METHOD FOR BENEFITING AN IRON ORE FROM A FINE-GRAINED RAW IRON ORE, COMPRISING IRON ORE AND A GANGUE MINERAL, AND USING PHOSPHORIC ACID ESTERS

Description

METHOD FOR BENEFITING AN IRON ORE FROM A FINE-GRAINED RAW IRON ORE, COMPRISING IRON ORE AND A MINERAL GAGAN, AND USE OF PHOSPHORIC ACID ESTERS

[001] The present invention relates to the beneficiation of low-grade ferrous minerals by means of wet magnetic separation. More specifically, the invention relates to enhancing the efficiency of the magnetic separation process by adding a phosphoric acid ester to the low-grade iron ore.

[002] Due to the high demand for iron oxides that has existed for many decades, sources of high-grade iron ore have been depleted or, in some areas, exhausted. As a result, great attention is currently being given to the development of technologies to recover iron oxides from iron ores containing lower-grade materials. One approach by the mining industry to meet the growing demand for high-grade iron ores is the beneficiation of low-grade slurries and fines.

[003] Most iron ore operations require beneficiation of raw ore (run-of-mine) to produce iron ore products in granular form, fine materials (sinter), and pelletizing concentrate. For iron ore beneficiation, different methods have been developed, such as gravity concentration, dense medium separation, electrostatic separation, froth flotation, and magnetic separation. Before separating the valuable ore from the gangue minerals, all these processes require comminution of the ore to liberate the individual minerals. Consequently, through crushing and grinding, the ore is generally comminuted into particles with sizes between approximately 200 µm and 40 µm. However, grinding processes produce particles with sizes ranging from approximately 200 µm to 40 µm. Petition 870260052873, dated 01 / 06 / 2026, page 5 / 117 2 / 45 mesh sizes of -20 µm and, frequently, even mesh sizes of -1 µm as a byproduct. However, most available beneficiation methods provide insufficient efficiency, especially when processing minerals that comprise a larger portion of ultrafine-sized minerals with particle sizes smaller than 20 µm. Typically, fractions with particle sizes between 200 µm and 20 µm, referred to as fines, can be directly subjected to a beneficiation process such as froth flotation or magnetic separation. Fractions comprising more than 30% by weight, and especially those comprising more than 50% by weight of particles with particle sizes smaller than 20 µm, referred to as ultrafines, are generally separated as slurries and discarded as part of the tailings – although they often contain a significant amount of iron ore.In the past, the recovery of some additional iron ores from ultrafines was not considered sufficient to justify the efforts of additional processing steps.

[004] Typically, a significant portion of extracted iron ores, i.e., 15% - 20% of raw ore (run-of-mine), ends up as slimes, i.e., as a semi-fluid paste of ultrafine particles. Currently, there is no commercial use for the slimes and, consequently, the only viable option is to dispose of them in lagoons or tailings dams for water recovery and potential future use.

[005] In addition, beneficiation processes generate, besides the valuable iron ore concentrate, enormous quantities of fine tailings with particle sizes between 200 µm and 20 µm. Although enriched in minerals of Petition 870260052873, dated 01 / 06 / 2026, page 6 / 117 3 / 45 gangue, which is harmful to iron ore products, such as silica, alumina, phosphorus, sulfur, etc., fine tailings still contain a significant amount of iron ore due to imperfections in beneficiation processes. These fine tailings are generally disposed of in similar, and sometimes the same, tailings ponds as slurries. Consequently, many iron ore slurries, low-grade iron ore tailings, and mixtures thereof are stored in tailings ponds that occupy land and pose environmental risks.

[006] In addition, enormous quantities of ferrous ores were mined and ground into particles, but subsequently deemed unsuitable for further processing due to the finding that they contained insufficient amounts of iron oxide and / or excessively high amounts of noxious materials to make their beneficiation economically viable. Many tons of these low-grade iron ores were deposited in lean ore stockpiles.

[007] Consequently, improved methods for beneficiating iron ore from slurries and tailings, as well as from other fine-grained but low-grade iron ore minerals, would improve the economics of mining operations and, concomitantly, reduce their environmental impact and thus improve the sustainability of the steel industry. In this way, the processing and utilization of slurries, tailings and other low-grade iron ore fines has become a challenging undertaking.

[008] One of the established processes in iron ore mining is magnetic separation, in which magnetic substances are separated from non-magnetic gangue or non-magnetic minerals by attraction with a magnet. The technology of Petition 870260052873, dated 01 / 06 / 2026, page 7 / 117 4 / 45 Magnetic separation allows the extraction of large volumes of magnetically susceptible iron oxides from low-grade mineral assemblages. In commercial magnetic separation units, a moving stream of dry or wet mineral particles passes through a magnetic field.

[009] The main forces acting on particles in a magnetic separator are magnetic drag, hydrodynamic drag, gravity, and friction. Each of these forces varies according to the design of the magnetic separator. While magnetic forces attract ferrimagnetic and paramagnetic particles, gravity and drag forces act against the magnetic attraction forces. For the separation of magnetic particles in a wet magnetic separator, magnetic forces must overcome hydrodynamic drag forces. However, for ultrafine magnetic particles, the liquid drag force is generally greater than the magnetic force, and especially particles with a size smaller than 10 µm are generally not effectively captured by magnetic separators. On the other hand, for particles with a size greater than 200 µm, gravity prevails and the separation efficiency also decreases.

[0010] In addition, most low-grade iron ores, besides some magnetite, typically include substantial amounts of iron oxides in the form of hematite, goethite, limonite, or other iron oxides, mixed with gangue minerals. Unlike magnetite, which is ferrimagnetic, other iron oxides, such as hematite, goethite, and limonite, are paramagnetic and therefore only weakly influenced by magnetic fields. At least in a low-intensity magnetic separator, these non-magnetic iron oxides more frequently pass into the tailings fraction along with non-ferrous impurities, resulting in loss. Petition 870260052873, dated 01 / 06 / 2026, page 8 / 117 5 / 45 of valuable iron ore.

[0011] Magnetic separation efficiency can be improved, for example, by increasing the magnetic field gradient, field intensity, and / or particle size. In a process known as wet high-intensity magnetic separation (WHIMS), high-gradient magnetic separators and superconducting magnetic separators are used. This process has proven advantageous for beneficiating fine magnetic minerals and, to some extent, paramagnetic minerals. In WHIMS processes, it is possible to beneficiate magnetite from -10 pm iron ore. However, the energy consumption of high-field magnetic separators is high, and the equipment is expensive.

[0012] An additional means of enhancing the efficiency of magnetic separation processes is to increase the size of the mineral particles. According to Svoboda et al. (Miner. Eng. 16 (2003) 785-792), with increasing particle size, the relative importance of hydrodynamic drag decreases compared to magnetic force. Increasing particle size can be achieved by agglomerating small particles, for example, by selective adsorption of a flocculant onto the desired particles of the ore suspension. Aggregation by flocculation can be carried out by binding many mineral particles together by adding a flocculant. Consequently, WHIMS applied to ultrafine magnetite particles after size increase by polymer flocculation was found to be effective in reducing the loss of fine magnetite particles.

[0013] US 4,219,408 describes a process for magnetic beneficiation of ore in which a dispersed aqueous semi-fluid slurry of the ore is mixed with a system of ferromagnetic particles. Petition 870260052873, dated 01 / 06 / 2026, page 9 / 117 6 / 45 to intensify the magnetic separation process. The aqueous semi-fluid paste is dispersed by adding dispersants such as sodium silicate, sodium hexametaphosphate, and sodium polyacrylate / sodium hexametaphosphate.

[0014] US 4,298,169 describes a method for concentrating low-grade ores in which a finely ground ore is mixed with a flocculating agent to induce selective flocculation of the desired mineral particles into ore particle cores containing residual magnetite. The flocculated ore particles are then subjected to magnetic separation. Examples of materials used to achieve selective flocculation are carbohydrates such as corn starch, potato starch, other natural and modified starches, tapioca flour, other flours, ammonium alginate, carboxymethylcellulose, cellulose xanthate, and synthetic polymerized flocculants such as polyethylene oxide, polyacrylamides and polyacrylonitriles exhibiting flocculating properties, PAMG (a polyacrylamide modified with tris-2-hydroxyaryl glyoxal), and the like.

[0015] S. Song et al. in Minerals Engineering 15 (2002) 415422 and S. Roy in Mineral Processing & Extractive Metall. Rev., 33: 170-179, 2012 demonstrated that the magnetic separation of hematite, goethite and limonite fines from iron ores can be considerably improved by selectively aggregating the fines through hydrophobic flocculation induced by sodium oleate, kerosene and a sufficient kinetic energy input.

[0016] CN11396591A teaches a novel multi-effect iron ore reverse flotation inhibitor, wherein the novel multi-effect iron ore reverse flotation inhibitor is a starch-chitosan mixture and / or a mixture of modified starch-chitosan and industrial carboxymethylcellulose.

[0017] US 2021 / 069729 teaches a process of concentration of Petition 870260052873, dated 01 / 06 / 2026, page 10 / 117 7 / 45 Ultrafine tailings (sludges) of iron minerals from iron ore processing by reverse flotation with pH between 8.5 and 10.5 with the addition of an amide-amine type collector, or additionally a mixture of the same with traditional cationic collectors (amines), in the absence of any depressant, including alternatively a high-field magnetic concentration step, which allows obtaining a concentrate with an iron content greater than 66% and SiO2+AbO3 contents less than 4%.

