Suspension of mineral material

Abstract

The present invention relates suspension of at least one mineral material in water in the presence of a polymer, method for the preparation of said suspension, to the use of said suspension composition and said polymer in suspension.

Description

[0001] SUSPENSION OF MINERAL MATERIAL FIELD OF THE INVENTION The present invention relates suspension of at least one mineral material in water in the presence of at least one polymer, a method for the preparation of said suspension, to the use of said suspension and the use of said polymer as a dispersant for the transport of said mineral material. STATE OF ART Mineral processing involves the transportation and processing of large quantities of mineral materials. Combining solid mineral materials with a carrier fluid (usually water) to create a slurry has long been popular in the industry, principally due to the increased efficiency and alacrity of mineral processing steps through use of a slurry, since the finely ground particles afford greater surface area exposure to the extracting medium. The concentrate of the mineral ore is mixed with water to create a slurry and then pumped over a long distance to a port where it can be shipped for further processing. At the end of the pipeline, the mineral material is separated from the slurry to remove the water. This water is usually subjected to a waste treatment process before disposal or return to the mine. Pipeline transportation is a method of transportation which involves movement of solid, liquid or gaseous products over long distances through pipelines. Slurry pipelines offer an economic advantage over railroad transport and much less noise disturbance to the environment, particularly when mines are in extremely remote areas. Pipelines must be suitably engineered to resist abrasion from the solids as well as corrosion from the soil. Some of these pipelines are lined with high-density polyethylene (HDPE). Typical mineral materials that are transferred using slurry pipelines include coal, copper, iron ores, phosphate materials, limestone, lead, zinc, nickel, bauxite and oil sands. Slurry pipelines are also used to transport tailings from a mineral processing plant after the ore has been processed in order to dispose of the remaining rocks or clays. Mineral materials, when placed in suspension in water must exhibit good quality for the user, i.e. the Brookfield viscosity thereof must be such that there will be no risk of sedimentation or hardening of the settled mineral substance particles in order to ensure that they will be easy for the user to handle even after storage in tanks for several days without agitation. Furthermore, these suspensions must have as high a content of mineral material as possible to reduce the amount of water when transporting a given amount of mineral material, which reduces all the costs inherent in transportation. Increasing the amount of solid mineral material within this suspensions should also be aimed at, as well as controlling the viscosity of these particles suspension, specially for high concentration of solid mineral material. In particular, during its transport in a pipeline. WO2019092381 relates to a method for preparing an aqueous suspension of at least one phosphate material, comprising dispersing, in water, particles of phosphate material in the presence of at least one additive of the anionic polymer of acrylic acid or of methacrylic acid type. The invention also relates to the conditioning of the phosphate material associated with the anionic polymer, for its subsequent treatment with at least one strong acid, for the industrial preparation of phosphoric acid. There is still a need of improvement in the field of mineral material transport throw pipeline, i.e. the Brookfield viscosity thereof must be such that there will be no risk of sedimentation, particularly in the form of a suspension of mineral material particles in water. Improved stability of such suspensions is also sought, including resistance to particle sedimentation or control of flowability, which reduce pumping costs with a lower energy consumption. SUMMARY OF THE INVENTION Thus, an object of the present invention is a suspension comprising at least one mineral material in water in the presence of a polymer, its method of preparation, the use of said composition for the transport of mineral material and the use of the polymer as dispersant for the transport of the mineral material in the suspension. The inventors have surprisingly found that when adding a polymer in the suspension comprising at least one mineral material in water, such polymer is capable of providing the suspension with and excellent dispersing effect and / or and excellent viscosity- reducing effect by increasing particles of mineral material sedimentation time. It has further been discovered that controlling the viscosity of the suspension and increasing the resistance to sedimentation of the particles of mineral material serves for transporting more amount of mineral material through a pipeline in less time that are efficient from a technical point of view and also from an economical point of view. Thus, the first object of the present invention is related to a suspension comprising: (i)water; (ii) at least one mineral material, wherein the concentration by weight of particles of said mineral material is from 10% to 90% with respect to the total weight of the suspension ; and (iii) a polymer A, wherein polymer A comprises: - recurring units (a) of formula (I): (I) wherein R1and R2are each independently hydrogen or methyl, AO is a C2-C3 oxyalkylene group, n is a number from 3 to 200, and M1is hydrogen atom or a C1-C3 alkyl group. - recurring units (b) of formula (II): (II) wherein R3and R5are each independently hydrogen atom, methyl or (CH2)m1COOM2’,R4is hydrogen atom or methyl; M2 and M2’ are each independently selected from the groupconsisting of hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, an alkylammonium and a substituted alkylammonium group; m1 is 0 or 1; and - optionally recurring units (c) of formula (III): (III) wherein R6 is hydrogen atom or methyl; and M3is a C1-C18alkyl, C2-C18alkenyl or C2-C6hydroxyalkyl. A second aspect of the invention is a method for the preparation of a suspension according to any one of the first aspect, wherein the method comprises dispersing in water the mineral material, polymer A as defined in the first aspect and optionally polymer B as defined herein in particular embodiments of the first aspect. Another aspect of the present invention is the use of said suspension for the transport of the mineral material present in the suspension. A further aspect of the of the present invention is the use of Polymer A as defined in the first aspect, polymer B as defined herein in particular embodiments of the first aspect, or mixtures thereof as dispersant for the transport of a mineral material as defined in the first aspect. DETAILED DESCRIPTION OF THE INVENTION The term “dispersant”.refers to a polymer present in the suspension which has the ability to improve the dispersibility of mineral material particles within the aqueous suspension. Specially, when dispersants are used in aqueous suspensions of mineral materials, they induce a reduction in viscosity and resistance to sedimentation of particles of mineral material. Thus a suspension of mineral material in water in the presence of a dispersant will have a viscosity lower and high resistance to the sedimentation of mineral material than that of the same aqueous suspension not containing said dispersant. In particular, dispersant refers to polymer A as described below and optionally in combination with polymer B as described below.The term “mineral material”, with which one skilled in the art iswell familiar, as used herein refers to mineral sources which are mined for their commercial value, which are used in the industries based on their physical and / or chemical properties. Mineral materials can be divided into two major categories metallic ores such as iron, copper, zinc, lead, nickel, chromium; and non- metallic ores, also called industrial minerals or rocks such as limestone, sand, gravel, gypsum, coal, and phosphate rock.The term “particle size” refers to the average diameter in microns(µm) of the individual particles present in the mineral material. The particle size can be determined by means of laser diffraction, for example, using the conditions used in the examples. The length and width of the particles are measured, and they are assigned the size of the largest dimension (length). The average diameter is defined as the average length of the particles (summation of lengths of the analyzed particles among the number of particles analyzed).In the context of the present invention, the term “suspension”refers to a heterogeneous mixture in which solid particles (in particular particles of mineral material) are spread throughout a liquid phase (in particular mainly comprising water) without dissolving it, i.e. dispersed. The first object of the present invention is a suspension comprising at least one mineral material, water and polymer A. According to the present invention, the content of water in the suspension is preferably at least 90 wt.