the fragmentation of the ore. Examples include: a jaw crusher, a cone crusher, a ball mill, or a (semi-)autogenous mill.

[0028] The particles of interest are generally obtained after the various comminution steps.

[0029] Thus, the particles of interest in step a) advantageously have a D80 between 10 and 150 pm, preferably a D80 between 10 and 63 pm, preferably a D80 between 10 and 44 pm, and more preferably between 10 and 25 pm. Ores with a D80 below 10 pm are considered by those skilled in the art to be unsuitable for flotation processing. "D80 between 10 and 150 pm" means that 80% of the particles of interest have a value between 10 pm and 150 pm.

[0030] The term "microparticle size" refers to the average size, by number, of the microparticles. It corresponds to the largest dimension, for example, the diameter for spherical particles, preferably measured with a laser measuring device using conventional techniques that are part of the knowledge of those skilled in the art. A Mastersizer-type device from Malvern, for example the MS2000, can be used for this purpose. This type of device makes it possible to measure, by laser diffraction, the granular distribution of particles in a liquid medium or in solid form, preferably in a multiphase suspension.

[0031] In a preferred mode, the particle or particles of interest is a valuable compound. Thus, the particle or particles of interest in step a) are advantageously chosen from the group consisting of: an iron ore, a copper ore, a cobalt ore, a lead ore, a zinc ore, a lithium ore, a phosphate ore, a gold ore, a platinum group ore, a molybdenum ore, a nickel ore, a tin ore, a tungsten ore, an ore of at least one rare earth element, a tantalum ore, a niobium ore, a titanium ore, a zirconium ore, a fluorite ore, a barite ore, a potash ore, polymetallic ores, and mixtures thereof. Preferably, it is an iron ore, a copper ore, a gold ore, a platinum group ore, associated polymetallic ores, or a mixture thereof. More preferably, it is an iron ore.

[0032] Thus, the valuable compound is advantageously chosen from the group consisting of: iron compounds, copper compounds, cobalt compounds, lead compounds, zinc compounds, lithium compounds, phosphate compounds, gold compounds, platinum compounds, molybdenum compounds, nickel compounds, tin compounds, tungsten compounds, rare earth compounds, tantalum compounds, niobium compounds, titanium compounds, zirconium compounds, fluorite compounds, barite compounds, potash compounds, polymetallic compounds, and mixtures thereof. Preferably, it is a compound of iron, copper, gold, platinum group metals, a polymetallic compound, or a mixture of at least two of these compounds. More preferably, it is an iron compound.

[0033] In a preferred mode, the valuable compounds do not originate from an urban mine.

[0034] In a preferred mode, the valuable compounds are not particles of sulfide minerals.

[0035] Step a)

[0036] In step a), at least one collector is added and mixed with a mineral pulp.

[0037] The mineral pulp comprises solid particles, advantageously between 20 and 60% by weight relative to the total weight of the mineral pulp, preferably between 30 and 50% by weight.

[0038] During step a), a collector is added.

[0039] The role of the collector is to hydrophobicize the particles of interest. The general knowledge of a person skilled in the art allows them to choose the collector, as well as the optional flotation agents (activators, depressants, pH and redox potential modifiers, etc.), according to the nature of the particles of interest.

[0040] Collectors can be classified according to their ionic charge. In general, the ionic charge manifests itself according to the dissociation state of the collector, which can vary depending on the pH. Collectors can be non-ionic (i.e., non-dissociable), anionic, or cationic.

[0041] In a particular mode, the collector is non-ionic.

[0042] Examples of non-ionic collectors are advantageously, but not limited to, alcohols (preferably methanol, ethanol or butanol), glycols, polyglycols (advantageously polyethylene glycol or polypropylene glycol), polyols (advantageously glycerol), hydrocarbons (advantageously kerosene), paraffin-rich oils, or naphthene-rich oils.

[0043] In a preferred mode, the collector is not non-ionic.

[0044] In a particular mode, the collector is anionic.

[0045] Examples of anionic collectors include, for example and without limitation, compounds bearing thiol functions (advantageously xanthates, dithiophosphates, dithiocarbamates, or dithiocarbamates); collectors bearing carboxylic acid, sulfonic, phosphonic, sulfosuccinate, or sulfosuccinamate functions and their salts; or fatty acids advantageously in C8 to C30.

[0046] In a preferred mode, the collector is cationic.

[0047] Examples of cationic collectors include, for example and without limitation, compounds bearing ammonium functions (-NR3+, with R being able to independently represent a hydrogen atom or a Ci-C6 hydrocarbon chain), amine ethers, mercaptobenaothiazole salts, or cationic dithiophosphates.

[0048] The quantity of collector added to the pulp, during step a), is advantageously between 10 and 500 g / t relative to the total quantity of solid particles in the mineral pulp, preferably between 10 and 100 g / t, more preferably between 20 and 50 g / t by weight.

[0049] Once the collector has been added and mixed, a conditioned PCI pulp is obtained.

[0050] In a particular mode, the method of the invention includes the addition of at least one depressant and / or at least one activator upstream of the addition of the collector.

[0051] These products are used to modify mineral surfaces and affect the affinity between the collector and certain mineral surfaces, improving the selectivity of the collector with respect to particles of interest.

[0052] Examples of depressants include sodium silicate for silicates; starch and its derivatives for iron oxides; lime for pyrite; sodium cyanide or zinc sulfate for sphalerite; and hydrofluoric acid for feldspars. By extension, pH regulators can also be considered depressants.