[0018] WO-2022 / 225492 teaches an environmentally friendly biochemical composition for use as an additive in an aqueous medium in order to increase process efficiency and resulting grade in all gravimetric and magnetic methods of wet ore concentration and classification that essentially require the use of water in the mining industry.The invention relates, in particular, to a biochemical composition of liquid concentrate for use as an additive in existing process or feed water, and a method of using the same, comprising a fermentation supernatant obtained from Saccharomyces cerevisiae culture, one or more surfactants selected from the group consisting of nonionic and anionic surfactants, preferably hydrogen peroxide or chlorine dioxide, and preservatives based on urea or other suitable preservatives, which increases process efficiency and grade recovery without requiring additional investment in facilities, in said ore beneficiation processes.

[0019] As the search for resource- and energy-efficient processes becomes more urgent, improved approaches to processing iron ore tailings, and especially iron ore slurries and fines, are needed. Consequently, there was a need for a method to Petition 870260052873, dated 01 / 06 / 2026, page 11 / 117 8 / 45 Enhanced beneficiation for fine iron ores, and especially fine iron ores exhibiting D50 particle sizes of, for example, 200 μm and below, as well as for ultrafine iron ores exhibiting D50 particle sizes of, for example, 20 μm and below. Since the mass of high-grade iron ore recovered is of great economic importance to mining operations, a process for beneficiating iron ore that allows the extraction of additional quantities of valuable iron ore from the raw ore and / or a better recovery rate of the iron contained in the raw ore would be highly valued. In parallel, the silicate content of the recovered iron ore concentrate should be reduced or at least maintained; that is, the selectivity between iron ore and contaminants, for example, silicate, should be improved or at least maintained.Furthermore, the volume of water required for the process must be minimized, and its contaminant content must be as low as possible for final disposal. Since a mining plant frequently processes several types of iron ore in parallel in its daily operations, this beneficiation method must be suitable for a variety of different grades of iron ore minerals. In addition, the environmental impact of the process must be minimized, for example, through the use of additives based on renewable raw materials and / or biodegradable additives.

[0020] Surprisingly, it was found that the recovery rate of iron from fine-grained iron ore minerals in a magnetic separation process can be improved by adding a phosphoric acid ester to the aqueous semi-fluid slurry of fine-grained iron ore mineral before subjecting the aqueous semi-fluid slurry to the process. Petition 870260052873, dated 01 / 06 / 2026, page 12 / 117 9 / 45 Magnetic separation. This finding is especially valid for low-grade, fine-grained iron ore minerals. Concomitantly, the quartz content of the recovered iron ores is reduced or at least maintained. This allows for the extraction of additional valuable iron ore from slurries, tailings, and other low-grade fines that would otherwise be useless, i.e., it allows for enhanced mass recovery of the iron ore. Unexpectedly, the presence of surface-active phosphoric acid esters in the concentrated semi-fluid iron ore slurry obtained from the magnetic separation process does not interfere with the subsequent recovery of iron ore by conventional flocculation and sedimentation methods.

[0021] In a first aspect, the present invention provides the use of a phosphoric acid ester to enhance the recovery rate of iron from an aqueous semi-fluid slurry of fine-grained crude iron ore comprising an iron ore and a gangue mineral in a magnetic separation process, wherein the phosphoric acid ester comprises a phosphoric acid monoester according to Formula (I), a phosphoric acid diester according to Formula (II) or a mixture of phosphoric acid monoester (I) and phosphoric acid diester (II), R1 OA--O . m THE P--0“ Xn+ O” n / 2 (I) (II) Petition 870260052873, dated 01 / 06 / 2026, p. 13 / 117 10 / 45 in which: R1 and R2 are identical or different and, independently of each other, are selected from the group consisting of alkyl groups, alkenyl groups, acyl groups, and optionally substituted phenyl groups, having from 6 to 40 carbon atoms; A is an alkylene group containing 2 to 6 carbon atoms; X is hydrogen or a cation with valence n; n is 1, 2, or 3; em is 0 or an integer from 1 to 20.

[0022] In a second aspect, the present invention provides a method for beneficiating iron ore from a fine-grained raw iron ore comprising iron ore and a gangue mineral, in which: (i) fine-grained raw iron ore, comprising iron ore and a gangue mineral, is dispersed in an aqueous phase to provide an aqueous semi-fluid paste; (ii) this aqueous semi-fluid paste is mixed with at least one phosphoric acid ester; (iii) the treated aqueous semi-fluid slurry is subjected to magnetic separation means to obtain a fraction of the fine-grained iron ore semi-fluid slurry that is enriched in iron ore and exhausted in gangue mineral; and (iv) a concentrated iron ore is extracted from the fraction of the iron ore semi-fluid slurry that is being enriched in iron ore.

[0023] In a third aspect, the present invention provides a method of enhancing the recovery of iron ore mass from an aqueous semi-fluid slurry of fine-grained raw iron ore, this method comprising iron ore and Petition 870260052873, dated 01 / 06 / 2026, page 14 / 117 11 / 45 a gangue mineral, in a magnetic separation process, wherein a phosphoric acid ester is added to the aqueous semi-fluid slurry before subjecting it to a magnetic separation process, and wherein the addition of the phosphoric acid ester effects the separation of a concentrated fraction of iron ore exhibiting a high iron content from a fraction of gangue tailings exhibiting a reduced iron content, both in relation to the raw iron ore, wherein the phosphoric acid ester comprises a phosphoric acid monoester according to Formula (I), a phosphoric acid diester according to Formula (II) or a mixture of phosphoric acid monoester (I) and phosphoric acid diester (II). R1 OA--O . m THE P—0“ Xn+ On / 2 (I) (II) in which: R1 and R2 are identical or different and, independently of each other, are selected from the group consisting of alkyl groups, alkenyl groups, acyl groups, and optionally substituted phenyl groups, having from 6 to 40 carbon atoms; A is an alkylene group that has 2 to 6 carbon atoms; X is hydrogen or a cation with valence n; n is 1, 2, or 3; em is 0 or an integer from 1 to 20. Petition 870260052873, dated 01 / 06 / 2026, p. 15 / 117 12 / 45

[0024] In a fourth aspect, the present invention provides a method of intensifying the recovery rate of iron from an aqueous semi-fluid slurry of fine-grained raw iron ore, which method comprises iron ore and a gangue mineral, in a magnetic separation process, wherein a phosphoric acid ester is added to the aqueous semi-fluid slurry before subjecting it to a magnetic separation process, and wherein the addition of the phosphoric acid ester effects the separation of a concentrated fraction of iron ore having a high iron content from a fraction of gangue tailings having a reduced iron content, both relative to the raw iron ore, wherein the phosphoric acid ester comprises a phosphoric acid monoester according to Formula (I), a phosphoric acid diester according to Formula (II) or a mixture of phosphoric acid monoester (I) and phosphoric acid diester (II). R1 OA--O . m DUST THE Xn+n / 2 (I) (II) in which: R1 and R2 are identical or different and, independently of each other, are selected from the group consisting of alkyl groups, alkenyl groups, acyl groups, and optionally substituted phenyl groups, having from 6 to 40 carbon atoms; A is an alkylene group that has 2 to 6 Petition 870260052873, dated 01 / 06 / 2026, p. 16 / 117 13 / 45 carbon atoms; X is hydrogen or a cation with valence n; n is 1, 2, or 3; em is 0 or an integer from 1 to 20.

[0025] In the context of this patent application, the term iron ore refers to all ferrimagnetic and paramagnetic iron ores that are attracted by a magnet. It refers especially to oxide ferrimagnetic and paramagnetic iron ores that are attracted by a magnet. Consequently, the term iron ore encompasses iron oxides and oxyhydroxides, including magnetite, hematite, martite, specularite, goethite, limonite, and any mixture thereof. Such iron ores generally contain small amounts of contaminants, such as silicates. Furthermore, the term iron ore also encompasses iron ores with mixed oxide metals, comprising iron and at least one other metal. Preferably, at least one other metal is a transition metal from the 4th period of the Periodic Table of Elements.More preferably, at least one other metal is selected from the group consisting of titanium, vanadium, chromium, manganese, zinc, and any combination thereof. Other particularly preferred metals are chromium and titanium. Preferred iron ores with mixed oxide metals include, but are not limited to, titanomagnetites, which form a range of compositions with the formulas Fe3-x TiO4 with 0 < x < 1, and titanohematites, including, for example, ilmenite (FeTiO3). Additional iron ores with mixed oxide metals that may benefit from the various aspects of the invention include, but are not limited to, chromite, franklinite, jacobsite, and any mixtures thereof. Typical contaminants that must be removed from iron ores with mixed oxide metals are silicates such as quartz, albite, and talc. Petition 870260052873, dated 01 / 06 / 2026, p. 17 / 117 14 / 45

[0026] The term iron ore mineral refers to mineral assemblies comprising iron ore and one or more gangue minerals. This term includes compositions that resemble the mineralogy of the desired mineral in a low-grade ore deposit, as well as the composition of slurries / tailings that are to be reworked. Similarly, the terms raw ore and raw iron ore refer to an iron ore mineral that is used as starting material for the various aspects of the present invention. These terms encompass fine iron ore minerals having a D50 particle size of, for example, less than 500 µm, preferably having a D50 particle size less than 200 µm (fines) and, more preferably, a D50 particle size less than 106 µm, and ultrafine iron ore minerals having a D50 particle size of, for example, 20 µm and below (ultrafines), including slurries.Similarly, the terms iron ore mineral, raw ore, and raw iron ore encompass mixtures of fines with ultrafines in any ratio. Preferred mixtures comprise fines and ultrafines in a weight ratio of 1:99 to 99:1, and more preferably in a weight ratio of 5:95 to 95:5, such as, for example, in a weight ratio of 1:95 to 99:1, or of 1:99 to 95:1. Consequently, these terms encompass mixtures of fines and ultrafines resulting from the storage of slurries and tailings in the same tailings pond.