% water based on the total weight of the suspension, more preferably at least 85 wt.%, more preferably at least 80 wt.%, more preferably at least 70 wt.%, even more preferably at least 60 wt.%, still more preferably at least 50 wt.%. Mineral Material In one embodiment according to the present invention, suitable mineral materials are selected from phosphate material (i.e. phosphate rock), iron, coal, copper, carbonate-based minerals, zinc, and lead containing minerals. The most common phosphate materials (i.e. phosphate rocks) are those of calcium of the apatite group (Ca5(PO4)3(F,Cl,OH)), which are usually together with other minerals. The main phosphate minerals of the apatite group are fluoroapatite, chlorapatite, hydroxylapatite, carbonate-hydroxylapatite and francolite. Iron containing minerals are found mainly as minerals of iron oxide such as hematite, magnetite, goethite and limonite. The minerals that are mostly used as ore for making iron are hematite (Fe2O3) and magnetite (Fe3O4). Suitable examples of coal containing minerals include lignite, subbituminous coal, bituminous coal and anthracite coal. Suitable examples of copper containing minerals includes chalcopyrite, chalcocite, chrysocolla, malachite, atacamite, azurite, bornite, brochantite, cuprite (copper oxide), dioptase, rosasite and tetrahedrite. Suitable examples of carbonates-based minerals are calcium and / or magnesium carbonates, such calcite (CaCO3), dolomite (CaMg(CO3)2)and magnesite (MgCO3). Suitable examples of zinc containing minerals are zinc sulfide known as zinc blende or sphalerite (ZnS), a ferrous form of zinc blende known as marmatite [(ZnFe)S], and a zinc carbonate known as calamine or smithsonite (ZnCO3). Suitable examples of lead containing minerals include galena (PbS), cerrusite (PbCO3) and anglesite (PbSO4). In one embodiment according to the present invention mineral material is used in the form of solid particles with a size between 1 to 1000 µm, preferably from 20 to 400 µm. Preferably, the mineral material is selected from phosphate rock, iron ores and mixtures thereof; even more preferably from phosphate rock. According to the present invention, the concentration by weight of particles of mineral material in the suspension is from 10% to 90% with respect to the total weight of the suspension. Preferably, this concentration by weight of mineral material is from 30% to 70% by weight, more preferably from 40% to 80% by weight. In a particular preferred embodiment according to the present invention, mineral material is phosphate rock with a mineral material particle size range from 20 to 400 µm. The concentration of mineral material particles in the suspension is from 50% to 65% by weight. Polymer A The suspension according to the present invention comprises Polymer A, wherein said Polymer A comprises recurring units (a), recurring units (b) and optionally recurring units (c). The sequence of recurring units (a), recurring units (b) and, where present, recurring units (c) in polymer A may be alternating, block-like or be random. Preferably, the sequence of recurring units (a), recurring units (b) and, where present, recurring units (c) in polymer A is in a random manner. Recurring units (a) Recurring unit (a) refers to those represented by the following general formula (I): (I) wherein R1 and R2 are independently hydrogen or methyl; AO is a C2-C3 oxyalkylene group; n is a number from 3 to 200, and M1 is hydrogen atom or C1-C3 alkyl group. “*” represents the attachment point to the remaining part of the polymer. The oxyalkylene groups includes oxyethylene (-CH2-CH2-O), oxypropylene (-CH(CH3)-CH2-O and / or (-CH2-CH(CH3)-O) and mixtures thereof. (AO)nmay be those containing different type of AO obtained by random addition, block addition or mixture of these additions in average of n repeat units. In one embodiment according to the present invention, n is preferably 110 to 200, more preferably from 110 to 150 end even more preferably 110 to 130. In another embodiment, n in the Formula (I) is preferably 3 to 100, more preferably 3 to 80, even more preferably from 3 to 30 from the viewpoint of reduction slurry viscosity.In the context of the present invention, the term “alkyl” refersto a linear or branched hydrocarbon chain radical consisting of carbon and hydrogen atoms, containing no unsaturation, having the indicated number of carbon atoms, and which is attached to the rest of the molecule by a single bond. Specific examples of the recurring unit (a) represented by the above formula (I) include those obtained by polymerization of acrylic and methacrylic esters of polyalkylene glycols blocked with an alkyl group at one end such as methoxypolyethylene glycol, methoxypolyethylenepolypropylene glycol, ethoxypolyethylene glycol, ethoxypolyethylenepolypropylene glycol, propoxypolyethylene glycol and propoxypolyethylenepolypropylene glycol; and adducts of acrylic and methacrylic acids with ethylene oxide and propylene oxide. Preferably, in formula (I) R1 is hydrogen. Preferably, in formula (I) R2 is methyl. Preferably, in formula (I) AO is oxyethylene (EO). Preferably, in formula (I) M1 is a C1-C3 alkyl group, such as methyl, ethyl, n-propyl or isopropyl, more preferably methyl. More preferably, in formula (I) R1 is hydrogen, R2 is methyl, AO is oxyethylene (EO), n is number from 3 to 200, and M1 is a C1-C3 alkyl group, preferably methyl. More preferably, recurring unit (a) has formula (Ia): (Ia) wherein n is number from 3 to 200, preferably from 110 to 200 and / or from 3 to 100, more preferably from 110 to 150 and / or from 3 to 80, end even more preferably from 110 to 130 and / or from 3 to 30. Recurring unit (b) (II) wherein R3 and R5 are each independently hydrogen atom, methyl or (CH2)m1COOM2’; R4 is hydrogen atom or methyl; M2 and M2’ are independently selected from hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, an alkylammonium and a substituted alkylammonium group; m1 is 0 or 1. “*” represents the attachment point to the remaining part of the polymer. In the context of the present invention, the term “alkali metal” refers to any of lithium (Li), sodium (Na), potassium (K), rubidium (Rb) and cesium (Cs), preferably any of sodium and potassium.In the context of the present invention, the term “alkaline earthmetal” refers to any of beryllium (Be), magnesium (Mg), calcium(Ca), strontium (Sr) and barium (Ba), preferably any of magnesium and calcium.In the context of the present invention, the term “ammonium”refers to NH4+.In the context of the present invention, the term “alkyl ammonium”refers to a quaternary ammonium substituted by 1, 2 or 3 alkyl groups as defined herein. In particular, the alkyl groups have from 1 to 24 carbon atoms, preferably from 1 to 22 carbon atoms. In a particular embodiment, the alkyl ammonium is a quaternary ammonium substituted by 3 alkyl groups, preferably, wherein one or two of the alkyl groups are independently selected form a C1- C3 alkyl, preferably methyl, and the remaining alkyl groups are selected from a C8 to C24 alkyl group, preferably C8 to C22 alkyl group. Examples of alkylammonium are dimethyloctylammonium, dimethyldecylammonium, dimethyllauryl- ammonium, dimethylmyristylammonium, dimethylpalmitylammonium, dimethylcetylammonium, dimethylstearylammonium, dimethylbehenyl- ammonium, or mixtures thereof. Other suitable alkylammonium are methyldioctylammonium, methyldidecylammonium, methyldilauryl- ammonium, methyldimyristylammonium, methyldipalmitylammonium, methyldicetylammonium, methyldistearylammonium, methyldibehenyl- ammonium, or mixtures thereof. The alkyl ammonium group may be substituted with one or more substituents selected from the group consisting of methylammonium group, ethylammonium group, propylammonium group, isopropylammonium group, butylammonium group, 2-hydroxyethyl- trimethylammonium group and benzylammonium group. Specific examples of recurring unit (b) to be used include those obtained by polymerization of monocarboxylic acid units such as acrylic acid, methacrylic acid and crotonic acid and salts thereof with alkali metals, ammonium, amines and substituted amines; and unsaturated dicarboxylic acid such as maleic acid, itaconic acid, citraconic acid and fumaric acid and salts thereof with alkali metals, alkaline earth metals, ammonium, amines and substituted amines. Among them, monocarboxylic acid units such as acrylic acid, methacrylic acid are preferred. Preferably, in formula (II), R3and R5are both hydrogen. Preferably, in formula (II), R4 is a C1-C3 alkyl group, such as methyl, ethyl, n-propyl or isopropyl, more preferably methyl. Preferably, in formula (II), M2 is hydrogen. More preferably, in formula (II) R3 and R5 are both hydrogen, R4 is a C1-C3 