Method for treatment of phosphate ores and use of monophosphorous ester a

Description

1 / 30 “METHOD FOR TREATING PHOSPHATE ORES AND USE OF MONOPHOSPHORIUM ESTER A” Technical Field of the Invention

[001] The present invention relates to a method for treating phosphate ores containing heavy metals by reverse flotation, in which a monophosphoric ester is used as a collector for the flotation of carbonates. The method, according to the invention, allows reducing the heavy metal content in phosphate ores. Background of the Invention

[002] Global phosphate consumption, primarily for the production of phosphoric acid and fertilizers (95%), exceeded 47 million tons in 2019 and is expected to reach more than 50 million tons in 2023 (USGS). Phosphates are produced by mining phosphate rocks collected from marine sediment deposits (75%), igneous and metamorphic deposits (15 to 20%), or biogenetic deposits (2 to 3%). The main source of phosphates comes from calcium phosphate apatite (Cas(PO4)3) (F, Cl, OH) ores, whose global reserves are mainly located in North Africa (Morocco), the United States (Florida), Russia, and China. These ores represent approximately 80% of the total global production of phosphate rocks and generally contain between 18% and 35% P2O5.The predominant types of apatite in these ores are Francolite or Colophane, which, in addition to calcium phosphate, contain varying amounts of carbonates (such as calcite, dolomite, or magnesite), silicates, clays (illite, kaolinite, smectite, etc.), or even organic residues.

[003] Phosphate ore processing techniques depend primarily on the type of associated gangue present in the extracted rock. The historical beneficiation method used for half a century has been froth flotation. Sedimentary phosphate ore may contain carbonate gangue or Petition 870260070396, dated 07 / 15 / 2026, page 10 / 39 2 / 30 siliceous and / or silicocarbonate gangue. Silica and phosphates have significantly different physicochemical properties and can be easily separated by flotation. On the other hand, carbonates and phosphates have similar physicochemical properties and behave similarly during flotation operations; both are found as floated or compacted products.

[004] Typically, the ore is first crushed and suspended in water. Then, the collector is added, often in combination with other additives such as frothers, pH regulators, dispersants, depressants and / or stimulants (activators), to separate the valuable minerals from the gangue minerals of the ore. After a conditioning period, the flotation process begins, which involves blowing air into the suspension to break up the fine ore particles and produce foam on the surface. Three types of phosphate flotation methods have been developed in the industry to improve ores: direct flotation, reverse flotation and the Crago method. In a direct flotation method, the collector makes the surface of the minerals more hydrophobic, while the hydrophilic gangue minerals do not adhere to the gas bubbles and remain in solution. The foam from the mineral collector is then removed and treated.In a reverse flotation method, the valuable minerals in the ore remain in solution and the gangue is carried in the froth, which is then removed. The Crago method, on the other hand, uses coarse flotation with fatty acids, followed by deoiling flotation and cleaning with amines.

[005] The objective of these flotation methods is to enrich the mixture with valuable minerals with the best possible yield. To meet the growing demand for phosphate rocks and the progressive depletion of global reserves of high-grade phosphate, industries are therefore encouraged to improve enrichment technologies to valorize phosphate ores with lower P2O5 content. Petition 870260070396, dated 07 / 15 / 2026, page 11 / 39 3 / 30

[006] Removing carbonates from phosphate ore has proven particularly difficult, and several nonionic, anionic and cationic surfactants have been proposed as collectors.

[007] Fatty acid-based scavenger systems are generally used to increase the hydrophobicity differences between the material to be retained and the material to be removed. The main primary scavengers are based on partially unsaturated fatty acids (C12-C18), used at pH 4-5, with phosphoric acid as a depressant. Because fatty acids are poorly soluble in water at this pH, secondary scavengers, usually anionic or non-ionic surfactants, are used to improve selectivity and recovery.

[008] Application WO 2018 / 197476 describes a mixture of unsaturated fatty acids, pegylated alcohol and a sulfide-based surfactant, used at a dose of 500 g / tf in a pH range of 4.9 to 5.2.

[009] A mixture of a fatty acid and an aromatic sulfonic acid used at a dose of 806 g / tf in a pH range of 5.0 to 5.2 is described in application WO 2010 / 162344.