[0027] In the context of this patent application, the term mass recovery means the percentage of concentrated iron ore relative to the total mass of raw iron ore. Mass recovery Y can be calculated using the Formula F = - * 100 = — * 100 , F cr where: C = dry mass of concentrate from separation Petition 870260052873, dated 01 / 06 / 2026, page 18 / 117 15 / 45 magnetic; F = dry mass of raw ore fed for magnetic separation; f = Fe content fed; c = concentrated Fe content; er = Fe content in tailings.

[0028] In the context of this patent application, the term iron recovery rate means the weight ratio of iron recovered in the iron ore concentrate obtained from the magnetic separation process to the iron content of the raw iron ore.

[0029] The terms enhanced recovery rate, improved recovery rate, as well as intensification of magnetic separation of iron ores from gangue mineral mean a higher recovery rate of iron obtained in a magnetic separation process, including the features of this invention (i.e., in the presence of a phosphoric acid ester) compared with the same process conducted without the features of this invention (i.e., in the absence of a phosphoric acid ester).

[0030] The iron recovery rate can be calculated using the formula c fí = y *f

[0031] In the context of this patent application, the term gangue mineral refers to a variety of minerals that surround or are intimately mixed with the desired iron ore in the raw iron ore. This includes silica, alumina, phosphorus, and sulfur in different forms. While valuable iron ores are ferrimagnetic or paramagnetic and therefore attracted by a magnet, most gangue minerals are diamagnetic and therefore exhibit an inherently low magnetic attractiveness. Petition 870260052873, dated 01 / 06 / 2026, page 19 / 117 16 / 45

[0032] The terms beneficiate, beneficiation and beneficiated refer to an ore enrichment process in which the concentration of the desired metal in the ore increases as the process progresses.

[0033] For the purposes of this disclosure, the terms low-grade iron ore and low-grade iron-containing mineral refer to materials that are composed of a mixture of one or more iron ores and substantial amounts of one or more non-ferrous mineral impurities, commonly one or more of quartz, flint, alumina, carbonate or the like.

[0034] For iron ores comprising iron essentially in the form of oxide or oxyhydroxide, low-grade iron ore means an iron content of 10 to 53% by weight and preferably 15 to 50% by weight, such as, for example, 10 to 50% by weight or 15 to 53% by weight. For iron ores of mixed oxide metals comprising iron and another metal, and specifically comprising iron and another transition metal of the 4th period of the Periodic Table of Elements, low-grade iron ore means an iron and other metal content of 10 to 53% by weight and preferably 15 to 50% by weight, such as, for example, 10 to 50% by weight or 15 to 53% by weight.

[0035] Low-grade iron ores and low-grade iron-bearing minerals include stockpiled tailings and lean ores, together with lean ores in their natural state (i.e., unmined and / or unmilled), regardless of whether or not they include any amount of magnetite, and whether they include hematite, goethite, iron oxides other than hematite and goethite, or both. An example of low-grade iron ore is the iron ore commonly referred to as taconite, an iron-bearing sedimentary rock, typically exhibiting an iron oxide content of about Petition 870260052873, dated 01 / 06 / 2026, page 20 / 117 17 / 45 15% to about 40%, and only part of it is magnetite, with the remainder being non-ferrous impurities.

[0036] In the context of this patent application, the term fine granules means a particle size D50 smaller than 500 µm, preferably a particle size D50 smaller than 200 µm, more preferably a particle size D50 smaller than 106 µm, and especially a particle size D50 smaller than 20 µm. The particle size D50 represents the average value of the particle size distribution (D50; median diameter), that is, the diameter of the particles that are 50% by weight of the mass of a sample smaller and 50% by weight of the mass of a sample larger. The particle size distribution can be determined, for example, by laser diffraction according to ASTM B822-10, a technique based on the analysis of the diffraction pattern produced when particles are exposed to a monochromatic light beam.

[0037] In a preferred embodiment, R1 and R2, independently of each other, are an alkyl, alkenyl or acyl group having from 6 to 24 and, especially preferably, from 8 to 18 carbon atoms, such as, for example, from 6 to 18 carbon atoms, or from 8 to 40 carbon atoms, or from 8 to 24 carbon atoms. R1 and R2 may be the same or different. In a preferred embodiment, both are the same.

[0038] Preferred phosphoric acid esters of Formulas (I) and (II) can be obtained by reacting a phosphating agent with an alcohol. Alcohols suitable for the synthesis of the phosphate esters of Formulas (I) and / or (II) include fatty alcohols, fatty alcohol alkoxylates, and fatty acid alkoxylates.

[0039] Typically, the phosphating agent is an activated phosphorus derivative. The phosphoric acid ester products thus obtained are mixtures of monoalkyl phosphate (monoester), phosphate of Petition 870260052873, dated 01 / 06 / 2026, p. 21 / 117 18 / 45 dialkyl (diester) and trialkyl phosphate (triester) in varying amounts. The reaction products often contain small amounts of residual alcohol and residual phosphoric acid, respectively, from their activated derivative. The proportion of phosphoric acid ester in monoester, diester, and triester products can be controlled, for example, by the molar ratio of the reagents. In a preferred embodiment, the reaction product of an alcohol with an activated phosphorus derivative is used as such, i.e., without further purification.

[0040] In a preferred embodiment, the molar ratio of phosphoric acid monoester (I) to phosphoric acid diester (II) is 1:10 to 10:1. More preferably, the molar ratio is 1:5 to 5:1, as well as 1:5 to 10:1, or 10:1 to 1:5. In a further preferred embodiment, the proportion of mono and diester in a phosphoric acid ester reaction product is at least 50 mol%, more preferably 60 to 99 mol%, and especially preferably between 65 and 95 mol%, such as 50 to 95 mol%, or 50 to 99 mol%, or 60 to 95 mol%, or 65 to 99 mol%, based on all phosphoric acid esters present.In a further preferred embodiment, the proportion of phosphoric acid triester is preferably below 40 molar percent, more preferably from 0.1 to 25 molar percent, and especially preferably from 1 to 10 molar percent, such as from 0.1 to 40 molar percent, or from 0.1 to 25 molar percent, or from 1 to 40 molar percent, or from 1 to 25 molar percent, based on all phosphoric acid esters present.

[0041] The most common phosphating agents used for the synthesis of phosphoric acid esters are phosphoric anhydride (P2O5), polyphosphoric acid (H4P2O7), phosphorus oxychloride [P(O)Ch], orthophosphoric acid (H3PO4), and pyrophosphoric acid. Preferably, the molar ratio between the phosphating agent and the alcohol is between 1:0.5 and 1:4. Petition 870260052873, dated 01 / 06 / 2026, p. 22 / 117 19 / 45 more preferably between 1:1 and 1:2, based on the phosphorus content of the phosphating agent. The means for manufacturing phosphoric acid esters are known to those skilled in the art.

[0042] In a first embodiment, R1 and R2 are alkyl or alkenyl groups, where ε is 0. Such esters are derived from fatty alcohols. The preferred fatty alcohols have the general formulas R3-OH and R4-OH, wherein R3 and R4 are identical or different and, independently of each other, are selected from alkyl and alkenyl groups having from 6 to 40 carbon atoms, more preferably having from 6 to 24 carbon atoms and especially preferably having from 8 to 18 carbon atoms, such as, for example, from 6 to 18 carbon atoms, or from 8 to 40 carbon atoms, or from 8 to 24 carbon atoms. The preferred fatty alcohols of formulas R3-OH and R4-OH may be of synthetic or natural origin.

[0043] Preferred fatty alcohols of General Formulas R3-OH and R4OH may be primary, secondary, tertiary alcohols or mixtures thereof, i.e., the hydroxyl group, -OH, may be attached to a saturated carbon atom that has one (primary alcohol), two (secondary alcohol) or three (tertiary alcohol) other carbon atoms attached to it. In a preferred embodiment, the alcohol is a primary alcohol.

[0044] In a preferred embodiment, the fatty alcohols R3-OH and R4-OH alcohols are of natural origin. Preferred naturally occurring alcohols are caproic alcohol, caprylic alcohol, capric alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, palmitoleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, petrosellinyl alcohol, linoleic alcohol, linolenyl alcohol, elaeostearyl alcohol, arachyl alcohol, gadoleyl alcohol, behenyl alcohol, erucill alcohol, brassidyl alcohol, and mixtures thereof. These may be Petition 870260052873, dated 01 / 06 / 2026, p. 23 / 117 20 / 45 derived from oils and fats by hydrolysis and subsequent reduction of the fatty acids thus obtained. More preferred fatty alcohols may be derived, for example, from coconut oil, soybean oil, sunflower oil, palm oil, palm kernel oil, tallow fat, olive oil, rice oil, corn oil, peanut oil and mixtures thereof.

[0045] In a further preferred embodiment, fatty alcohols R3-OH and R4-OH are synthetic. Preferred synthetic fatty alcohols may be derived from lower olefin oligomers having 2 to 5 carbon atoms, and preferably 2 to 4 carbon atoms, such as ethylene, propylene, and butylene. Examples of preferred lower olefin oligomers are essentially linear α-olefins having 4 to 20, more preferably 6 to 24, and especially preferably 8 to 18 carbon atoms, such as tripropylene, tetrapropylene, pentapropylene, diisobutylene, tributylene, triisobutylene, tetrabutylene, tetraisobutylene, pentapropylene, and the like. Methods for converting alkenes into alcohols are known to those skilled in the art.Additional examples of synthetic alcohols featuring branched alkyl radicals include hexanol, 2-ethylhexanol, 4-methylpentan-2-ol, octan-2-ol, 6-methylheptane-3-ol, nonanol, iso-nonanol, 2,6-dimethylheptane-4-ol, 2-propylheptane, isodecanol, undecanol, 2,6,8-trimethyl-4-nonanol, iso-tridecanol, isoheptadecanol, and the like.