alkyl group, preferably methyl, and M2 is hydrogen. More preferably, recurring unit (b) has formula (IIa): (IIa) Recurring unit (c) The Polymer A according to the present invention, optionally comprises a recurring units (c), which is different from recurring unit (b), having general formula (III): (III) wherein R6is hydrogen atom or methyl; and M3is a C1-C18alkyl, C2-C18 alkenyl group or a C2-C6 hydroxyalkyl. “*” represents the attachment point to the remaining part of the polymer.In the context of the present invention, the term “alkenyl” refersto a linear or branched hydrocarbon chain radical consisting of carbon and hydrogen atoms, containing at least one double bond, preferably from 1 to 3 double bonds, in particular 1, 2 or 3 double bonds, having the indicated number of carbon atoms (which is at least two), and which is attached to the rest of the molecule by a single bond. Specific examples of the recurring unit (c) include those obtained by polymerization of C1-C18 linear and branched alkyl (meth)acrylates; C1-C18linear and branched alkenyl (meth)acrylates; C2-C6hydroxyalkyl (meth)acrylates; di(C1- C18 linear and branched alkyl) esters of maleic acid, fumaric acid, itaconic acid and citraconic acid; and di(C1-C18linear and branched alkenyl) esters of maleic acid, fumaric acid, itaconic acid and citraconic acid. Among them, C1-C18 linear and branched alkyl (meth)acrylates is preferred. It is particularly preferable with regard to the solubility of the polymer A in water that M3in the above general formula (III) is C1-C4 alkyl, C2-C4 alkenyl, and C2-C4 hydroxyalkyl, though M3 is not particularly limited in the form but may be any of linear and branched ones. In one embodiment, recurring units (c) are present. In a preferred embodiment, recurring units (c) are absent. The polymer A according to the present invention, exhibits viscosity improvements of the suspension and shows higher sedimentation time for particles of mineral material independently of the type of mineral material used, when the molar ratio of the recurring units (a) and (b), i.e. a:b is 97:3 to 3:97, preferably is from 95:5 to 5:95, more preferably from 90:10 to 10:90. Thus, in a preferred embodiment, the molar ratio of the recurring units (a) and (b), i.e. a:b is 97:3 to 3:97, preferably is from 95:5 to 5:95, more preferably from 90:10 to 10:90. Preferably, in this embodiment recurring units (c) are absent from polymer A. In another embodiment according to the present invention, when (c) is present in polymer A, the molar ratio of the recurring units (a), (b) and (c), i.e. a:b:c, is (1-30):(10-80):(10-80), preferably (5-25):(5-75):(5-75), the resulting polymer A exhibits viscosity improvements of the suspension and shows higher sedimentation time for particles of mineral material independently of the type of mineral material used. Thus, in a preferred embodiment polymer A comprises recurring units (c) and the weight ratio of the recurring units (a), (b) and (c), i.e. a:b:c, is (1- 30):(10-80):(10-80), preferably (5-25):(5-75):(5-75). In one embodiment according to the present invention, polymer A is a polycarboxylic acid-based polymer, having a carboxylic acid group and a group selected from an oxyalkylene comprising recurring units (a) of formula (I) and recurring units (b) of formula (II) as previously described. According to the present invention, recurring unit (a) n is preferably 3 to 100, more preferably 3 to 80, even more preferably from 3 to 30. The molar ratio of the recurring units (a) and (b), i.e. a:b is 90:10 to 10:90. Preferably, in this embodiment recurring units (c) are absent from polymer A. In one embodiment according to the present invention, polymer A comprises recurring units (a) of formula (I) and recurring units (b) of formula (II) as previously described. According to the present invention, in recurring unit (a) n is preferably 110 to 200, more preferably from 110 to 150 end even more preferably 110 to 130. The molar ratio of the recurring units (a) and (b), i.e. a:b is 97:3 to 3:97. Preferably, in this embodiment recurring units (c) are absent from polymer A. In another embodiment according to the present invention, polymer A comprises recurring units (a) of formula (I), recurring units (b) of formula (II) and recurring units (c) of Formula (III). According to the present invention, in recurring units (a), n) n is preferably 3 to 100, more preferably 3 to 80, even more preferably from 3 to 30. The molar ratio of the recurring units (a), (b), and (c), i.e. a:b:c, is (1-30):(10-80):(10-80), preferably (5-25):(5-75):(5-75). In another embodiment according to the present invention, polymer A comprises recurring units (a) of formula (I), recurring units (b) of formula (II) and recurring units (c) of Formula (III). According to the present invention, in recurring units (a), n is preferably 110 to 200, more preferably from 110 to 150 end even more preferably 110 to 130. The molar ratio of the recurring units (a), (b), and (c), i.e. a:b:c, is (1-30):(10-80):(10-80), preferably (5-25):(5-75):(5-75). The polymer A according to the present invention can be obtained by known processes, e.g. radical polymerization, living radical polymerization, ion polymerization, or the like, and preferably radical polymerization. That is, the polymer A is obtained by polymerizing monomer (I), monomer (II) and optionally monomer (III), in particular in a suitable solvent at the above mentioned ratios of recurring units (a) of formula (I) (corresponding to the ratio of monomer (I)), recurring units (b) of formula (II) (corresponding to the ratio of monomer (II)) and recurring units (c) of Formula (III) (corresponding to the ratio of monomer (III)). The solvent to be used in the solution polymerization includes water, methyl alcohol, ethyl alcohol, isopropyl alcohol, benzene, toluene, xylene, cyclohexane, n-hexane, ethyl acetate, acetone, methyl ethyl ketone and so on, and mixtures thereof. It is preferable from the viewpoints of manageability and reaction equipment to use water, methyl alcohol, ethyl alcohol, isopropyl alcohol or mixtures thereof. As a polymerization initiator, known initiators such as azo-based initiators, peroxide-based initiators, macro-initiators, and redox-based initiators can be used. For polymerization solvents containing water, examples of the polymerization initiator include ammonium salt and an alkaline metal salt of persulfuric acid, hydrogen peroxide, and water-soluble azo compounds such as 2,2'- azobis(2-amidinopropane) dihydrochloride and 2,2'-azobis(2- methylpropionamide) dihydrate. For polymerization solvents not containing water, examples of the polymerization initiator include peroxides such as benzoyl peroxide and lauroyl peroxide, and aliphatic azo compounds such as azobisisobutyronitrile. A chain-transfer agent may further be used as a molecular weight modifier or for other purposes according to need. Examples of the chain-transfer agent include thiol-based and halogenated hydrocarbon-based chain-transfer agents. Preferred are thiol- based chain-transfer agents, such as those defined below for polymer B. - Monomer (I) is represented by general formula (VII) (VII) wherein R1, R2, AO, n and M1 are as defined above for recurring units (a). Specific examples of the monomer (I) represented by the above formula (VII) include acrylic and methacrylic esters of polyalkylene glycols blocked with an alkyl group at one end such as methoxypolyethylene glycol, methoxypolyethylenepolypropylene glycol, ethoxypolyethylene glycol, ethoxypolyethylenepolypropylene glycol, propoxypolyethylene glycol and propoxypolyethylenepolypropylene glycol; and adducts of acrylic and methacrylic acids with ethylene oxide and propylene oxide. More preferably, monomer (I) has formula (VIIa): ^^^^^^ ^^^^^^^^^^^^^^^^^^^^(VIIa) wherein n is number from 3 to 200, preferably from 110 to 200 and / or from 3 to 100, more preferably from 110 to 150 and / or from 3 to 80, end even more preferably from 110 to 130 and / or from 3 to 30. Monomer (II) is represented by general Formula (VIII): (VIII) wherein M2, R3, R4, and R5are as defined above for recurring units (b). Specific examples of monomer (II) to be used include monocarboxylic acid units such as acrylic acid, methacrylic acid and crotonic acid and salts thereof with alkali metals, ammonium, amines and substituted amines; and unsaturated dicarboxylic acid monomers such as maleic acid, itaconic acid, citraconic acid and fumaric acid and salts thereof with alkali metals, alkaline earth metals, ammonium, amines and substituted amines. More preferably, monomer (II) has formula (VIIIa): ^^^^^^ ^^^^^ (VIIIa) Monomer (III) is optionally used for obtaining polymer A. Monomer (III) is represented by general formula (IX): wherein R6 and M3 are as defined above for recurring units (c). Specific examples of monomer (III) include C1-C18linear and branched alkyl (meth)acrylates; C1-C18 linear and branched alkenyl (meth)acrylates; C2-C6hydroxyalkyl (meth)acrylates; di(C1- C18linear