[0053] Examples of activators include copper sulfate for reactivating the previously depressed surface of sphalerite; sodium hydrogen sulfide for copper oxides; and soluble metal salts. By extension, pH regulators can also be considered activators in certain cases.

[0054] All of these compounds are known to a person skilled in the art and he will be able to select them according to the type of particles of interest he wishes to float.

[0055] A person skilled in the art will know how to adjust the quantity of depressant and / or activator according to the ore.

[0056] Step b)

[0057] In step b), at least one water-soluble polymer is added and mixed with the conditioned pulp PCI. This addition allows the conditioned pulp PC2 to be formed.

[0058] The addition of the water-soluble polymer can be done in one step or in several steps (advantageously separated by a mixing step). Preferably, the addition is done in one step.

[0059] The water-soluble polymer comprises at least: - a hydrophobic monomer A representing between 0.1 and 50 mol% of the water-soluble polymer; - a hydrophilic monomer B, representing between 50 and 99.9 mol% of the monomers of the water-soluble polymer and chosen from the group consisting of: * non-ionic hydrophilic monomers; * anionic hydrophilic monomers; and * their mixtures.

[0060] The hydrophobic monomer A may comprise one or more halogens, for example chlorine.

[0061] The hydrophobic monomer A of the water-soluble polymer added in step b) is advantageously chosen from the group consisting of: (meth)acrylic acid esters having a (i) C4-C30 alkyl chain, or (ii) an arylalkyl chain having a C4-C30 alkyl and a C4-C30 aryl, or (iii) a propoxylated chain, or (iv) an ethoxylated chain, or (v) ethoxylated and propoxylated; alkyl aryl sulfonates having a C4-C30 alkyl and a C4-C30 aryl; mono-substituted (meth)acrylamide amides having a (i) C4-C30 alkyl chain, or (ii) an arylalkyl chain having a C4-C30 alkyl and a C4-C30 aryl, or (üi) a propoxylated chain, or (iv) an ethoxylated chain, or (v) an ethoxylated and propoxylated chain; di-substituted (meth)acrylamide amides having two chains selected from (i) a C4-C30 alkyl chain, or (ii) an arylalkyl chain having a C4-C30 alkyl and a C4-C30 aryl, or (iii) a propoxylated chain, or (iv) an ethoxylated chain, or (v) an ethoxylated and propoxylated chain; anionic or cationic monomeric derivatives of (meth)acrylamide bearing a hydrophobic chain; anionic or cationic monomeric derivatives of (meth)acrylic acid bearing a hydrophobic chain; vinylpyridine; and mixtures thereof.

[0062] Among these hydrophobic monomers A: - Alkyl groups are in C4-C2O, preferably C4-C8. Alkyls in C6-C2O are preferably linear alkyls, while alkyls in C4-C5 are preferably branched. - arylalkyl groups are preferably in C7-C25, more preferably in C7-C 15, - ethoxylated chains advantageously comprise between 1 and 200 -CH2-CH2-O- groups, preferably between 6 and 100, more preferably between 10 and 40, - propoxylated chains advantageously comprise between 1 and 50 -CH2-CH2-CH2-O- groups, more preferably between 1 and 20.

[0063] Preferred hydrophobic monomers A belonging to these classes are, advantageously: - n-hexyl (meth)acrylate, n-octyl (meth)acrylate, octyl (meth)acrylamide, lauryl (meth)acrylate, lauryl (meth)acrylamide, myristyle (meth)acrylate, myristyle (meth)acrylamide, pentadecyl (meth)acrylate, pentadecyl (meth)acrylamide, cetyl (meth)acrylate, cetyl (meth)acrylamide, oleyl (meth)acrylate, oleyl (meth)acrylamide, erucyl (meth)acrylate, erucyl (meth)acrylamide, N-tert-butyl(meth)acrylamide, vinylpyridine, 2-ethylhexyl acrylate, C4-C22 itaconic acid hemi-esters, acidified or quaternized salts of C4-C22 dialkyl aminoalkyl (meth)acrylate, acidified or quaternized salts of C4-C22 dialkyl-aminoalkyl (meth)acrylamides, acrylamidoundecanoic acid, and mixtures thereof, - cationic allyl derivatives of formula (I) or (II):

[0064] [Chem.l]

[0065] in which: R: independently an alkyl chain containing 1 to 4 carbons; Ri: an alkyl or arylalkyl chain comprising 8 to 30 carbons; X: a halide chosen from the group consisting of bromides, chlorides, iodides, fluorides, and any negatively charged counterion; and - preferably, cationic derivatives of the (meth)acryloyl type corresponding to formula (III):

[0066] [Chem.2]

[0067] in which: * A represents O or N-R5 (preferably A represents N-R5), * R2, R3, R4, R5, R6, R?: independently a hydrogen atom or an alkyl chain containing 1 to 4 carbons, * Q: an alkyl chain comprising 1 to 20 carbons, * R8: an alkyl or arylalkyl chain comprising 8 to 30 carbons, * X: a halide chosen from the group consisting of bromides, chlorides, iodides, fluorides, and any negatively charged counterion.

[0068] A particularly preferred hydrophobic monomer A is 1-dodecanaminonium, N,N-dimethyl-N-[3-[(2-methyl-l-oxo-2-propene-l-yl)amino]propyl]-, bromide.

[0069] The quantity of hydrophobic monomers A represents between 0.1 and 50 mol% of the monomers of the water-soluble polymer, preferably between 1 and 45 mol%, plus preferentially between 2 and 40, more preferentially between 3 and 30 mol%, more preferentially between 5 and 25 mol%, and even more preferentially between 10 and 20 mol%.