[0046] In a further preferred embodiment, R1 and R2, independently of each other, are an acyl group where is an integer from 1 to 20. In this embodiment, the alcohol used to synthesize the phosphate esters of Formulas (I) and / or (II) is a fatty acid alkoxylate. The preferred acyl groups R1 and R2 have the General Formulas R5-C(O)- and R6-C(O)-, where R5 and R6 are identical or Petition 870260052873, dated 01 / 06 / 2026, p. 24 / 117 21 / 45 different, and independently of each other, are selected from alkyl or alkenyl groups having from 5 to 39, more preferably from 5 to 23, and especially preferably from 7 to 17 carbon atoms, such as, for example, from 5 to 17 carbon atoms, or from 7 to 39 carbon atoms, or from 7 to 23 carbon atoms.

[0047] The preferred acyl groups R5-C(O)- and R6-C(O)- are derived from fatty acids. The preferred fatty acids may be of synthetic or natural origin. Preferred fatty acids of natural origin include caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, myristoleic acid, palmitic acid, palmitoleic acid, stearic acid, isostearic acid, oleic acid, arachidic acid, elaidic acid, petroselinic acid, linolic acid, linolenic acid, eleostearic acid, arachidonic acid, gadoleic acid, behenic acid, erucic acid, brassidic acid, and mixtures thereof. These may be derived from oils and fats by hydrolysis. The most preferred fatty acids can be derived, for example, from coconut oil, soybean oil, sunflower oil, palm oil, palm kernel oil, tallow, olive oil, rice oil, corn oil, and peanut oil.

[0048] Synthetic fatty acids are equally suitable. Examples of synthetic fatty acids are branched fatty acids, such as isoundecanoic acid, isotridecanoic acid, versatile acids, and mixtures thereof.

[0049] Preferred alkyl and alkenyl groups R3 and R4 of fatty alcohols and fatty alcohol alkoxylates, as well as alkyl and alkenyl groups R5 and R6 of fatty acid alkoxylates, may be linear, branched, or cyclic. In a first preferred embodiment, the alkyl and alkenyl groups of fatty alcohols and fatty acids of natural origin are predominantly linear. In a second preferred embodiment, the alkyl groups of fatty alcohols and fatty acids Petition 870260052873, dated 01 / 06 / 2026, p. 25 / 117 22 / 45 synthetic fatty acids are predominantly branched. The preferred alkenyl groups have one, two, or three C=C double bonds. The most preferred alkenyl groups have one C=C double bond.

[0050] In a further preferred embodiment, the alcohol used for manufacturing the phosphoric acid esters of Formulas (I) and (II) is an alkoxylated fatty alcohol. The preferred alkoxylated fatty alcohols have the General Formulas R3-[OA]m-OH and R4-[OA]m-OH, where R3, R4, A and m have the meanings given above. These can be derived from a fatty alcohol of Formula R3-OH or R4-OH by means of alkoxylation.

[0051] In a further preferred embodiment, R1 and R2 are, independently of each other, an optionally substituted phenyl group where is an integer from 1 to 20. In this embodiment, the alcohol used to synthesize the phosphate esters of Formulas (I) and / or (II) is the alkoxylate of an optionally substituted phenol. The preferred optionally substituted aryl groups have General Formulas R7-OH and R8-OH, in which R7 and R8 are identical or different and, independently of each other, are selected from phenol and phenol substituted by one or more, such as 1, 2 or 3 substituents. R7 and R8 have from 6 to 40 carbon atoms, more preferably from 6 to 24 carbon atoms and, especially preferably, from 8 to 18 carbon atoms, such as, for example, from 6 to 18 carbon atoms, or from 8 to 40 carbon atoms, or from 8 to 24 carbon atoms. Preferred substituents for the aryl group are alkyl, alkenyl, alkylphenyl and alkenylphenyl groups.In a preferred embodiment, the alkyl substituents have from 1 to 36, preferably from 2 to 20, and especially preferably from 4 to 14 carbon atoms, such as, for example, from 1 to 20 carbon atoms, or from 1 to 18 carbon atoms, or from 2 to 36 carbon atoms. Petition 870260052873, dated 01 / 06 / 2026, p. 26 / 117 23 / 45 from 2 to 14 carbon atoms, or from 4 to 36 carbon atoms, or from 4 to 20 carbon atoms. The alkyl groups can be linear or, if they contain 3 or more carbon atoms, they can be branched. Preferred alkylphenols of formulas R7-OH and R8-OH have one alkyl group per phenol. An example of a phenol that is substituted by an alkenylphenyl group is tristyrylphenol.

[0052] In a further preferred embodiment, the phosphoric acid ester of Formulas (I) and / or (II) comprises a mixture of different esters derived from at least two different alcohols selected from the fatty alcohol groups of Formulas R3-OH and / or R4-OH; fatty alcohol alkoxylates of Formulas R3[-OA]m-OH and / or R4[-OA]m-OH; fatty acid alkoxylates of General Formulas R5C(O)-[-OA]m-OH and / or R6-C(O)-[-OA]m-OH; and optionally substituted alkoxylated phenols of General Formulas R7[-OA]m-OH and / or R8[-OA]m-OH. The proportion of each ester in the mixture can be from 1 to 99 molar percent, preferably from 5 to 95 molar percent, and especially preferred from 10 to 90 molar percent, for example, from 1 to 95 molar percent, or from 1 to 90 molar percent, or from 5 to 99 molar percent, or from 5 to 90 molar percent, or from 10 to 99 molar percent, or from 10 to 95 molar percent.

[0053] In a preferred embodiment, A is an alkylene group having 2 or 3 carbon atoms and, especially preferably, having 2 carbon atoms. Consequently, preferred alkoxylates may be ethoxylates, propoxylates and mixtures thereof. The degree of alkoxylation is given by the subscript m.

[0054] In a preferred embodiment, m is an integer from 1 to 20, more preferably from 2 to 15 and especially preferably from 3 to 10, such as, for example, from 1 to 15, or from 1 to 10, or from 2 to 20, or from 2 to 10, or from 3 to 20, or from 3 to 15. In this embodiment, the phosphoric acid ester of Formulas (I) and / or (II) may be the product of the reaction of a Petition 870260052873, dated 01 / 06 / 2026, p. 27 / 117 24 / 45 phosphating agent and an alkoxylated fatty alcohol or an alkoxylated fatty acid.

[0055] In a first preferred embodiment, X is hydrogen and n is 1. This refers to partial esters of phosphoric acid having one or two acid groups. In a further preferred embodiment, the Xn+ cation in Formulas (I) and (II) is selected from metal ions, NH4+, and organic ammonium ions derived from amines and / or alkanolamines. Preferably, n is 1 or 2 and, especially preferably, n is 1. The preferred metal ions are alkali and alkaline earth metal ions, in particular Na+, K+, Ca2+, and Mg2+. The preferred organic ammonium salts are derived from primary and secondary alkylamines having from 1 to 30 carbon atoms and, especially preferably, having from 4 to 22 carbon atoms. Additional preferred amines are alkanolamines, such as, for example, monoethanolamine, diethanolamine, and triethanolamine. Preferred cations include hydrogen, Na+, K+, and NH4+.

[0056] Preferably, the amount of phosphoric acid ester added to the aqueous semi-fluid iron ore paste in the various aspects of the invention is from 1 ppm to 5,000 ppm relative to the mass of the raw iron ore, more preferably from 10 to 1,000 ppm and especially preferably from 20 to 500 ppm, such as, for example, from 1 to 1,000 ppm, or from 1 to 500 ppm, or from 10 to 5,000 ppm, or from 10 to 500 ppm, or from 20 to 5,000 ppm, or from 20 to 1,000 ppm.

[0057] In the context of this disclosure, the term aqueous phase includes distilled water, fresh water, tap water, recycled process water, brackish water and the like. The aqueous phase functions as the continuous phase of the aqueous semi-fluid slurry. Preferably, the aqueous phase represents 20 to 90 percent by weight and, more preferably, 30 to 70 percent by weight of the aqueous semi-fluid slurry that is subjected to magnetic separation. Consequently, Petition 870260052873, dated 01 / 06 / 2026, p. 28 / 117 25 / 45 in a preferred embodiment, the aqueous semi-fluid paste contains 80 to 20% by weight and, more preferably, 70 to 30% by weight of solids when undergoing magnetic separation.

[0058] The aqueous phase may contain dissolved inorganic and / or organic salts. The salts may be intentionally added or may be dissolved from the minerals. Preferred inorganic salts comprise a cation of one or more alkali metals, alkaline earth metals, main group metals, and transition metals. Preferred anions are halides such as chloride, bromide, and iodide, sulfate, carbonate, nitrate, phosphate, and the like. In a preferred embodiment, the aqueous phase contains one or more of NaCl, Na2CO3, NaHCOa, KCl, KHCO3, K2CO3, MgCk, CaCl2. In a further preferred embodiment, the aqueous phase contains at least one additional additive, for example, to control bacterial growth, reduce the freezing point, disperse fine and / or ultrafine particles, selectively precipitate ions, and the like.