and branched alkyl) esters of maleic acid, fumaric acid, itaconic acid and citraconic acid; and di(C1-C18 linear and branched alkenyl) esters of maleic acid, fumaric acid, itaconic acid and citraconic acid. In one embodiment according to the present invention, polymer A is obtained by polymerizing the monomers (I) and monomer (II), wherein n of monomer (I) according to Formula (VII) is preferably 3 to 100, more preferably 3 to 80, even more preferably from 3 to 30. In another embodiment according to the present invention, polymer A is obtained by polymerizing the monomers (I) and monomer (II), wherein n of monomer (I) according to Formula (VII) is preferably 110 to 200, more preferably from 110 to 150 end even more preferably 110 to 130. In another embodiment according to the present invention, polymer A is obtained by polymerizing the monomers (I), monomer (II) and monomer (III), wherein n of monomer (I) according to Formula (VII) is preferably 3 to 100, more preferably 3 to 80, even more preferably from 3 to 30. In another embodiment according to the present invention, polymer A is obtained by polymerizing the monomers (I), monomer (II) and monomer (III), wherein n of monomer (I) according to Formula (VII) is preferably 110 to 200, more preferably from 110 to 150 end even more preferably 110 to 130. In another embodiment according to the present invention, Polymer A could be further obtained by a second method which comprises the steps of: a) polymerization of: - monomer (II); wherein monomer (II) is represented by general formula (VIII) as previously described, as well as - optionally monomer (III), wherein monomer (III) is represented by general formula (IX) as previously described; b) esterification of the polymer compound obtained in a) with at least one compound of formula (VI): HO-[AO]nM1(VI) wherein AO, n and M1 are as defined above in recurring unit a). The polymer compound obtained in step a) can be prepared by known processes, e.g. radical polymerization, living radical polymerization, ion polymerization, or the like, and preferably radical polymerization. That is obtained by polymerizing monomer monomer (II) and optionally monomer (III), in particular in a suitable solvent. The solvent to be used in the solution polymerization includes water, methyl alcohol, ethyl alcohol, isopropyl alcohol, benzene, toluene, xylene, cyclohexane, n-hexane, ethyl acetate, acetone, methyl ethyl ketone and so on, and mixtures thereof. It is preferable from the viewpoints of manageability and reaction equipment to use water, methyl alcohol, ethyl alcohol, isopropyl alcohol or mixtures thereof. As a polymerization initiator, known initiators such as azo-based initiators, peroxide-based initiators, macro-initiators, and redox-based initiators can be used. For polymerization solvents containing water, examples of the polymerization initiator include ammonium salt and an alkaline metal salt of persulfuric acid, hydrogen peroxide, and water-soluble azo compounds such as 2,2'- azobis(2-amidinopropane) dihydrochloride and 2,2'-azobis(2- methylpropionamide) dihydrate. For polymerization solvents not containing water, examples of the polymerization initiator include peroxides such as benzoyl peroxide and lauroyl peroxide, and aliphatic azo compounds such as azobisisobutyronitrile. A chain-transfer agent may further be used as a molecular weight modifier or for other purposes according to need. Examples of the chain-transfer agent include thiol-based and halogenated hydrocarbon-based chain-transfer agents. Preferred are thiol- based chain-transfer agents, such as those defined below for polymer B. The polymer obtained during step a) is in particular a polyacrylic acid, polymethacrylic acid, polymethylacrylate and / or a copolymer of an acrylic acid, methacrylic acid and polymethylacrylate acid which could be obtained commercially from a variety of suppliers. For the esterification step b) acids and / or bases may be added as catalysts. Suitable examples of acid catalysts are p- toluenesulphonic acid, phosphoric acid, sulphuric acid. Suitable examples of bases catalysts are sodium hydroxide, sodium ethoxide and sodium methoxide. Preferably, the esterification step b) acids catalysts are used. Preferably, the esterification of step b) takes place at a temperature of 120-200°C, in particular 160- 180°C. In another embodiment according to the present invention, the second method for obtaining Polymer A comprises the steps of: a) polymerization of monomer (II) as previously described; wherein monomer (II) is represented by general formula (VIII) as previously described, and b) esterification of the polymer compound obtained in a) with at least one compound of formula (VI) as previously described. Reaction condition are as previously described. In a particular preferred embodiment, polymer compound obtained during step a) is in particular a polyacrylic acid and / or polymethacrylic acid, which could be obtained commercially from a variety of suppliers. In one embodiment according to the present invention polymer A has an average molecular weight (Mw) of 5,000 to 200,000 g / mol, preferably of 10,000 to 100,000 g / mol, still preferably of 15,000 to 70,000 g / mol. Polymer B The suspension according to present invention further comprises a Polymer B, wherein polymer B is a phosphate-based polymer comprising recurring units (a), recurring units (d) and recurring units (e). Recurring units (a) The recurring (a) present in polymer B are as those described in the polymer A, i.e. having formula (I). In recurring units (a) of formula (I) in polymer B, n is 3 to 200, preferably 4 to 120, more preferably 4 to 80, even more preferably 4 to 50 and even more preferably 4 to 30. This particular values are particularly advantageous from the viewpoint of the dispersibility of the polymer in the composition and viscosity reducing effect. Specific examples include of recurring units (a) in polymer B may include those obtained by polymerization of ω-methoxy polyoxyalkylene methacrylate, ω-methoxy polyoxyalkylene acrylate, among which ω-methoxy polyoxyalkylene methacrylate is preferable. Recurring units d In the Polymer B according to the present invention, recurring units (d) is represented by the following formula (IV): (IV) wherein R7 represents hydrogen atom or methyl, R8 represents C2 to C12 alkylene group, m2denotes a number from 1 to 30, and M4and M5 are represent independently a hydrogen atom, an alkali metal or an alkaline earth metal. “*” represents the attachment point to the remaining part of the polymer. Examples of recurring units (d) include those obtainable by polymerization of phosphoric mono(2-hydroxyethyl) methacrylate, phosphoric mono(2-hydroxyethyl) acrylate, polyalkylene glycol mono(meth)acrylate acid phosphate, etc. From the viewpoint of easiness of production and stability of qualities of the product, phosphoric mono(2-hydroxyethyl) methacrylate is preferable. Preferably, in formula (IV) R7 is methyl. Preferably, in formula (IV) R8is C2 alkylene group. Preferably, in formula (IV) m2is a number from 1 to 20, more preferably 1 to 10, even more preferably 1 to 5. Preferably, in formula (IV) M4and M5are both hydrogen atom. More preferably, in formula (IV) R7 is methyl, R8 is C2 alkylene group, m2 is a number from 1 to 20, and M4 and M5 are both hydrogen atom. More preferably, recurring unit (d) has formula (IVa): (IVa) Recurring unit (e) In Polymer B according to the present invention, recurring unit (e) is represented by the following formula (V): wherein R9and R11represent independently a hydrogen atom or methyl group, R10 and R12 each represents independently a C2 to C12 alkylene group, m3and m4each represents independently a number from 1 to 30, and M6 represents a hydrogen atom, an alkali metal or an alkaline earth metal. “*” represents the attachment point to the remaining part of the polymer. Specific examples of recurring units (e) include those obtained by polymerization of phosphoric di- [(2-hydroxyethyl) methacrylic acid] ester, phosphoric di-[(2-hydroxyethyl) acrylic acid] ester, etc. In particular, phosphoric di-[(2-hydroxyethyl) methacrylic acid] ester is preferable from the viewpoint of easiness of production and stability of qualities of the suspension. Preferably, in formula (V) R9and R11are both methyl. Preferably, in formula (V) R10 and R12 are both C2 alkylene group. Preferably, in formula (V) m3 and m4 each represents a number of 1 to 30, preferably from 1 to 20, more preferably 1 to 10, even more preferably 1 to 5, still more preferably 1. Preferably, in formula (V) M6is hydrogen atom. More preferably, in formula (V) R9 and R11 are both methyl, R10 and R12are both C2 alkylene group, m3and m4are independently a number from 1 to 20, and M6 is hydrogen atom. More preferably, in formula (V) recurring unit (e) R9and R11are both methyl, R10and R12are both C2 alkylene group, m3and m4are both 1, and M6 is hydrogen atom. More preferably, recurring unit (e) has formula (Va): The recurring