[0070] A person skilled in the art will know how to adjust the quantity of hydrophobic monomers A according to the hydrophobicity of the latter and possibly the quantity of hydrophilic monomers C (the monomers C being cationic and / or zwitterionic as specified below), so that the water-soluble polymer remains soluble in water.

[0071] Advantageously, the non-ionic hydrophilic monomer(s) B of the water-soluble polymer added in step b) are selected from the group consisting of: acrylamide, methacrylamide, N-alkylacrylamides, N-alkylmethacrylamide, N,N-dialkylacrylamides (for example, N,N-dimethylacrylamide or N,N-diethylacrylamide), N,N-dialkylmethacrylamides, alkoxylated esters of acrylic acid, alkoxylated esters of methacrylic acid, N-vinylpyrrolidone, N-methylol(meth)acrylamide, N-vinyl caprolactam, N-vinylformamide (NVF), N-vinyl acetamide, N-vinyl imidazole, N-vinyl succinimide, acryloyl morpholine (ACMO), glycidyl methacrylate, vinyl acetate, glyceryl methacrylate, diacetone acrylamide, methacrylic anhydride, acrylonitrile, maleic anhydride, itaconic anhydride, itaconamide, hydroxyalkyl (meth)acrylate, thioalkyl (meth)acrylate, isoprenol, alkoxylated derivatives of isoprenol,Hydroxyethyl(meth)acrylates; alkoxylated derivatives of hydroxyethyl(meth)acrylates, hydroxypropyl(meth)acrylate, alkoxylated derivatives of hydroxypropyl(meth)acrylate, and mixtures thereof. Among these nonionic monomers, the alkyl groups are advantageously in the C1-C5 position, more advantageously in the C1-C3 position. The C3-C5 alkyl groups are advantageously branched. Preferably, the nonionic hydrophilic monomer B is acrylamide.

[0072] The hydrophilic anionic monomer(s) B used in the context of the invention may be selected from a wide range of sources. These monomers may have a vinyl functional group, in particular acrylic, maleic, fumaric, malonic, itaconic, or allylic. They may also contain a carboxylate, phosphonate, phosphate, sulfonate, sulfate, or other anionically charged group.Advantageously, the hydrophilic anionic monomer(s) B used in the context of the invention are selected from: acrylic acid; methacrylic acid; dimethylacrylic acid; acryloyl chloride; crotonic acid; maleic acid; fumaric acid; 3-acrylamido 3-methylbutanoic acid; strong acid-type monomers having, for example, a sulfonic acid or phosphonic acid function such as vinylsulfonic acid, vinylphosphonic acid, allylsulfonic acid, methallylsulfonic acid, 2-methylidenepropane-1,3-disulfonic acid, 2-sulfoethyl methacrylate, sulfopropyl methacrylate, the . Sulfopropylacrylate, allylphosphonic acid, ethylene glycol methacrylate phosphate, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid (ATBS), 2-acrylamido-2-methylpropane disulfonic acid, 3-allyloxy-2-hydroxypropane sulfonic acid, diethylallylphosphonate, carboxyethyl acrylate; water-soluble salts of these monomers such as their alkali metal, alkaline earth metal, or ammonium salts; and mixtures thereof. Preferably, the hydrophilic anionic monomer B is acrylic acid or 2-acrylamido-2-methylpropane sulfonic acid (ATBS).

[0073] In a particular mode, when the anionic hydrophilic monomer B is 2-acrylamido-2-methylpropanesulfonic acid (ATBS), it is in its hydrated form. The hydrated form of ATBS is a particular form of ATBS obtained by controlled crystallization of the ATBS monomer. US Patent 10,759,746 describes this hydrated form of ATBS.

[0074] In a particular embodiment of the invention, the hydrophilic anionic monomer(s) B may be salified. It may also be a mixture of the acidic and salified forms, for example, a mixture of acrylic acid and acrylate. Salified means the substitution of a proton of at least one acidic functional group of the type -Ra(=O)-OH (with Ra representing P, S, or C) of the anionic monomer by a metal or organic cation to form a salt of the type -Ra(=O)-0 A+ (A+ being a metal or organic cation). In other words, the unsalified form corresponds to the acidic form of the monomer, for example, Rb-C(=O)-OH in the case of the carboxylic acid functional group, whereas the salified form of the monomer corresponds to the form Rb-C(=O)-0 A+, A+ being a metal or organic cation. The salification of the acidic functional groups may be partial or complete.

[0075] The metal cation is advantageously an alkali metal ion (Li+, Na+, K+ ...) or an alkaline earth metal ion (Ca2+, Mg2+...), and the organic cation is advantageously the ammonium ion or a tertiary ammonium compound. Preferred salts are sodium salts.

[0076] Salification can take place before or after polymerization.

[0077] The quantity of hydrophilic monomers B represents between 50 and 99.9 mol% of the monomers of the water-soluble polymer, preferably between 55 and 99 mol%, more preferably between 60 and 98 mol%, more preferably between 70 and 97 mol%, more preferably between 75 and 95 mol%, and even more preferably between 80 and 90 mol%.

[0078] In a preferred mode, the hydrophilic monomer B is a non-ionic hydrophilic monomer.

[0079] The water-soluble polymer may further comprise at least one hydrophilic monomer C selected from: anionic hydrophilic monomers, cationic hydrophilic monomers, zwitterionic hydrophilic monomers and mixtures thereof,

[0080] In a preferred mode, the hydrophilic monomer C is at least one cationic hydrophilic monomer.