[0059] The pH of the aqueous semi-fluid paste can vary over a wide range. In preferred embodiments, the pH of the aqueous semi-fluid paste ranges from 6 to 11, and more preferably from 6.5 to 10, and especially preferably from 7 to 9, such as, for example, from 6 to 10, or from 6 to 9, or from 6.5 to 11, or from 6.5 to 9, or from 7 to 11, or from 7 to 10. If necessary, the pH of the aqueous semi-fluid paste can be adjusted by adding acid or base. The pH can be reduced, if necessary, by adding an acid, such as, for example, HCl, H2SO4, HNO3, H3PO4 and the like. The pH of the aqueous phase can be increased, if necessary, by adding a base, such as, for example, NaOH, Na2CO3, KOH, K2CO3, ammonium hydroxide, sodium silicate and the like.

[0060] The different aspects of the invention are especially advantageous for the beneficiation of fine-grained iron ores, such as slurries and other fines. However, ore materials of Petition 870260052873, dated 01 / 06 / 2026, p. 29 / 117 26 / 45 coarser grit can also be processed, but may require additional comminution to optimize iron oxide recovery. It is evident that in the separation of any ore by magnetic or other forces, the ore must be crushed and ground to a sufficiently fine quantity to liberate the valuable minerals from the gangue, and also that the degree of fineness required in the crushing and grinding process depends on the physical characteristics of the ore.

[0061] The various aspects of the present invention are particularly advantageous in wet magnetic separation processes. In wet magnetic separation processes, an aqueous semi-fluid slurry of a ground mineral is subjected to a magnetic field. This is accomplished by flowing a stream of the aqueous semi-fluid slurry of fine-grained mineral over a magnetic surface. The gangue is washed from the magnetic surface and discarded. The retained magnetic minerals are recovered and concentrated by removing the magnetic surface. When desired, the magnetically separated concentrate can be further concentrated by conventional beneficiation methods.

[0062] Commercial magnetic separation units apply continuous separation processes to a stream of moving particles passing through a low or high magnetic field. A variety of different wet magnetic separators are known and commercially available, for example, drum, cross-belt, roller, high-gradient magnetic separation (HGMS), high-intensity magnetic separation (HIMS), and low-intensity magnetic separation (LIMS) types. A drum separator consists of a non-magnetic drum fitted with three to six permanent magnets. It is composed of ceramic or rare-earth magnetic alloys on the inner periphery. The drum rotates in uniform motion over a moving wet feed stream. The minerals Petition 870260052873, dated 01 / 06 / 2026, page 30 / 117 27 / 45 magnetic particles are captured by rotating magnets and fixed to the outer surface of the drum. As the drum moves upwards, the concentrate is compressed, dehydrated, and discharged, leaving the gangue in the reject compartment. More specialized separators used in heavy media plants today are, for example, simultaneous single-drum wet magnetic separators, countercurrent single-drum wet magnetic separators, and double-drum separators.

[0063] For magnetic separation, the fine-grained particulate mineral assemblage is suspended in an aqueous phase. The resulting aqueous semi-fluid slurry is passed through a magnetic separator that produces a magnetic field of sufficiently high intensity to separate the mineral assemblage into a concentrate fraction having a higher iron oxide concentration than the mineral assemblage and a tailings fraction having a lower iron oxide concentration than the mineral assemblage. Due to the strong magnetic field required to influence the trajectories of the iron oxides, which are only weakly susceptible to magnetic fields, and the need to suspend the low-grade mineral assemblages in water to form a semi-fluid slurry before passing through the magnetic field, the devices used in this type of process have come to be called high-intensity wet magnetic separation devices, or WHIMS devices.

[0064] In a preferred embodiment, the magnetic field strength used for the magnetic separation process is from 0.5 T to 3.0 T, more preferably from 0.8 T to 2.0 T, and especially preferably from 1.0 T to 1.8 T.

[0065] By the method according to the third aspect of the invention, the recovery of the iron ore mass is increased Petition 870260052873, dated 01 / 06 / 2026, p. 31 / 117 28 / 45 preferably by at least 1% by weight relative to the mass recovery obtained in the same process in the absence of phosphoric acid ester. More preferably, the iron ore mass recovery is increased by at least 2.5% by weight and, especially preferably, by at least 4% by weight relative to the recovery rate obtained in the same process in the absence of phosphoric acid ester.

[0066] By the method according to the fourth aspect of the invention, the iron recovery rate is preferably increased by at least 1% by weight relative to the iron recovery rate obtained in the same process in the absence of the phosphoric acid ester. More preferably, the iron recovery rate is increased by at least 2.5% by weight and, especially preferably, by at least 4% by weight relative to the iron recovery rate obtained in the same process in the absence of the phosphoric acid ester.

[0067] Typically, the fraction of iron ore concentrate obtained from the magnetic separation process is a semi-fluid aqueous slurry or, at least, a wet slurry. To obtain a marketable dry iron ore concentrate, dewatering or solid / liquid separation is necessary. Dewatering can be carried out by successive steps of (1) sedimentation or thickening, (2) filtration, and (3) thermal drying. In a preferred embodiment, flocculants are added to the semi-fluid aqueous slurry to facilitate solid / liquid separation and accelerate water clarification. Examples of preferred flocculants are aluminum polychloride and ferric chloride.

[0068] Sedimentation or thickening can be achieved by natural gravity decantation of the solid portion of the concentrated semi-fluid paste. This can occur by continuously feeding the semi-fluid paste into a cylindrical thickening tank. After the Petition 870260052873, dated 01 / 06 / 2026, page 32 / 11729 / 45 sedimentation, a clear liquid overflows from the tank and a thickened semi-fluid slurry that settles at the bottom is removed as underflow. The effectiveness of the thickening process can be evaluated by the solids content of the underflow and / or the turbidity of the overflow. A good separation result is indicated by a high solids content in the underflow and low turbidity in the overflow. Frequently, an overflow turbidity below 200 NTU (Nephelometric Turbidity Units) and especially below 100 NTU is considered a satisfactory separation, which allows the overflow to be reused in mining processes such as comminution and / or beneficiation. Turbidity can be determined by nephelometry with a turbidimeter, according to EPA method 180.1, or according to ISO 7027.These methods determine the concentration of suspended particles in a water sample by measuring the intensity of incident light scattered at right angles (90°). The scattered light is captured by a photodiode, which produces an electronic signal that is converted into a turbidity value and then into NTUs by comparison with the intensity of light scattered by a standard semi-fluid reference paste or a standard reference suspension. The higher the intensity of scattered light, the greater the turbidity.

[0069] In a preferred embodiment, a flocculant is added to the concentrated iron ore fraction obtained from the magnetic separation process to accelerate the sedimentation process. Since many flocculants are amphiphilic compounds (surfactants), their presence can interfere with the sedimentation of solids and lead to highly turbid overflow. Surprisingly, the presence of a phosphoric acid ester, according to the invention, in the concentrated iron ore fraction does not interfere with the process. Petition 870260052873, dated 01 / 06 / 2026, page 33 / 117 30 / 45 of sedimentation. Frequently, the presence of a phosphoric acid ester, according to the invention, even facilitates the sedimentation process, that is, it further accelerates sedimentation.

[0070] The different aspects of the invention are particularly advantageous for beneficiation of paramagnetic iron oxides, such as hematite and goethite, as well as for beneficiation of iron ores with mixed oxide metals, such as ilmenite and chromite, from fine-grained iron ore minerals. Similarly, the different aspects of the invention are particularly advantageous for beneficiation of paramagnetic iron ores having an average particle size distribution D50 of less than 500 µm, preferably having a D50 of less than 200 µm, more preferably having a D50 of less than 106 µm, and especially for those having a D50 equal to or less than 20 µm.Similarly, they are advantageous for beneficiating paramagnetic iron ores comprising more than 25% by weight, often also for beneficiating paramagnetic iron ores comprising more than 40% by weight, and sometimes also for paramagnetic iron ores comprising more than 50% by weight of particles that have a size smaller than 20 µm.

[0071] As will be recognized by those skilled in the art, the term "separated," as used in this report, is not intended to require the complete separation of iron oxides from gangue materials. The term refers instead to the separation of a low-grade, fine-grained iron ore mineral into a fraction having a higher concentration of iron oxides and a lower concentration of gangue materials (referred to in this report as the concentrated fraction) and a fraction having a lower concentration of iron oxides and a higher concentration of gangue materials. Petition 870260052873, dated 01 / 06 / 2026, page 34 / 117 31 / 45 gangue materials (referred to in this report as the tailings fraction), both in relation to the composition of the low-grade, fine-grained initial iron ore mineral. In a preferred embodiment, the recovered concentrate fraction has an iron content of at least 1% by weight, more preferably at least 7% by weight, and especially preferably at least 12% by weight higher than that of the fine-grained initial mineral.

[0072] In a further preferred embodiment, the phosphoric acid ester according to the invention can be used in combination with a fatty acid or a fatty acid salt. Similarly, the methods according to the second, third and fourth aspects of the invention can be practiced in the presence of a fatty acid in addition to the phosphoric acid ester. Frequently, this results in a synergistic improvement in the recovery of iron ore mass and / or the iron recovery rate. This can be achieved by using a concentrate comprising the phosphoric acid ester and a fatty acid. Alternatively, the phosphoric acid ester and the fatty acid can be added to the semi-fluid mineral slurry separately, but prior to the magnetic separation process.