units (d) and (e) are obtained by polymerization of the corresponding monomers which are phosphate compounds having an unsaturated bond and a hydroxyl group. These monomers are commercially available products may contain compounds other than the monoester (i.e. recurring units d) and diester (i.e. recurring units e). The monomers used for obtaining recurring units (d) and (e) may be blended to use it as a monomer mixture to be used in the polymerization reaction to obtain the polymer having the corresponding recurring units. As the monomer mixture used for obtaining a polymer comprising recurring units (d) and (e), a commercially available product containing a monoester and a diester may be used. These products are available under the name of Phosmer M, Phosmer PE and Phosmer P (Unichemical), JAMP514, JAMP514P and JMP100 (all of these products are manufactured by Johoku Chemical Co., Ltd.), Light Ester P-1M, Light Acrylate P-1A (all of these products are manufactured by Kyoeisha Kagaku Kogyo), MR200 (Daihachi Chemical Industry Co., Ltd.), Kayamer (NIppon Kayaku Co., Ltd.) and Ethyleneglycol methacrylate phosphate (Aldrich reagent). In one embodiment according to the present invention, the molar ratio between recurring units (d) and recurring units (e), i.e. d:e is preferably 99:1 to 4:96 and more preferably 99:1 to 5:95, provided that the total is 100. In one embodiment according to the present invention, the molar ratio of the recurring units (a), and the sum of recurring units (d) and (e), i.e. (a: (d+e)) is preferably 5:95 to 95:5 and more preferably 10:90 to 90:10. The molar ratio of the recurring units (a), (d) and €, i.e. a:d:e, is preferably 5 to 95:3 to 90:1 to 80. This means 5 to 95 of recurring unit (a), 3 to 90 of recurring unit (d) and 1 to 80 of recurring unit (e), provided that the total of recurring units (a),(d) and(e) is 100. More preferably, the molar ratio of the recurring units a, d and e, i.e. a:d:e, is 5 to 96:3 to 80:1 to 60. Also, the molar ratio pf recurring unit (d) and (e), i.e. d:e, is preferably 99:1 to 4:96 and more preferably 99:1 to 5:95 Monomer (I) is represented by general formula (VII) as previously described for polymer A. With regard to the monomer (I) used for obtaining polymer B, n in the formula (VII) is 3 to 200, preferably 4 to 120, more preferably 4 to 80 , even more preferably 4 to 50 and even more preferably 4 to 30. These values are particularly advantageous from the viewpoint of the dispersibility of the polymer in the composition and viscosity reducing effect. Monomer (IV) is represented by general formula (X): wherein R7, R8, m2, M4and M5are as defined above for recurring units (d). Examples of monomer (IV) include phosphoric mono(2-hydroxyethyl) methacrylate, phosphoric mono(2-hydroxyethyl) acrylate, polyalkylene glycol mono(meth)acrylate acid phosphate, etc. From the viewpoint of easiness of production and stability of qualities of the product, phosphoric mono(2-hydroxyethyl) methacrylate is preferable. Monomer (V) is represented by general Formula (XI): (XI) wherein R9, R10, R11, R12, m3, m4 and M6 are as defined above for recurring units (e). Specific examples of monomer (V) include phosphoric di- [(2- hydroxyethyl) methacrylic acid] ester, phosphoric di-[(2- hydroxyethyl) acrylic acid] ester, etc. In particular, phosphoric di-[(2-hydroxyethyl) methacrylic acid] ester is preferable from the viewpoint of easiness of production and stability of qualities of the suspension. Monomers (IV) and (V) may be provided as a mixture for the polymerization reaction. Such a mixture may be provided as a commercially available product containing a phosphate monoester and a phosphate diester. These products are available under the name of Phosmer M, Phosmer PE and Phosmer P (Unichemical), JAMP514, JAMP514P and JMP100 (all of these products are manufactured by Johoku Chemical Co., Ltd.), Light Ester P-1M, Light Acrylate P-1A (all of these products are manufactured by Kyoeisha Kagaku Kogyo), MR200 (Daihachi Chemical Industry Co., Ltd.), Kayamer (NIppon Kayaku Co., Ltd.) and Ethyleneglycol methacrylate phosphate (Aldrich reagent). Preferable compounds as the monomers (I), (IV) and (V) are those described above. Also, the aforementioned commercially available products and reaction products may be used. The present invention found that polymer derived from specific phosphates, Polymer B, is useful for the reduction of the viscosity of the suspension as one purpose of the present invention. The phosphate based polymer, polymer B, according to the present invention, is a polymer obtained by polymerization of a monomer (I), with a monomer (IV) and monomer (V) or mixtures thereof Preferably, Polymer B, is a polymer obtained by polymerization of a monomer (I) with a mixture of monomers containing monomer (IV) and monomer (V). In the obtaining of the polymer B, the above mentioned monomers may be polymerized in the presence of a chain transfer agent. The temperature of the reaction between the monomers (I), (IV) and (V) is preferably 40 to 100°C and more preferably 60 to 90°C and the reaction pressure is preferably 101.3 to 111.5 kPa (1 to 1.1 atm) and more preferably 101.3 to 106.4 kPa (1 to 1.05 atm). In the present invention, the monomers (I), (IV) and (V) are reacted at pH 7 or less. In the present invention, the pH at 20°C of the reaction solution collected during the reaction (from the beginning to the end of the reaction) shall be pH during the reaction. Usually, the reaction may be initiated under conditions (monomer ratio, solvent, other components etc.) where the pH is made evidently 7 or less during the reaction from the viewpoint of suppressing the gelation. The pH of the reaction system can be adjusted by using inorganic acids (e.g., phosphoric acid, hydrochloric acid, nitric acid and sulfuric acid) and bases such as NaOH, KOH, triethanolamine and the like according to the need. The chain transfer agent is a material, which has the function of initiating a chain transfer reaction (a reaction in which polymer radicals that are under growing, are reacted with other molecules to cause radical active points to be transferred) and is added with the intention of transferring a chain unit. The chain transfer agent is preferably used in the polymerization from the viewpoint of limiting gelation, regulating a proper molecular weight and designing the performances of the hydraulic composition dispersant. Examples of the chain transfer agent include thiol-based chain transfer agents and hydrocarbon halide-based chain transfer agents. Among these agents, thiol-based chain transfer agents are preferable. As the thiol-based chain transfer agent, those having a -SH group and especially, those represented by the formula HS-R-Eg (wherein R represents a group derived from a hydrocarbon having 1 to 4 carbon atoms, E represents -OH, -COOM, -COOR' or -SO3M group, where M represents a hydrogen atom, a monovalent metal, a divalent metal, an ammonium group or an organic amine group, R' represents an alkyl group having 1 to 10 carbon atoms and g denotes an integer from 1 to 2). Examples of the thiol-based chain transfer agent include mercaptoethanol, thioglycerol, thioglycolic acid, 2- mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, octyl thioglycolate and octyl 3-mercaptopropionate. Mercaptopropionic acid and mercaptoethanol are preferable and mercaptopropionic acid is more preferable from the viewpoint of a chain transfer effect in the copolymerization reaction of the system containing the monomers 1 to 3. One or two or more of these compounds may be used. Examples of hydrocarbon halide-based chain transfer agent include carbon tetrachloride and carbon tetrabromide. Examples of other chain transfer agents may include α- methylstyrene dimer, terpinolene, α-terpinene, v-terpinene, dipentene and 2-aminopropane-1-ol. These chain transfer agents may be used either alone or in combinations of two or more. In one embodiment according to the present invention, polymer B is obtained by polymerizing the monomers (I), monomer (IV) and monomer (V), wherein n of monomer (I) according to Formula (VII) is preferably 110 to 200, more preferably from 110 to 150 end even more preferably 110 to 130. In another embodiment according to the present invention, polymer B is obtained by polymerizing the monomers (I) with a monomer mixture containing monomer (IV) and monomer (V), wherein n of monomer (I) according to Formula (VII) is preferably 110 to 200, more preferably from 110 to 150 end even more preferably 110 to 130. The weight average molecular weight (Mw) of the polymer B according to the present invention is preferably 10,000 to 150,000 g / mol. This polymer B has an average Mw of 10,000 g / mol or more, preferably 12,000g / mol or more, more preferably 13,000 g / mol or more, even more preferably 14,000 g / mol or more and even more preferably 15,000 g / mol or more. These molecular weights are particularly advantageous from the viewpoint of dispersing effect and viscosity