[0081] The cationic hydrophilic monomer(s) C used in the context of the invention are chosen, in particular, from vinyl-type monomers, especially acrylamide, acrylic, allylic, or maleic monomers having a protonable amine or ammonium function, advantageously a quaternary ammonium. Advantageously, the cationic hydrophilic monomer(s) C used in the context of the invention are chosen from: diallyldialkyl ammonium salts such as dimethyldiallylammonium chloride (DADMAC); acidified or quaternized dialkyl-aminoalkyl(meth)acrylamides, such as (3-methacrylamidopropyl)trimethylammonium chloride (MAPTAC), (3-acrylamidopropyl)trimethylammonium chloride (APTAC); acidified or quatemized dialkyl-aminoalkyl acrylate salts such as quatemized or salified dimethylaminoethyl acrylate (ADAME);acidified or quaternized salts of dialkyl aminoalkyl methacrylate such as quaternized or salified dimethylaminoethyl methacrylate (MADAME); acidified or quaternized salts of N,N-dimethylallylamine; acidified or quaternized salts of diallylmethylamine; acidified or quaternized salts of diallylamine; acidified or quaternized salts of vinylamine obtained by the (basic or acidic) hydrolysis of an amide group -N(R2)-CO-R' with R1 and R2 being, independently, a hydrogen atom or an alkyl chain of 1 to 6 carbons, for example acidified or quaternized salts of vinylamine resulting from the hydrolysis of vinylformamide; acidified or quaternized salts of vinylamine obtained by Hofmann degradation;and mixtures thereof. Advantageously, the alkyl groups are in C1-C7, preferably in C1-C3, and may be linear, cyclic, saturated, or unsaturated chains. Preferably, the cationic hydrophilic monomer C is chosen from acidified or quaternized salts of dimethylaminoethyl (meth)acrylate, (3-(meth)acrylamidopropyl)trimethylammonium chloride, and mixtures thereof.

[0082] A particularly preferred cationic hydrophilic monomer C is dimethylaminoethyl benzyl chloride acrylate.

[0083] A person skilled in the art will know how to prepare the quaternized monomers, for example by means of quaternizing agent of type RX, R being an alkyl group and X being a halogen or a sulfate.

[0084] By “quaternizing agent” is meant a molecule capable of alkylating a tertiary amine.

[0085] The quaternizing agent can be selected from dialkyl sulfates comprising 1 to 6 carbon atoms or alkyl halides comprising 1 to 6 carbon atoms. Preferably, the quaternizing agent is selected from methyl chloride, benzyl chloride, dimethyl sulfate, or diethyl sulfate. Furthermore, the present invention also covers DADMAC, APTAC, and MAPTAC type monomers in which the counterion is a sulfate, a fluoride, a bromide, or an iodide instead of a chloride.

[0086] The hydrophilic zwitterionic monomer(s) used in the context of the invention are chosen, in particular, from derivatives of a vinyl type motif (advantageously acrylamide, acrylic, allyl or maleic), this monomer having a quaternary amine or ammonium function and an acid function of the carboxylic (or carboxylate), sulfonic (or sulfonate) or phosphoric (or phosphate) type.

[0087] Preferably, this monomer comprises a quaternary amine or ammonium function and an acid function of the carboxylic (or carboxylate), sulfonic (or sulfonate) type or phosphoric (or phosphate).

[0088] Advantageously, the hydrophilic zwitterionic monomer(s) used in the context of the invention are selected from: dimethylaminoethyl acrylate derivatives, such as 2-((2-9(acryloyloxy)ethyl)dimethylammonio)ethane-1-sulfonate, may be mentioned in particular and in a non-limiting manner, 3-((2-(acryloyloxy)ethyl)dimethylammonio)propane-1-sulfonate, 4-((2-(acryloyloxy)ethyl)dimethylammonio)butane-1-sulfonate, [2-(acryloyloxy)ethyl](dimethylammonio)acetate, dimethylaminoethyl methacrylate derivatives such as 2-((2-(methacryloyloxy)ethyl)dimethylammonio)ethane-1-sulfonate, 3-((2-(methacryloyloxy) ethyl) dimethylammonio) propane-1-sulfonate, 4-((2-(methacryloyloxy) ethyl) dimethylammonio) butane-1-sulfonate, [2-(methacryloyloxy) ethyl] (dimethylammonio) acetate, propylacrylamide dimethylamino derivatives such as 2-((3-acrylamidopropyl) dimethylammonio) ethane-1-sulfonate,3-((3-acrylamidopropyl)dimethylammonio)propane-1-sulfonate, 4-((3-acrylamidopropyl)dimethylammonio)butane-1-sulfonate, [3-(acryloyl)oxy)propyl](dimethylammonio)acetate, dimethylaminopropyl methylacrylamide, or derivatives such as 2-((3-methacrylamidopropyl)dimethylammonio)ethane-1-sulfonate, 3-((3-me dimethylammonio)propane-1-sulfonate, 4-((3-methacrylamidopropyl)dimethylammonio)butane-1-sulfonate and propyl [3-(methacryloyloxy)](dimethylammonio)acetate and mixtures thereof.

[0089] Other zwitterionic monomers are described by the Applicant in document WO2021 / 123599 Al.

[0090] The quantity of hydrophilic monomers C (cationic and / or zwitterionic) represents between 0 and 49.9 mol% of the monomers (A+B+C) of the water-soluble polymer, preferably between 0.1 and 25 mol%, preferably between 0.1 and 15 mol%, more preferably between 0.1 and 5 mol%.

[0091] The quantities of the different monomers A, B and optionally C will be adjusted by a person skilled in the art to achieve 100% molar of the water-soluble polymer.