[0073] Preferred fatty acids for further enhancement of iron ore mass recovery and / or iron recovery rate have 6 to 36, and more preferably 10 to 24 carbon atoms. Examples of fatty acids include caproic acid, caprylic acid, neononanoic acid, capric acid, neodecanoic acid, lauric acid, myristic acid, myristoleic acid, palmitic acid, palmitoleic acid, stearic acid, isostearic acid, oleic acid, arachidic acid, elaidic acid, petroselinic acid, linolic acid, linolenic acid, eleostearic acid, arachidonic acid, gadoleic acid, behenic acid, erucic acid, brassidic acid, and mixtures thereof. More preferred fatty acids, and especially Petition 870260052873, dated 01 / 06 / 2026, page 35 / 117 32 / 45 mixtures of fatty acids can be derived from triglycerides of vegetable or animal origin, such as, for example, coconut oil, soybean oil, sunflower oil, palm oil, palm kernel oil, tallow, olive oil, rice oil, corn oil, peanut oil, and mixtures thereof. Preferred fatty acids can be derived from oils and fats by hydrolysis. Synthetic fatty acids are similarly suitable. Examples of synthetic fatty acids are the same as listed above, but are obtained synthetically, for example, by oligomerization of lower olefins such as ethylene, propylene, and / or butylene, and subsequent oxidation of the oligo-olefin thus obtained. Other examples of preferred fatty acids are neoacids, such as neononanoic acid and neodecanoic acid, which are highly branched synthetic trialkylacetic acids and are also known as versatile acids.

[0074] In a preferred embodiment, the phosphoric acid ester and the fatty acid are used in a weight ratio of 1:10 to 10:1 and more preferably in a weight ratio of 1:5 to 5:1.

[0075] In a further preferred embodiment, phosphoric acid ester is used in combination with a water-immiscible organic solvent. Similarly, the methods according to the second, third and fourth aspects of the invention can be practiced in the presence of a water-immiscible organic solvent. Frequently, the presence of a water-immiscible organic solvent has been shown to further increase the recovery of iron ore mass and / or the iron recovery rate. Particularly useful water-immiscible organic solvents are aliphatic, aromatic and alkylaromatic hydrocarbons and mixtures thereof. Preferred solvents do not contain any polar groups in the molecule. Examples of suitable solvents are decane, Petition 870260052873, dated 01 / 06 / 2026, page 36 / 117 33 / 45 toluene, ethylbenzene, xylene, diethylbenzene, trimethylbenzene, naphthalene, tetralin, decalin and mixtures of commercial solvents, such as Shellsol®, Exxsol®, Isopar®, Solvesso® and / or kerosene types. In preferred embodiments, the water-immiscible solvent comprises a maximum of 50% by weight, preferably a maximum of 10% by weight, and especially preferably a maximum of 5% by weight, of aromatic components.

[0076] The water-immiscible organic solvent can be used as part of a concentrated additive comprising phosphoric acid ester and the water-immiscible organic solvent. In this embodiment, the presence of a water-immiscible organic solvent reduces the viscosity of the phosphoric acid ester and facilitates its handling and dispersion in the aqueous semi-fluid paste of the fine-grained mineral. Alternatively, the phosphoric acid ester and the water-immiscible organic solvent can be added separately to the aqueous semi-fluid paste of the fine-grained mineral before the magnetic separation process. Preferably, the phosphoric acid ester and the water-immiscible organic solvent are used in a weight ratio of 1:20 to 10:1 and, more preferably, in a weight ratio of 1:10 to 5:1. In a particularly preferred embodiment, the magnetic separation process is conducted in the absence of a water-immiscible organic solvent.

[0077] Optionally, a dispersant may additionally be added to the aqueous semi-fluid paste prior to magnetic separation to aid in the dispersion of the mineral assemblage and further enhance the efficiency of the magnetic separation process. Dispersants such as tannins, lignin sulfonates, and alkaline phosphates can provide a more stable semi-fluid paste with less sedimentation. Additional preferred dispersants are sodium silicate, sodium hexametaphosphate, sodium polyacrylate, and mixtures. Petition 870260052873, dated 01 / 06 / 2026, page 37 / 117 34 / 45 of these. A preferred additional dispersant is a mixture of caustic soda and sodium silicate. When a dispersant is added, its concentration is preferably from 1 to 5,000 ppm by weight, based on the mass of the raw iron ore. In a preferred embodiment, the beneficiation process is conducted in the absence of an additional dispersant.

[0078] The addition of a phosphate ester to the aqueous semi-fluid slurry of a fine-grained iron ore, according to the present invention, results in a high mass recovery of iron ore from an aqueous semi-fluid slurry of a fine-grained mineral comprising iron ore in a magnetic separation process. This is accompanied by high selectivity in silicate removal. Consequently, the presence of the phosphoric acid ester allows for the obtaining of additional quantities of valuable iron ore with a high iron content from previously unexploited minerals and, similarly, from landfill tailings. Simultaneously, the mass of tailings that must be disposed of is reduced. The various advantages of the present invention are applicable to a wide range of specific types of iron ore encountered in daily mining operations.

[0079] The observed iron recovery rates are also higher than those obtained with fatty acids used according to the state of the art. Furthermore, the use of a phosphate ester, according to the present invention, results in an improved separation of fine-grained concentrated iron ore from the aqueous semi-fluid slurry obtained by means of a magnetic separation process. Consequently, fewer solids remain in suspension in the aqueous phase and, therefore, the water can be easily treated for disposal or reused in the beneficiation process. Petition 870260052873, dated 01 / 06 / 2026, page 38 / 117 35 / 45 EXAMPLES

[0080] The additive compositions, according to Table 1, were tested on a laboratory scale in an SLon-100 Cycle High Gradient Pulsed Magnetic Separator. The iron ore samples used for this study were particularized in terms of chemical analysis and particle size analysis, with the results presented in Table 2 (hereinafter also referred to as raw iron ores).

[0081] The SiO2 content in the ores was determined by a gravimetric method. The ore was decomposed by an acid attack (HCl), leading to the dissolution of metallic oxides and hydroxides, leaving insoluble SiO2 as the residue.

[0082] The iron content of the ores was determined by a titration method in which the sample was decomposed by an acid attack (HCl), the trivalent iron was reduced to divalent iron by the addition of stannous chloride (SnCb) and mercuric chloride (HgCl) and the iron content was determined by titration with potassium dichromate (K2C2O7).

[0083] The particle size distribution was determined by laser diffraction according to ASTM B822-10, which is the method that should generally be applied to all particle size distributions referenced in this patent document. The results of these analyses are provided in Table 2 below. P80 represents the diameter of the sieve openings through which eighty percent of the particles will pass; D50 represents the average value of the particle size distribution (median diameter), i.e., the diameter of the particles that are 50% by weight of the sample mass smaller and 50% by weight of the sample mass larger; 38% pm represents the percentage of particles smaller than 38 pm; 20% pm represents the percentage of particles smaller than 20 pm; 10% pm represents the percentage of particles smaller than 10 pm. Petition 870260052873, dated 01 / 06 / 2026, page 39 / 117 36 / 45

[0084] Mineralogy was determined by X-ray diffraction, following Bragg's Law. X-ray diffraction analysis allows the identification of the mineral through the characterization of its crystalline structure. The results of this analysis are presented in Table 2 below.

[0085] The turbidity of the spills was determined by nephelometry with a Hach 2100Q Portable Turbidimeter (EPA), according to EPA method 180.1. The intensity of incident light scattered by the particles present in the sample was measured at right angles (90°) to the path of the incident light. The turbidimeter calibration allowed a measurement range of 0 to 1000 NTU (FNU).

[0086] All percentage values ​​refer to the percentage by weight, unless otherwise stated. Table 1: Phosphoric esters used Additive Chemical Characterization PAE 1 Mixture of 50% by weight of phosphoric acid monoester and 38% by weight of phosphoric acid diester with n-C12 / C14 alcohol ethoxylate (4 moles of ethylene oxide) PAE 2 Mixture of 48% by weight of phosphoric acid monoester and 49% by weight of phosphoric acid diesters with isotridecanol ethoxylate (10 moles of ethylene oxide) PAE 3 Mixture of phosphoric acid mono- and diesters with oleic alcohol ethoxylate (3 moles of ethylene oxide) PAE 4 Mixture of phosphoric acid mono- and diesters with 2-ethylhexanol in approximately equal proportions PAE 5 87.5% crude soybean fatty acid 12.5% ​​mixture of phosphoric acid mono- and diesters with ethoxylate of isotridecanol (8 moles of ethylene oxide) FA 1 (comp.) Sodium oleate FA 2 (comp.) Soybean fatty acid FA 3 (comp.) Sodium hexametaphosphate Petition 870260052873, dated 01 / 06 / 2026, page 40 / 117 37 / 45 Table 2. Characterization of raw iron ores used for beneficiation by magnetic separation. Iron ores A and B contain a higher proportion of sludge; iron ore C contains mainly fine tailings. Iron Ore A Iron Ore B Iron Ore C Fe Content 49.3% 41.4% 6.4% FeCuO4 Content 0.0% 0.0% 19.7% SiO2 Content 17.5% 36.8% 36.7% P80 34 pm 50 pm 240 pm D50 14 pm 18 pm 92 pm 38% pm 94.9% 68.1% 8.0% 20% pm 59.4% 54.2% 2.4% 10% pm 37.0% 31.2% 0.8% MINERALOGY Hematite 38.1% 55.7% nd Goethite 29.3% 2.0% nd Magnetite 1.5% 2.0% nd Quartz 14.4% 33.6% nd Kaolinite 16.5% 6.7% nd nd = not determined

[0087] For magnetic separation tests, the Separator The Slon-100 Cycle High Gradient Pulsed Magnetic Separator was set to a pulsation of 100 rpm and a magnetic field intensity of 10,000 G (1 T). Pulsation was initiated and the water flow in the magnetic separation feed was set to a flow rate of 14 L / minute.