reducing effect. Polymer B has Mw of and 150,000 g / mol or less, preferably 130,000 g / mol or less, more preferably 120,000 g / mol or less, even more preferably 110,000 g / mol or less and even more preferably 100,000 g / mol or less. These molecular weights are particularly advantageous from the viewpoint of limiting gelation and improving the performances including a dispersing effect and viscosity reducing effect. The Mw of the polymer B is preferably 12,000 to 130,000 g / mol, more preferably 13,000 to 120,000 g / mol, even more preferably 14,000 to 110,000 g / mol and even more preferably 15,000 to 100,000 g / mol to satisfy the above both conditions. The average Mw of the polymer B (and also of polymer A) are values measured by a gel permeation chromatographic (GPC) method carried out in the following conditions: Column: G4000PWXL+G2500PWXL (Tosoh) Eluent: 0.2 M phosphoric acid buffer / CH3CN = 9 / 1 Flow rate: 1.0 mL / min Column temperature: 40°C Detection: refractive index (RI) Sample size: 0.2 mg / mL Standard material: Based on polyethylene glycol In one embodiment according to the present, suspension contains the polymer A and polymer B. The weight ratio between both polymers can be arbitrarily adjusted for the intended use. However, the ratio (polymer A / polymer B) by weight of the polymer A to the polymer B is preferably 95:5 to 5:95, more preferably 90:10 to 10:90 and even more preferably 80:20 to 20:80. These ratios are particularly advantageous for achieving viscosity-reducing effect. Also, the weight ratio of the polymer A and polymer B may be from 70:30 to 15:85, preferably 60:40 to 15:85 and more preferably 50:50 to 20:80. These weight ratios are particularly advantageous from the viewpoint of viscosity-reducing effect. Method of preparation In a particular advantageous manner, the preparation method according to the present invention allows a particularly useful and effective control of the viscosity and stability, that makes possible to use this suspension under very varied and advantageous conditions. In particular for its handling (i.e. transport). The method for preparing a suspension according to the present invention, comprising at least one mineral material, the Brookfield viscosity of which, at 25ºC, at 30 rpm at a concentration of mineral material from 10% to 90% by weight based on total amount of composition, is less than 5000 mPa.s, comprising dispersing in water particles of mineral material whose particle size is between 1 to 1000 µm, in the presence of polymer (i.e. polymer A as described herein, Polymer B as described herein, and optionally polymer A in combination with polymer Bas described herein), hereinafter referred as “dispersant”. Themineral material to be dispersed may have different origins depending of kind of mineral to be used. As previously described, it is been discovered that the presence of a dispersant in a mixture comprising the mineral material and water provides control of the viscosity of the resulting suspension reducing mineral material sedimentation time, with generally facilitates its transport. When the viscosity is so reduced, it has been found that larger amounts of mineral material may be transported. According to the present invention the amount by weight (dry / dry) of dispersant (i.e. polymer A, polymer B or a mixture of polymer A and polymer B, wherein polymer A and polymer B are as previously described) used to prepare the suspension is between 0.005 to 2%, preferably from 0.01 to 2%, more preferably 0.05 to 2%, based on the amount of mineral material. According to the present invention the mineral material is selected from a phosphate material, iron, coal, copper, carbonate- based mineral, zinc, and lead, preferably from a phosphate material and iron, more preferably from phosphate material. In the preparation of the suspension according to the present invention, the mineral material is used in the form of particles with a particle size between 1 to 1000 µm, preferably from 20 to 400 µm. Preferably for the preparation method according to the present invention, the dispersion in water of particles of mineral material is carried out under stirring, more preferably under mechanical stirring at 25ºC. In one embodiment according to the present invention, the suspension comprises water and particles of at least one mineral material dispersed in the presence of a dispersant (i.e. Polymer A as described herein, in particular with an average molecular weight (Mw) ranging from 5,000 to 200,000 g / mol). In one embodiment according to the present invention, the suspension comprises water and particles of at least one mineral material dispersed in the presence of a dispersant (i.e. Polymer B as described herein, in particular with an average molecular weight (Mw) ranging from 10,000 to 150,000 g / mol). In another embodiment according to the present invention, the suspension comprises water and particles of at least one mineral material dispersed in the presence of a dispersant (i.e. polymer A as described herein in combination with polymer B as described herein, in particular with an average molecular weight (Mw) of Polymer A ranging from 5,000 to 200,000 g / mol and an average molecular weight (Mw) of Polymer B ranging from 10,000 to 150,000 g / mol). Preferably for the preparation method according to the present invention, the mineral material to be dispersed in water is a phosphate material (i.e. phosphate rock) and the dispersant is Polymer A. Preferably, polymer A has an average molecular weight (Mw) ranging from 10,000 to 100,000 g / mol, still preferably of 15,000 to 70,000 g / mol. The method for preparing a suspension of particles of at least one mineral material according to the present invention makes it possible to obtain such suspension whose properties in particular its viscosity, are particularly advantageous. This suspension preferably has a high resistance to the sedimentation of mineral material particles according to the invention, in particular compared with polymer-free suspension of the same viscosity. Use of the suspension The properties of the suspension according to the present invention (i.e. high resistance to sedimentation of mineral material), make it possible the use of this suspension under varied conditions in particular for transport the mineral material comprised in the suspension. Preferably the method of transport according to the invention could be carried out be means at least sea transport or land transport. In a particular preferred manner, it is carried out by means of land transport, for example, by rail or road, or by means of a pipeline or a mini-pipeline. The properties of the aqueous suspension according to the invention are particularly suitable for a method of transport by means of a pipeline. Use of the polymer According to the present invention, as previously described, the polymer in the suspension of the invention acts as a dispersant controlling viscosity, improving stability and resistance to the sedimentation of mineral material in the suspension to facilitate its transport. The amount by weight (dry / dry) of dispersant according to the present invention (i.e. polymer A or a mixture of polymer A and polymer B, wherein polymer A and polymer B are as previously described) is used in an used to prepare the suspension is between 0.005 to 2%, preferably from 0.01 to 2%, more preferably 0.05 to 2%, based on the amount of mineral material of the suspension. In one embodiment according to the present invention, Polymer A is used as a dispersant for the transport of mineral material. In one embodiment according to the present invention, Polymer B is used as a dispersant for the transport of mineral material. In another embodiment according to the present invention, polymer A in combination with Polymer B, are used as a dispersant for the transport of mineral material Preferably, Polymer A is used as a dispersant for the transport of mineral material. The following examples are given in order to provide a person skilled in the art with a sufficiently clear and complete explanation of the present invention, but should not be considered as limiting of the essential aspects of its subject, as set out in the preceding portions of the description. EXAMPLES The following examples are given in order to provide a person skilled in the art with a sufficiently clear and complete explanation of the present invention, but should not be considered as limiting of the essential aspects of its subject, as set out in the preceding portions of this description. The first part of the Examples section corresponds to the preparation of suspension according to the present invention. The second part of the Examples section corresponds to the viscosity test and dispersion evaluation of suspension. The third part of the Examples section refers to the stability of the suspension according to the invention. Table 1: Summary of examples and comparative examples according to the present invention.