[0092] The water-soluble polymer can have a linear, branched, ramified, star-shaped, or comb-shaped structure. Preferably, it is linear. This structure can be obtained, according to the general knowledge of a person skilled in the art, for example by selecting the initiator, the transfer agent, the polymerization technique such as reversible addition-fragmentation chain transfer polymerization (RAFT), nitroxide-mediated polymerization (NMP), or atom transfer radical polymerization (ATRP), by incorporating structural monomers, or by adjusting the concentration.

[0093] The water-soluble polymer can be structured by a branching agent. A structured polymer is defined as a non-linear polymer that has side chains.

[0094] The branching agent is advantageously chosen from: - Structuring agents, which may be chosen from the group comprising polyethylenic unsaturated compounds (having at least two unsaturated functions, with the exception of diallyldialkyl ammonium type compounds), such as vinyl functions, particularly allylic or acrylic, and examples include methylene bisacrylamide (MBA), triallyamine, or tetraallylammonium chloride or 1,2-dihydroxyethylene bis-(N-acrylamide), - compounds having at least two epoxy functions, - Compounds having at least one unsaturated function and one epoxy function, - Macroinitiators such as polyperoxides, polyazo compounds, and polytransfer agents such as polymer-capturing polymers and polyols, - Functionalized polysaccharides, - water-soluble metal complexes composed of: * of a metal with a valence greater than 3 such as, by way of example and without limitation, aluminium, boron, zirconium or titanium, and * of a ligand bearing a hydroxyl function.

[0095] When the water-soluble polymer includes at least one branching agent, it remains soluble in water. A person skilled in the art will know how to adjust the amount of branching agent, and possibly the amount of transfer agent, to achieve this result.

[0096] In a particular mode, the water-soluble polymer may include a transfer agent.

[0097] The transfer agent is advantageously selected from methanol; isopropyl alcohol; sodium hypophosphite; calcium hypophosphite; magnesium hypophosphite; potassium hypophosphite; ammonium hypophosphite; formic acid; sodium formate; calcium formate; magnesium formate; potassium formate; ammonium formate; 2-mercaptoethanol; 3-mercaptopropanol; dithiopropylene glycol; thioglycerol; thioglycolic acid; thiohydracrylic acid; thiolactic acid; thiomalic acid; cysteine; and aminoethanethiol; thioglycolates; allyl phosphites; allyl mercaptans; sodium methallysulfonate; Calcium methallysulfonate; magnesium methallysulfonate; potassium methallysulfonate; ammonium methallysulfonate; polythiols and mixtures thereof. Preferably, sodium hypophosphite or sodium formate.

[0098] The amount of transfer agent in the water-soluble polymer is advantageously between 10 and 20,000 ppm relative to the total weight of the monomers (A, B and possibly C) of the polymer, preferably between 100 and 10,000 ppm, more preferably between 500 and 5,000 ppm.

[0099] The water-soluble polymer advantageously has a molecular weight by weight of at least 0.5 million g / mol, preferably between 0.5 and 20 million g / mol, more preferably between 0.8 and 10 million g / mol, more preferably between 1 and 5 million g / mol.

[0100] The weight average molecular weight is preferably measured by Gel Permeation Chromatography coupled with a Malls detector.

[0101] In general, the water-soluble polymer can be obtained using all polymerization techniques well known to those skilled in the art. These may include, in particular, solution polymerization; gel polymerization; precipitation polymerization; emulsion polymerization (aqueous or reverse); suspension polymerization; reactive extrusion polymerization; water-in-water polymerization; or micellar polymerization. Preferably, it is solution or powder polymerization.

[0102] Polymerization is generally a free radical polymerization. By free radical polymerization, we include free radical polymerization by means of UV, azo, redox or thermal initiators as well as controlled radical polymerization (PCR) techniques or matrix polymerization techniques.

[0103] The quantity of initiator is advantageously between 100 and 10,000 ppm relative to the weight of all the monomers (A, B and possibly C) of the water-soluble polymer, preferably between 500 and 5,000 ppm.

[0104] The quantity of water-soluble polymer added to the conditioned PCI pulp is advantageously between 1 and 1,000 g / t (grams per metric ton of solid particles contained in the conditioned PCI pulp), preferably between 1 and 500 g / t by weight, more preferably between 1 and 100 g / t by weight.

[0105] In a particular mode, the hydrophilic monomer B is non-ionic and the water-soluble polymer comprises between 0.1 and 25 mol% of cationic monomer, preferably between 0.1 and 15 mol% of cationic monomer, more preferably between 0.1 and 5 mol% of cationic monomer.

[0106] The cationic monomer can be chosen from the set of monomers described above; it can be hydrophobic monomer(s) A or hydrophilic monomer(s) C. Preferably, it is monomer(s) chosen from monomer(s) A.

[0107] Once the water-soluble polymer has been added and mixed, a conditioned pulp PC2 is obtained.

[0108] The addition of the polymer is advantageously preceded or followed by the addition of a foaming agent.

[0109] The foaming agent can be chosen from aliphatic alcohols, cyclic alcohols (especially pine oil), aromatic alcohols (especially cresols), polyglycols, and mixtures thereof.

[0110] The quantity of foaming agent added to the conditioned pulp (PCI or PC2 depending on the order of addition) is advantageously between 0 and 1,000 g / t relative to the total weight of solid particles contained in the conditioned pulp (PCI or PC2 depending on the order of addition), preferably between 1 and 500 g / t, more preferably between 2 and 100 g / t and even more preferably between 5 and 50 g / t. [YES] Step c)

[0112] The bubbling of the conditioned PC2 pulp is advantageously carried out in a flotation cell. The flotation cell can be mechanical (for example, like Wemco-type cells), or it can be pneumatic (for example, like flotation columns and intensive flotation cells, particularly of the Jameson type). or Imhoflot™ or Concorde Cell™). Preferably, it is a mechanical flotation cell.