[0088] The semi-fluid raw ore slurry was prepared as follows: 200 grams of the respective raw iron ore were suspended in running water to provide a semi-fluid slurry with 54% by weight solids content. As the pH of the slurry was in the range of 7.0 to 7.5, no further adjustment was necessary. An additive according to Tables 3 to 5 was added to the slurry. Dosage rates Petition 870260052873, dated 01 / 06 / 2026, page 41 / 117 The 38 / 45 figures presented in Tables 3 to 5 refer to the mass of additive per mass of dry raw iron ore. The semi-fluid paste was conditioned with the additive for 3 minutes and then loaded into the magnetic separator feed.

[0089] The non-magnetic mass (tailings) and the magnetic mass (concentrated iron ore) were collected in separate containers and dried in a laboratory oven. Both samples (magnetic and non-magnetic) were then analyzed for weight, S1O2 content, and iron content, according to the methods described above. The process flowchart is shown in Figure 1.

[0090] The results are provided in terms of the following parameters: Mass recovery (% by weight): percentage of concentrated (magnetic) iron ore relative to the total mass of raw iron ore. Mass recovery Y can be calculated using the formula. Y = £* 100 = — lOOl F c — r ' where: C = dry mass of concentrate from magnetic separation; F = dry mass of raw ore fed for magnetic separation; f = Fe content fed; c = concentrated Fe content; er = Fe content in tailings. Iron Recovery Rate (% by weight): percentage of Fe in the raw ore that is recovered by the concentration process (magnetic mass). Fe recovery can be calculated using the formula... Petition 870260052873, dated 01 / 06 / 2026, page 42 / 117 39 / 45 c R = Y * f S1O2 content (% by weight): S1O2 content present in the concentrated iron ore (magnetic mass). Iron content (% by weight): the amount of iron present in the concentrated iron ore (magnetic mass). Petition 870260052873, dated 01 / 06 / 2026, page 43 / 117 40 / 45 Table 3. Results of magnetic separation tests on iron ore A Example Phosphoric acid ester pH Mass recovery Fe recovery rate Fe content SiO2 content Δmass recovery ΔFe recovery rate 1 (comp.) none - 7.23 51.2% 59.9% 57.7% 11.7% — — 2 PAE 1 100 g / t 7.42 57.6% 66.7% 58.2% 10.3% +6.4% +6.8% 3 PAE 2 100 g / t 7.34 58.6% 67.7% 58.0% 10.9% +7.4% +7.8% 4 PAE 3 100 g / t 7.22 56.6% 65.0% 57.7% 12.3 % +5.4 % +5.1 % 5 PAE 4 100 g / t 7.12 56.8 % 64.1% 57.8 % 11.3% +5.6 % +4.2 % 6 PAE 5 100 g / t 7.24 57.5 % 67.4 % 58.3 % 11.1% +6.3 % +7.5 % 7 (comp.) FA1 100 g / t 7.36 52.9 % 62.4 % 58.2 % 10.3 % +1.7 % +2.5 % 8 (comp.) FA2 100 g / t 7.03 53.9 % 63.0 % 58.1 % 10.2% +2.7% +3.1% 9 (comp.) FA3 100 g / t 7.01 53.6 % 63.3 % 58.3 % 10.0 % +2.4 % +3.4 % 10 PAE 1 50 g / t 7.26 56.6 % 65.0 % 57.7 % 10.3 % +5.4 % +5.1 % 11 PAE 2 50 g / t 7.31 56.7 % 66.9 % 58.4 % 10.9 % +5.5 % +7.0 % 12 PAE 3 50 g / t 7.31 56.8 % 66.8 % 58.3 % 12.3 % +5.6 % +6.9 % 13 PAE 4 50 g / t 7.18 54.6 % 64.2 % 57.8 % 11.3 % +3.4 % +4.3 % 14 PAE 5 50 g / t 7.24 56.3 % 65.4 % 57.7 % 11.3% +5.1 % +5.5 % 15 (comp.) FA1 50 g / t 7.23 52.3 % 61.1 % 57.9 % 10.3 % +1.1 % +1.2 % 16 (comp.) FA2 50 g / t 7.00 53.6 % 62.6 % 57.7 % 10.2 % +2.4 % +2.7 % 17 (comp.) FA3 50 g / t 7.00 53.0% 63.1% 58.8% 10.1% +1.8% +3.2% Petition 870260052873, dated 01 / 06 / 2026, p. 44 / 117 41 / 45 Table 4. Results of magnetic separation tests on iron ore B Example Phosphoric acid ester pH Mass recovery Fe recovery rate Fe content SiO2 content Δmass recovery ΔFe recovery rate 1 (comp.) none - 7.88 52.1% 81.0% 64.3% 4.4% — — 2 PAE 1 150 g / t 7.86 55.7% 85.9% 63.8% 4.7% 3.6% 4.9% 3 PAE 2 150 g / t 7.88 56.9% 88.1% 64.1% 4.4% 4.8% 7.1% 4 PAE 3 150 g / t 7.86 55.5% 85.5% 63.7% 4.6% 3.4 % 4.5 % 5 PAE 4 150 g / t 7.88 55.5 % 86.0 % 64.1 % 4.9 % 3.4 % 5.0 % 6 PAE 5 150 g / t 7.87 57.4 % 88.4 % 63.7 % 4.6 % 5.3 % 7.4 % 7 (comp.) FA1 150 g / t 7.84 53.8 % 82.8 % 63.7 % 4.5 % 1.7 % 1.8 % 8 (comp.) FA2 150 g / t 7.86 54.9 % 84.0 % 63.4 % 4.9 % 2.8% 3.0% 9 (comp.) FA3 150 g / t 7.86 52.8 % 82.2 % 64.5 % 3.9 % 0.7 % 1.2 % 10 PAE 1 300 g / t 7.92 57.9 % 89.1 % 63.7 % 4.8 % 5.8 % 8.1 % 11 PAE 2 300 g / t 7.86 59.2 % 90.9 % 63.6 % 5.0 % 7.1 % 9.9 % 12 PAE 3 300 g / t 7.88 57.0 % 87.7 % 63.7 % 4.8 % 4.9 % 6.7 % 13 PAE 4 300 g / t 7.85 57.6 % 88.3 % 63.4 % 5.2 % 5.5 % 7.3 % 14 PAE 5 300 g / t 7.88 57.6 % 88.5 % 63.6 % 5.0 % 5.5 % 7.5 % 15 (comp.) FA1 300 g / t 7.86 54.5 % 83.5 % 63.4 % 5.2 % 2.4 % 2.5 % 16 (comp.) FA2 300 g / t 7.87 53.5 % 82.0 % 63.4 % 5.4 % 1.4 % 1.0 % 17 (comp.) FA3 300 g / t 7.85 53.8% 83.7% 64.4% 4.4% 1.7% 2.7% Petition 870260052873, dated 01 / 06 / 2026, p. 45 / 117 42 / 45 Table 5. Results of magnetic separation tests on C iron ore. Example Phosphoric acid ester pH Mass recovery FeCr2O4 recovery rate FeCr2O4 content SiO2 content Δmass recovery ΔC2O3 recovery rate 1 (comp.) none - 7.22 9.4% 36.4% 51.9% 14.9% — — 2 PAE 1 300 g / t 7.13 13.2% 50.9% 51.7% 14.0% 3.8% 14.5% 3 PAE 2 300 g / t 7.21 13.6% 52.4% 51.6% 14.2% 4.2% 16.0% 4 PAE 3 300 g / t 7.23 13.4% 51.7 % 51.6 % 14.4 % 4.0 % 15.3 % 5 (comp) FA1 300 g / t 7.23 11.3 % 43.7 % 51.7 % 14.3 % 1.9 % 7.3 % 6 (comp) FA2 300 g / t 7.18 10.8 % 41.7 % 51.7 % 14.6 % 1.4 % 5.3 % 7 (comp) FA3 300 g / t 7.16 10.2 % 39.7 % 52.3 % 13.9 % 0.8 % 3.3 % 8 PAE 1 500 g / t 7.2 13.8 % 53.0% 51.6 % 14.2 % 4.4 % 16.6 % 9 PAE 2,500 g / t 7.2 14.0 % 54.0 % 51.6 % 14.3 % 4.6 % 17.6 % 10 PAE 3,500 g / t 7.21 13.8 % 53.4 % 51.7 % 14.4 % 4.4 % 17.0 % 11 (comp) FA1 500 g / t 7.19 11.5 % 44.4 % 51.9 % 14.5 % 2.1 % 8.0 % 12 (comp) FA2 500 g / t 7.2 11.0 % 42.3% 51.7% 14.1 % 1.6 % 5.9 % 13 (comp) FA3 500 g / t 7.22 10.1 % 39.4 % 52.5 % 13.8 % 0.7 % 3.0 % Petition 870260052873, dated 01 / 06 / 2026, page 46 / 117 43 / 45