[0002] e ) 0 g l 0 0 a w o M m 2 00 re / , g 9 ,6 va ( - 3 2 O E )V e ( E r r P a e D m si o - n A s o M e M - - E h H tn ) e V r de I ap g ( r ea r Eh e P h t c m M o -A ne n M i b o M - - E H so l t ) a s I re l I m a ( u i n r r e em , e ta o 1 ta m no A A e l M - A M A l y e w - M ba rc t a t a e R a h t e h p a ) t s h I E E E h e o p ( - -) t m h s ) -) 0 n on p o r 3 3 2 I o o h e 2 2 1 m no p mo ( ( ( . m i d n G G G sw l o E E E o o e e M P P P l c t t E E E l yl a a - M M M o g ly l f r e r y c rc t et s s s s a ne ah a h h g a e e e l t t i w Y Y Y er y e e e a ht m m w l l r e e y y a l l ) l yl h h lu a a k r i c b r o s s s a o t t p ey e c y e e e t y d x x l n e R e e t Y Y Y e . x i o o o i a - o c r r m M m P h r h a d d e ( t e t c y y g n b e i H H a i mu m l - - r e n - yr 2 2 ev v s ω c : : a i l e : a E E t t 1 2 o a b lo E - ht PM PD hg r el el my m G eM - -A i a p p s d E : e p m m e P A A M W m a a e d M E : o x x E A E H w C E E h T d a M • M • H • • M • 5 Example 1. Preparation and characterization of aqueous suspension The preparation of suspension is carried out by mixing phosphate material (i.e Phosphate rock) particles with water to obtain a mixture at the desired mineral content. If necessary, the dispersant according to the present invention is added to the aqueous suspension to obtain the desired amount. Particle size distribution of phosphate material: The particle size distribution of phosphate rock particles is characterized at 22ºC by laser diffraction using a Malvern Mastersizer 2000 diffraction granulometer with 2-propanol as solvent. The results are shown in Table 2: Table 2 Median particle sizeSize (^m) d0.1050.46 d0.50 91.40 d0.90160.72 d(0.10): Represents the particle diameter value of the particles population which 10% by volume of the particles have a size smaller than this value d(0.50): Represents the 50% by volume of the particles have a size smaller than this value d(0.90): Represents particle diameter value of the particles population which the 90% by volume of the particles have a size with diameters smaller than this value Example 2. Viscosity tests and dispersion evaluation Viscosity of Phosphate rock suspensions by Brookfield: 200 mL of aqueous phosphate rock suspension in water are introduced in 400 mL beaker at 25ºC under mechanical stirring (600 rpm for 5 min). If necessary, the dispersant according to the invention is added in the dry / dry amount of dry additive relative to the amount of dry phosphate rock. Stirring is stopped and the viscosity is measured at 22 ºC by means of a Brookfield viscometer equipped with a type S62 spindle at a rotation speed of 30 rppm. The results are shown in table 3. Table 3 Mineral content Viscosity %(w / w)a(mPa·s) Comparative 1 Not 65 measurable Example 1 b 65 410 at 2% (w / w) Example 2 65 4450 at 2% (w / w)ba)In the table above, the mineral content is expressed as the weight of mineral material with respect to the total weight of the suspension. b)In the table above, the w / w concentration define in Example 1 and Example 2 refer to the weight of dispersant (i.e. polymer A or the combination of polymer A and polymer B) with respect to the weight of mineral material. Whereas Comparative 1 (suspension without dispersant) show high viscosity values, the suspension comprising the polymer according to present invention (Ex 1 and 2) has a controlled viscosity which make suspension easily to handle and transportable Viscosity of Phosphate rock suspensions by IKA: 200 mL of aqueous phosphate rock suspension are introduced in 1000 mL beaker at 25ºC under mechanical stirring with a IKA® EUROSTAR POWER CONTROL-VISC equipped with stirrer Z-2310 (ø 110 mm diameter with six choppers of 30 mm height) at rotation speed of 50 rpm for 2 min. If necessary, the additive according to the invention is added in the dry / dry amounts of dry additive relative to the amount of dry phosphate rock. The viscosity measurement is started and, after 1 min, the viscosity is measured at 25 ºC by means of the IKA® EUROSTAR POWER CONTROL-VISC system. Afterwards the rotation speed is increased stepwise (from 50 rpm to 1300 rpm) with an appropriate waiting period (1 min) at each measurement point to analyze the viscosity. The IKA® EUROSTAR system records the electrical torque of the engine which correlates to the viscous drag on the immersed stirrer and thus the viscosity of the phosphate rock suspension is obtained at each measuring point. The results are shown in Table 4. The results are shown in table 4. Table 4 Mineral Shear rate Torque content a (s-1) (mN) %(w / w) 15 42.2 Comparative 1 65 20 56.6 Example 1 15 37.7 b 65 at 0.1% (w / w) 20 49.5 Example 1 15 33 b 65 at 0.3% (w / w) 20 43.5 Example 1 15 32 b 65 at 0.4% (w / w) 20 40.9 Example 2 15 40.7 65 at 0.1% (w / w) 20 53.5 Example 2 15 34.7 65 at 0.3% (w / w)b20 44.4 a)In the table above, the mineral content is expressed as the weight of mineral material with respect to the total weight of the suspension. b)In the table above, the w / w concentration define in Example 1 and Example 2 refer to the weight of dispersant (i.e. polymer A or the combination of polymer A and polymer B) with respect to the weight of mineral material. Whereas Comparative 1 (suspension without dispersant) show high viscosity values, the suspension comprising the additives according to present invention (Ex 1 and 2) has a controlled viscosity over the time which make suspension easily to handle and transportable. Example 3. Stability of aqueous suspension 200 mL of aqueous phosphate rock suspension are introduced into 400 mL beaker at 25ºC under mechanical stirring (600 rpm- for 5 minutes).If necessary, the dispersant according to present invention is added in the dry / dry amount relative to the amount of dried phosphate rock. Stirring is stopped and the viscosity is measured at 22ºC continuously over time by means of Brookfield viscometer equipped with a type S62. The results are shown in table 3. Mineral Time Viscosity content % (min) (mPa·s) w / w)aComparative 1 65 1 Not 2 measurable 5 15 Example 1 65 1 435 at 2% (w / w)b2 980 5 9500 15 Not measurable Example 2 65 1 4590 at 2% (w / w)b2 4300 5 3520 15 4400 a)In the table above, the mineral content is expressed as the dry weight of mineral material with respect to the total weight of the suspension. b)In the table above, the w / w concentration define in Example 1 and Example 2 refer to the weight of dispersant (i.e. polymer A or the combination of polymer A and polymer B) with respect to the weight of mineral material. Whereas Comparative 1 does not allow viscosity to be measuredbecause it’s too high to be measured. It can be seen that thepresence of additives according to the present invention (Ex 1 and 2) makes it possible to remain the viscosity constant for a longer period of time to obtain a suspension which is more stable.