[0113] The term “flotation cell” refers to both mechanical and pneumatic cells, the two terms being interchangeable.

[0114] The gas used may be air, oxygen, hydrogen, nitrogen, carbon dioxide or a mixture of several of these gases. Preferably, it is air.

[0115] The bubbling of the conditioned pulp PC2 allows the hydrophobicized flocs of particles of interest (thanks to the addition of the polymer during step a)) to rise to the top of the flotation cell to accumulate them within a loaded foam which is then recovered during step d).

[0116] Advantageously, the flotation in step c) is a direct flotation.

[0117] Step d)

[0118] The loaded foam is recovered, for example by overflow or mechanical scraping, and returned to aqueous solution in order to obtain a Pf pulp.

[0119] Regardless of the type of flotation, the Pf pulp is enriched in particles of interest while the Pt pulp is depleted in particles of interest, the term particles of interest referring to the solid particles that it is desirable to float, whether they are valuable compounds or gangue.

[0120] Depending on the type of flotation, the pulp Pf comprises a majority of at least one particle of interest, whether it be a valuable compound and / or gangue. Similarly, depending on the type of flotation, the treated pulp Pt may comprise a majority of another valuable compound and / or gangue.

[0121] In the case of direct flotation, the Pf pulp advantageously comprises at least 50% by weight of particles of interest relative to the total weight of particles present in the Pf pulp, while the Pt pulp advantageously comprises at least 50% by weight of gangue and possibly other valuable compounds relative to the total weight of particles present in the Pt pulp.

[0122] In the case of reverse flotation, the Pf pulp advantageously comprises at least 50% by weight of gangue and possibly other valuable compounds relative to the total weight of particles present in the Pf pulp, while the Pt pulp advantageously comprises at least 50% by weight of particles of interest relative to the total weight of particles present in the Pt pulp.

[0123] Step e)

[0124] If step c) is a direct flotation, step e) consists of a liquid / solid separation of the pulp Pf in order to obtain a solid SI containing one or more valuable compounds from the mineral pulp.

[0125] If step c) is reverse flotation, a liquid / solid separation of the treated pulp Pt is carried out in order to obtain a solid S2 containing one or more valuable compounds from the mineral pulp.

[0126] Liquid / solid separation can be carried out by any means known to those skilled in the art. Examples include separation by decantation, filtration, or centrifugation. Preferably, liquid / solid separation is carried out by decantation followed by filtration.

[0127] Liquid / solid separation by decantation can be carried out using any type of decanter known to those skilled in the art. Examples include conventional decanters, high-flow decanters, high-density decanters, and paste decanters. Preferably, decantation is carried out using conventional decanters or a high-flow decanter.

[0128] Liquid / solid separation by filtration can be carried out using any type of equipment known to those skilled in the art. Examples include filter press filtration, belt filter filtration, and disc filter filtration. Preferably, filter press or disc filter filtration is used.

[0129] The process according to the invention may further comprise n (n being an integer between 1 and 5) consecutive sequences of steps a) to d) before step e), in order to recover all the valuable compounds from the mineral pulp.

[0130] In a particular mode, it is possible to use SI or S2 to form a mineral pulp that can be used in a second flotation process according to the process of the invention. The SI' and S2' resulting from this second flotation process can in turn be used in a third flotation process according to the process of the invention, and so on, until all the particles of interest have been extracted from the solid ore particles.

[0131] The polymer of the invention can also be used to improve the performance of other wet mineral processing techniques, i.e., mineral separation, and particularly the magnetic separation of fine ores. In these techniques, the water-soluble polymer can also be used in combination with depressants, activators, and optional collectors.

[0132] The water-soluble polymer used in the invention is advantageously of biological or recycled origin. Advantageously, it has a bio-based carbon content of between 5% by weight and 100% by weight relative to the total weight of carbon in the water-soluble polymer, the bio-based carbon content being measured according to ASTM D6866-21, method B.

[0133] The energy used to implement the flotation process according to the invention is advantageously derived from a heat pump or from renewable sources, advantageously of the wind, photovoltaic, fuel cell or lithium battery type.

[0134] The invention and its advantages will become clearer from the following figures and examples, which are given to illustrate the invention and not to limit it. Examples

[0135] List of abbreviations: SIBX: Sodium isobutyl xanthate AM: Acrylamide AA: Acrylic Acid EHA: 2-Ethylhexyl Acrylate Determination of molecular weight by GPC-Malls

[0136] Gel permeable chromatography (GPC) allows the separation of macromolecules according to their hydrodynamic volume. It is coupled to a Malls detector, allowing the measurement of light scattering at several angles.