[0091] To evaluate potential side effects of beneficiating fine-grained iron ores in the presence of a phosphoric acid ester, the magnetic concentrates obtained from magnetic separation tests were subjected to a sedimentation process. Therefore, 1,000 mL of iron ore pulp (magnetic fraction) containing 10% by weight of solids and the residual additive were transferred to a graduated cylinder. 60 g / t of an anionic polyacrylamide ore was added as a flocculant. The pulp was mixed with the flocculant seven times. Immediately after the last movement, a stopwatch was started. After 1 hour, the turbidity of the overflow was measured. The results are presented in Tables 6 to 8. Table 6. Turbidity of the spill after 1 hour of sedimentation (iron ore A) Example Phosphoric acid ester Flocculant dosage Turbidity [NTU] ΔNTυ 1 (comp.) none - 60 g / t 194 - 2 PAE 1 100 g / t 60 g / t 97 -97 3 PAE 2 100 g / t 60 g / t 113 -81 4 PAE 3 100 g / t 60 g / t 109 -85 5 PAE 4 100 g / t 60 g / t 103 -91 6 PAE 5 100 g / t 60 g / t 101 -93 7 (comp.) FA1 100 g / t 60 g / t 409 +215 8 (comp.) FA2 100 g / t 60 g / t 196 +2 9 (comp.) FA3 100 g / t 60 g / t 493 +299 10 PAE 1 50 g / t 60 g / t 122 -72 11 PAE 2 50 g / t 60 g / t 130 -64 12 PAE 3 50 g / t 60 g / t 111 -83 13 PAE 4 50 g / t 60 g / t 128 -66 14 PAE 5 50 g / t 60 g / t 122 -72 Petition 870260052873, dated 01 / 06 / 2026, p. 47 / 117 44 / 45 Example Phosphoric acid ester Flocculant dosage Turbidity [NTU] ΔNTυ 15 (comp.) FA1 50 g / t 60 g / t 220 +26 16 (comp.) FA2 50 g / t 60 g / t 211 +17 17 (comp.) FA3 50 g / t 60 g / t 413 +219 Table 7. Overflow turbidity after 1 hour of sedimentation (iron ore B) Example Phosphoric acid ester Flocculant dosage Turbidity [NTU] ΔNTυ 1 (comp.) none - 15 g / t 232 — 2 PAE 1 150 g / t 15 g / t 121 -111 3 PAE 2 150 g / t 15 g / t 109 -123 4 PAE 3 150 g / t 15 g / t 113 -119 5 PAE 4 150 g / t 15 g / t 104 -128 6 PAE 5 150 g / t 15 g / t 136 -96 7 (comp.) FA1 150 g / t 15 g / t 234 +2 8 (comp.) FA2 150 g / t 15 g / t 236 +4 9 (comp.) FA3 150 g / t 15 g / t 835 +603 10 PAE 1,300 g / t 15 g / t 86 -146 11 PAE 2,300 g / t 15 g / t 85 -147 12 PAE 3,300 g / t 15 g / t 88 -144 13 PAE 4,300 g / t 15 g / t 84 -148 14 PAE 5 300 g / t 15 g / t 102 -130 15 (comp.) FA1 300 g / t 15 g / t 232 +0 16 (comp.) FA2 300 g / t 15 g / t 230 -2 17 (comp.) FA3 300 g / t 15 g / t 997 +765 Petition 870260052873, dated 01 / 06 / 2026, p. 48 / 117 45 / 45 Table 8. Overflow turbidity after 1 hour of sedimentation (iron ore C) Example Phosphoric acid ester Flocculant dosage Turbidity [NTU] ΔNTυ 1 (comp.) none - 5 202 — 2 PAE 1 300 g / t 5 25 -177 3 PAE 2 300 g / t 5 32 -170 4 PAE 3 300 g / t 5 27 -175 5 (comp) FA1 300 g / t 5 203 +1 6 (comp) FA2 300 g / t 5 202 0 7 (comp) FA3 300 g / t 5 685 +483 8 PAE 1 500 g / t 5 18 -184 9 PAE 2 500 g / t 5 15 -187 10 PAE 3 500 g / t 5 15 -187 11 (comp) FA1 500 g / t 5 205 +3 12 (comp) FA2 500 g / t 5 202 0 13 (comp) FA3 500 g / t 5 895 +693

[0092] Experimental results show that the iron recovery rate from an aqueous semi-fluid slurry of fine-grained iron ore in a magnetic separation process is improved in the presence of phosphoric acid esters. An additionally valuable iron ore with a high iron content is obtained, and the tailings mass is reduced. Furthermore, compared with fatty acids used according to the prior art, the separation of concentrated fine-grained iron ore is improved, as shown by the significantly reduced turbidity of the overflow obtained in the magnetic separation process. Consequently, fewer solids remain in suspension in the aqueous phase, and therefore the water can be reused in the process.

Claims

1. A method for beneficiating an iron ore from a fine-grained raw iron ore, comprising iron ore and a gangue mineral, characterized in that: (i) the fine-grained raw iron ore is dispersed in an aqueous phase to provide an aqueous semi-fluid slurry; (ii) the aqueous semi-fluid slurry is mixed with at least one phosphoric acid ester; (iii) the treated aqueous semi-fluid slurry is subjected to magnetic separation means to obtain a fraction of the fine-grained iron ore semi-fluid slurry that is enriched in iron ore and depleted of gangue mineral;and (iv) a concentrated iron ore is extracted from the iron ore semi-fluid pulp fraction that is enriched in iron ore, and wherein the phosphoric acid ester is a phosphoric acid monoester according to Formula (I), a phosphoric acid diester according to Formula (II) or a mixture of phosphoric acid monoester (I) and phosphoric acid diester (II). R1 ​​OA-. m P—OO Xn+ n / 2 (I) (II) wherein: R1 and R2 are identical or different and, Petition 870260052873, dated 01 / 06 / 2026, p. 50 / 117 2 / 5 independently of each other, are selected from the group consisting of alkyl groups, alkenyl groups, acyl groups, and optionally substituted phenyl groups, having from 6 to 40 carbon atoms; A is an alkylene group containing 2 to 6 carbon atoms; X is hydrogen or a cation with valence n; n is 1, 2, or 3; em is 0 or an integer from 1 to 20.

2. Method according to claim 1, characterized in that: R1 and / or R2 is an alkyl or alkenyl group, having from 6 to 40 carbon atoms, where is 0.

3. Method according to claim 2, characterized in that: R1 and / or R2 is an alkyl or alkenyl group having from 6 to 40 carbon atoms, where is an integer from 1 to 20.

4. Method according to claim 2, characterized in that R1 and / or R2 is an acyl group of the General Formulas R5-C(O)-, and R6-C(O)-, in which R5 and R6 are identical or different and, independently of each other, are selected from alkyl and alkenyl groups having from 5 to 39 carbon atoms, where is an integer from 1 to 20.

5. Method according to claim 2, characterized in that: Petition 870260052873, dated 01 / 06 / 2026, p. 51 / 117 3 / 5 R1 and / or R2 is an optionally substituted aryl group having from 6 to 40 carbon atoms, where is an integer from 1 to 20.

6. Method according to claim 5, characterized in that R1 and / or R2 is a phenyl group substituted with an alkyl group, having from 1 to 36 carbon atoms.

7. Method according to claim 5, characterized in that R1 and / or R2 is a tristyrylphenyl group.

8. Method, according to any one of claims 1 to 6, characterized in that R1 and / or R2 have from 6 to 24 carbon atoms.

9. Method, according to any one of claims 1 to 8, characterized in that: X is hydrogen, and en is 1.

10. A method according to any one of claims 1 to 9, characterized in that phosphoric acid ester is added to the aqueous semi-fluid slurry of fine-grained raw iron ore at a concentration of 1 ppm by weight to 5,000 ppm by weight relative to the mass of the raw ore.

11. A method according to any one of claims 1 to 10, characterized in that the phosphoric acid ester is used in combination with a fatty acid.

12. A method according to any one of claims 1 to 11, characterized in that the phosphoric acid ester is used in combination with a water-immiscible organic solvent.

13. Method, according to any one of claims 1 to 12, characterized in that the fine-grained raw iron ore comprising an iron ore and a gangue mineral has an average particle size value of less than 500 μm, or less than 200 μm, as determined in accordance with ASTM B822-10.

14. A method according to any one of claims 1 to 13, characterized in that the fine-grained raw iron ore comprising an iron ore and a gangue mineral has an average particle size distribution value (D50; median diameter) of less than 100 μm and yet less than 20 μm, as determined in accordance with ASTM B822-10.

15. A method, according to any one of claims 1 to 14, characterized in that the fine-grained raw iron ore comprises a ferrimagnetic or paramagnetic iron ore that is attracted by a magnet.

16. Method, according to any one of claims 1 to 15, characterized in that the fine-grained raw iron ore comprises an oxide iron ore.

17. Method, according to any one of claims 1 to 16, characterized in that the fine-grained raw iron is a low-grade iron ore having an iron content of 10 to 53% by weight.

18. Method, according to any one of claims 15 to 17, characterized in that the iron ore comprises iron in the form of an oxide and / or oxyhydroxide selected from the group consisting of magnetite, hematite, goethite, limonite or any mixture thereof.

19. Method, according to any one of claims 15 to 18, characterized in that the iron ore comprises iron in the form of an oxide mixed metal iron ore. Petition 870260052873, dated 01 / 06 / 2026, page 53 / 117 5 / 5 20. Method according to claim 19, characterized in that the oxide-mixed metal iron ore comprises, in addition to iron and oxygen, at least one additional metal selected from the 4th period of the periodic table of elements.

21. Method according to claim 19 or 20, characterized in that the oxide mixed metal iron ore comprises, in addition to iron and oxygen: at least one additional metal selected from the group consisting of titanium, vanadium, chromium, manganese and / or zinc, or titanium or vanadium.

22. A method according to any one of claims 19 to 21, characterized in that the oxide mixed metal iron ore is selected from the group consisting of chromite, ilmenite, franklinite, and mixtures thereof.

23. Use of a phosphoric acid ester, as defined in any one of claims 1 to 22, characterized in that it is in a method for beneficiating an iron ore from a fine-grained raw iron ore, comprising an iron ore and a gangue mineral.

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