Claims

CLAIMS 1. A suspension comprising: (i)water; (ii) at least one mineral material, wherein the concentration by weight of particles of said mineral material is from 10% to 90% with respect to the total weight to the suspension; (iii) a polymer A, wherein polymer A comprises: - recurring units (a) of formula (I):(I) wherein R1 and R2 are each independently hydrogen or methyl, AO is a C2-C3 oxyalkylene group, n is a number from 3 to 200, and M1 is hydrogen atom or C1-C3 alkyl group; - recurring units (b) of formula (II):(II) whereinR3 and R5 are each independently hydrogen atom, methyl or (CH2)m1COOM2’,R4 is hydrogen atom or methyl; M2 and M2’ represent independently hydrogen atom, analkali metal, an alkaline earth metal, ammonium, an alkylammonium or substituted alkylammonium group; m1 is 0 or 1; and - optionally recurring units (c) of formula (III):(III) wherein R6is hydrogen atom or methyl; and M3 is a C1-C18 alkyl, C2-C18 alkenyl group or C2- C6 hydroxyalkyl.

2. Suspension according to claim 1, wherein the molar ratio of recurring units (a) and (b) in polymer A, i.e. a:b, is from 97:3 to 3:

97.

3. Suspension according to any one of the preceding claims, wherein recurring units (c) are present and the molar ratio of recurring units (a), (b), and (c) in polymer A is, i.e. a:b:c, (1-30):(10-80):(10-80), preferably (5-25):(5-75):(5- 75).

4. Suspension according to any one of the preceding claims, wherein the suspension further comprises a polymer B, wherein polymer B comprises: - recurring units (a) as defined in claim 1 ; - recurring units (d) of formula (IV) ^^ wherein R7represents a hydrogen atom or methyl, R8 represents C2 to C12 alkylene group, m2 denotes a number from 1 to 30, and M4and M5represent independently a hydrogen atom, an alkali metal or an alkaline earth metal; and - recurring units (e) of formula (V)wherein R9and R11each represents independently a hydrogen atom or a methyl, R10and R12each represents independently a C2 to C12 alkylene group,m3 and m4 each represents independently a number from 1 to 30, and M6represents a hydrogen atom, an alkali metal or an alkaline earth metal.

5. Suspension according to claim 4, the molar ratio between recurring unit (a) and the sum of recurring unit (d) and recurring unit (e) in polymer B, i.e. (a):((d)+(e)), is from 5:95 to 95:5, preferably from 10:90 to 90:

10.

6. Suspension according to any one of claims 4 to 5, wherein the molar ratio between recurring unit (d) and recurring unit (e) in polymer B is from 99:1 to 4:96, preferably from 99:1 to 5:

95.

7. Suspension according to any one of claims 4 to 6, wherein the weight ratio of polymer A and polymer B is from 95:5 to 5:

95.

8. Suspension according to the preceding claims, wherein polymer A is obtainable by polymerization of a monomer (I), a monomer (II) and optionally a monomer (III), wherein - monomer (I) is represented by general formula (VII) R1 R2C CCOO(AO)nM1(VII) wherein R1, R2, AO, n and M1 are as defined in claim 1; - monomer (II) is represented by general formula (VIII):wherein M2, R3, R4, and R5 are as defined in claim 1; and - monomer (III) is represented by general formula (IX):wherein R6and M3are as defined in claim 1.

9. Suspension according to any one of the preceding claims, wherein polymer A is obtainable by: a) polymerization of: - monomer (II); wherein monomer (II) is as defined in claim 8, and - optionally monomer (III),wherein monomer (III) is as defined in claim 8; b) esterification of the polymer compound obtained in a) with at least one compound of formula (VI): HO-[AO]nM1(VI) wherein AO, n and M1are as defined in claim 110. Suspension according to any one of claims 4 to 9, wherein polymer B is obtainable by polymerization of a monomer (I), a monomer (IV) and a monomer (V), wherein - monomer (I) is as defined in claim 8; - monomer (IV) is represented by general formula (X):R7, R8, m2, M4and M5are as defined in claim 4; and - monomer (V) is represented by general Formula (XI)R9, R10, R11, R12, m3, m4and M6are as defined in claim 4.

11. Suspension according to any one of the preceding claims, wherein the mineral material is selected from a phosphate material, iron, coal, copper, carbonate-based minerals, zinc, and lead, preferably from a phosphate material and iron ores, more preferably from phosphate material.

12. A method for the preparation of a suspension according to any one of the preceding claims, wherein the method comprisesdispersing in water the mineral material, polymer A and optionally polymer B.

13. Use of the suspension according to any one of claims 1 to 11 for the transport of the mineral material present in the suspension.

14. Use of Polymer A, polymer B or mixtures thereof as defined in any one of claims 1 to 10, as dispersant for the transport of a mineral material as defined in claim 1 or 11.