[0137] The synthesized polymers are analyzed under the following conditions: - Instrument: Agilent 1260 Infinity system and Wyatt Technology detectors from Wyatt Technology. - Columns: Shodex™ SB-807-G Shodex™ SB-806-HQ Shodex™ SB-805 custom Shodex™ SB-803-HQ Shodex™ SB-802-HQ - Method: * Temperature: 25°C * Mobile phase: 0.4 M NaNO3, 100 ppm NaN3 + TFA (pH 3.5) (TFA = trifluoroacetic acid) * Injection: 100 pL * Flow rate: 0.5 mL / min * Analysis time: 110 min Model: Zimm order 1 GCP3 * Detection: (i) Dawn Heleos: Light scattering detector (MALS) (ii) Optilab T-Rex: Refractometry (RI) Determination of viscosity

[0138] Viscosity is measured using a Brookfield viscometer, at 25 °C with a Brookfield modulus selected from: LV4 speed 30 rpm, NaCl 1 M. Trial 1

[0139] Zinc flotation in a zinc mine

[0140] The flotation tests were carried out with a Denver brand laboratory flotation cell equipped with a 2.5 L tank for a volume of aqueous mineral pulp of approximately 2 L. The mineral pulp used for the tests was sampled from a zinc flotation processing plant. This mineral pulp contains an initial zinc content of 7.5% by weight. The pH of the pulp was adjusted to 11 with milk of lime (saturated aqueous solution of calcium hydroxide). After a mixing period of 8 minutes, SIBX (collector) is added to a dosage of 40 g / t of solid particles included in the mineral pulp, to form a conditioned PCI pulp (step a). After a mixing period of 2 minutes, a solution of a polymer (P1-P4) at 10 g per liter of water is added to the flotation cell at a dosage of 5 g / t of solid particles included in the mineral pulp to form a conditioned pulp PC2 (step b)). After a mixing period of 1 minute, a water-soluble foaming agent based on polyglycol is added at a dosage of 10 g / t of solid particles included in the mineral pulp. After a mixing period of 1 minute, air (bubbling of the conditioned pulp PC2; step c)) is introduced to start direct flotation in order to obtain a loaded foam and a Pf pulp. The total flotation time of zinc is 12 minutes. The charged foam is then recovered and put back into solution in water to form a Pf pulp (step d)). A liquid / solid separation of the pulp Pf is carried out to obtain a solid SI (step e)). The liquid / solid separation of the treated pulp Pt allows obtaining a solid S2. The particle size distribution of the SI solid exhibits a D80 of 32 pm.

[0141] Four polymers (P1-P4) were tested, their compositions are detailed in Table 1.

[0142] [Tables 1] Polymer Composition (mol%) Consistency (cps) Molecular Weight (g / mol) AM AA EHA Polymer PI (Counterexample) 85 15 - 4,600 238,000 Polymer P2 (Invention) 70 15 15 5,250 242,000 Polymer P3 (Counterexample) 30 15 55 5,500 NA Polymer P4 (Invention) 84.9 15 0.1 5,100 236,000

[0143] Table 1 - Composition and characteristics of polymers P1-P4

[0144] [Tables2] Polymer Tests Content Recovery Test 1-1 White 20.2% 85.1% Test 1-2 (Counterexample) PI 15.3% 84.3% Test 1-3 (Invention) P2 22.8% 91.5% Test 1-4 (Counterexample) P3 17.5% 85.5% Test 1-5 (Invention) P4 22.1% 88.2%

[0145] Table 2 - Results of flotation tests 1-1 to 1-5

[0146] The results obtained (Table 2) show that the polymers according to the invention (P2 and P4) generally improve zinc recovery (a valuable compound) with better selectivity (Zn content in SI) and a better recovery rate (% of Zn recovered in SI, compared to the initial amount of Zn in the mineral pulp). Test 2

[0147] The same protocol as that carried out in trial 1-3 is carried out, with the difference being the order of the sequences of addition of the flotation reagents.

[0148] The different orders and results are summarized in Table 3.

[0149] [Tables3] Test Addition sequence Content Recovery Test 2-1 (Blank) i) Collector ii) Bubble 20.2% 85.1% Test 2-2 (Inv) i) Collector ii) P2 iii) Bubble 22.5% 91.5% Test 2-3 (Cex) i) P2 ii) Collector iii) Bubble 17.5% 79.1% Test 2-4 (Cex) i) P2 + Collector ii) Bubble 18.1% 80.2%

[0150] Table 3 - Sequence of flotation steps and results of tests 2-1 to 2-4 (Cex: Counterexample, Inv: Invention)

[0151] The results obtained show that the addition sequence according to the invention is essential in the optimization of the flotation process, in terms of the proportion of ore recovered in the solid S1 and the yield in relation to the quantity of ore in the mineral pulp.

Claims

Demands

1. A process for recovering one or more valuable compounds by flotation of solid ore particles comprising at least the following steps: a) Adding and mixing at least one collector to a mineral pulp to form a conditioned pulp PCI, the mineral pulp originating from a mine or quarry, the mineral pulp comprising water and particles of interest, the particles of interest being solid ore particles; b) Adding and mixing at least one water-soluble polymer to the conditioned pulp PCI to form a conditioned pulp PC2, the water-soluble polymer comprising at least: - a hydrophobic monomer A, representing between 0.1 and 50 mol% of the monomers of the water-soluble polymer, - a hydrophilic monomer B, representing between 50 and 99.9 mol% of the monomers of the water-soluble polymer and selected from the group consisting of: * non-ionic hydrophilic monomers; * anionic hydrophilic monomers; and * mixtures thereof;c) Direct or reverse flotation by air bubbling in the conditioned pulp PC2 to obtain a charged foam and a treated pulp Pt; d) Recovery of the charged foam and dissolving it in aqueous solution to obtain a pulp Pf; e) When step c) is direct flotation, liquid / solid separation of the pulp Pf to obtain a solid SI containing one or more valuable compounds from the mineral pulp, or when step c) is reverse flotation, liquid / solid separation of the treated pulp Pt to obtain a solid S2 containing one or more valuable compounds from the mineral pulp.

2. A method according to claim 1, characterized in that the flotation in step c) is a reverse flotation.

3. A process according to claim 1 or 2, characterized in that the mineral pulp of step a) comprises between 20 and 60% by weight of solid particles, relative to the total weight of the mineral pulp.

4. A method according to any one of claims 1 to 3, characterized in that the particles of interest in step a) have a D80 between 10 and 150 pm.

5. A process according to any one of claims 1 to 4, characterized in that the particle or particles of interest in step a) are selected from the group consisting of: an iron ore, a copper ore, a cobalt ore, a lead ore, a zinc ore, a lithium ore, a phosphate ore, a gold ore, a platinum group ore, a molybdenum ore, a nickel ore, a tin ore, a tungsten ore, an ore of at least one rare earth, a tantalum ore, a niobium ore, a titanium ore, a zirconium ore, a fluorite ore, a barite ore, a potash ore, polymetallic ores, and mixtures thereof.

6. A method according to any one of claims 1 to 5, characterized in that the collector of step a) is cationic.

7. A process according to any one of claims 1 to 6, characterized in that the quantity of collector added to the pulp, during step a), is between 10 and 500 g / t, relative to the total quantity of solid particles in the mineral pulp.

8. A process according to any one of claims 1 to 7, characterized in that the hydrophobic monomer A of the water-soluble polymer added in step b) is selected from the group consisting of: (meth)acrylic acid esters having a (i) C4-C30 alkyl chain, or (ii) an arylalkyl chain having a C4-C30 alkyl and a C4-C30 aryl, or (iii) a propoxylated chain, or (iv) an ethoxylated chain, or (v) an ethoxylated and propoxylated chain; alkyl aryl sulfonates having a C4-C30 alkyl and a C4-C30 aryl; mono-substituted (meth)acrylamide amides having a (i) C4-C30 alkyl chain, or (ii) an arylalkyl chain having a C4-C30 alkyl and a C4-C30 aryl, or (iii) a propoxylated chain, or (iv) an ethoxylated chain, or (v) an ethoxylated and propoxylated chain; di-substituted (meth)acrylamide amides having two chains selected from (i) a C4-C30 alkyl chain, or (ii) an arylalkyl chain having a C4-C30 alkyl and a C4-C30 aryl, or (iii) a propoxylated chain, or (iv) an ethoxylated chain, or (v) an ethoxylated and propoxylated chain;anionic or cationic monomeric derivatives of (meth)acrylamide bearing a hydrophobic chain; derivatives;

9.

10. anionic or cationic monomers of (meth)acrylic acid bearing a hydrophobic chain; vinylpyridine and mixtures thereof. A process according to any one of claims 1 to 8, characterized in that the hydrophilic monomer B of the water-soluble polymer added in step b) is non-ionic and is selected from the group consisting of acrylamide, methacrylamide, N-alkylacrylamides, N-alkylmethacrylamides, N,N-dialkylacrylamides, N,N-dialkylmethacrylamides, alkoxylated esters of acrylic acid, alkoxylated esters of methacrylic acid, N-vinylpyrrolidone, N-methylol(meth)acrylamide, N-vinyl caprolactam, N-vinylformamide, N-vinyl acetamide, N-vinyl imidazole, N-vinyl succinimide, acryloyl morpholine, glycidyl methacrylate, vinyl acetate, glyceryl methacrylate, diacetone acrylamide, methacrylic anhydride, acrylonitrile, maleic anhydride, itaconic anhydride, itaconamide, hydroxyalkyl (meth)acrylate,thioalkyl (meth)acrylate, isoprenol, alkoxylated derivatives of isoprenol, hydroxyethyl (meth)acrylates, alkoxylated derivatives of hydroxyethyl (meth)acrylates, hydroxypropyl (meth)acrylate, alkoxylated derivatives of hydroxypropyl (meth)acrylate, and mixtures thereof, A process according to any one of claims 1 to 9, characterized in that the hydrophilic monomer B of the water-soluble polymer added in step b) is anionic and is selected from the group consisting of: acrylic acid; methacrylic acid; dimethylacrylic acid; acryloyl chloride; crotonic acid; maleic acid; fumaric acid; 3-acrylamido 3-methylbutanoic acid;strong acid monomers having, for example, a sulfonic acid or phosphonic acid function such as vinylsulfonic acid, vinylphosphonic acid, allylsulfonic acid, methallylsulfonic acid, 2-methylidenepropane-1,3-disulfonic acid, 2-sulfoethyl methacrylate, sulfopropyl methacrylate, sulfopropyl acrylate, allylphosphonic acid, ethylene glycol methacrylate phosphate, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 2-acrylamido-2-methylpropane disulfonic acid, 3-allyloxy-2-hydroxypropane sulfonic acid, diethylallylphosphonate, carboxyethyl acrylate; water-soluble salts of these monomers such as their metal salts; alkalis, alkaline earth metals, or ammonium; and mixtures thereof.

11. A process according to any one of claims 1 to 10, characterized in that the hydrophilic monomer B is non-ionic and in that the water-soluble polymer comprises between 0.1 and 25 mol% of cationic monomer.

12. A process according to any one of claims 1 to 11, characterized in that the water-soluble polymer is of bio-based or recycled origin, and in that the water-soluble polymer has a bio-based carbon content of between 5% by weight and 100% by weight relative to the total weight of carbon in the water-soluble polymer, the bio-based carbon content being measured according to ASTM D6866-21, method

13. -D. A process according to any one of claims 1 to 12, characterized in that the energy used to carry out the flotation process comes from a heat pump or from renewable sources, advantageously of the wind, photovoltaic, fuel cell or lithium battery type.