[0010] US patent 8,657,118 B2 describes a reverse flotation method using mixtures of phosphoric monoester and phosphoric diester in grades of 340 g / t and 500 g / ton in order to enrich ores in P2O5.

[0011] State-of-the-art reverse flotation methods have many disadvantages.

[0012] They may involve the use of foaming agents, pH regulators or activating agents. In particular, these methods require large quantities of collectors and involve operation in an acidic pH range.

[0013] In addition, the ores to be processed may contain elements that can pollute the soil or groundwater, such as cadmium (Cd), Petition 870260070396, dated 07 / 15 / 2026, p. 12 / 39 4 / 30 copper (Cu), arsenic (As), lead (Pb), nickel (Ni) or even chromium (Cr).

[0014] Cadmium levels in fertilizers are under special scrutiny by the European Parliament and other institutions, which are demanding limits for cadmium in phosphate fertilizers. Hence the importance of reducing the concentration of Cd, as well as other heavy metals such as arsenic.

[0015] In general, the reverse flotation of siliceous and calcareous sedimentary phosphates remains a constant industrial challenge. Therefore, finding a suitable collector and / or formulation that combines efficient silicon carbonate removal, good flotation yields, and manageable foam properties remains a high priority in this field.

[0016] Calcite increases the consumption of sulfuric acid in the manufacture of phosphoric acid and fertilizers, and significant levels of toxic impurities have been identified in dolomite ores. Therefore, despite the various advances made in recent years to solve these problems, improvements in the flotation process of phosphate rocks are still needed.

[0017] There is therefore a need for new, simpler and less expensive methods for treating phosphate ores, allowing for the enrichment of their P2O5 content, but also for the reduction of their heavy metal content, such as cadmium and arsenic. Brief Description of the Invention

[0018] The present invention relates to a method for treating phosphate ores containing heavy metals by reverse flotation, the method comprising the following steps: - (i) add, to an aqueous suspension of phosphate ore, a monophosphoric ester A of formula (I): Ri - O - P(=O) - (OH)2 (I) where R1 is a saturated or unsaturated, linear or branched hydrocarbon chain comprising 6 to 10 carbon atoms, Petition 870260070396, dated 07 / 15 / 2026, p. 13 / 39 5 / 30 preferably an alkyl group, alone or mixed with a compound B chosen from the group consisting of: a monophosphoric ester of formula (II) R2 - O - P(=O) - (OH)2 (II) wherein R2 is a saturated or unsaturated, linear or branched hydrocarbon chain comprising from 6 to 18 carbon atoms, preferably an alkyl group, different from the R1 group of the monophosphoric ester A of formula (I), an alcohol, a fatty acid, a fixed oil, a sulfate, a sulfonate, an ether and mixtures thereof; - (ii) inject gas into the aqueous suspension to form foam; and - (iii) remove foam and recover the aqueous suspension from the treated ore.

[0019] The present invention also relates to the use of such monophosphoric ester A, alone or in combination with compound B, as described herein, for the treatment of phosphate ores containing heavy metals.

[0020] Other aspects of the invention are described below and in the claims. Figures

[0021] [Figure 1]: Example of a laboratory-scale flotation column. Detailed Description of the Invention

[0022] The inventors have developed a method that meets the expressed needs. The proposed method does not present the disadvantages of the prior art. It allows increasing the P2O5 content of the ore using a smaller amount of collector. It also allows reducing the heavy metal content of the ore, particularly cadmium and arsenic. Petition 870260070396, dated 07 / 15 / 2026, page 14 / 39 6 / 30

[0023] The various embodiments presented throughout the description can be used alone or in combination with each other, without limitation on the number of combinations.

[0024] Thus, the invention relates to a method for treating phosphate ores containing heavy metals by reverse flotation, the method comprising the following steps: - (i) add, to an aqueous suspension of phosphate ore, a monophosphoric ester A of formula (I): Ri - O - P(=O) - (OH)2 (I) wherein R1 is a saturated or unsaturated, linear or branched hydrocarbon chain comprising 6 to 10 carbon atoms, preferably an alkyl group, alone or mixed with a compound B chosen from the group consisting of: a monophosphoric ester of formula (II) R2 - O - P(=O) - (OH)2 (II) wherein R2 is a saturated or unsaturated, linear or branched hydrocarbon chain comprising from 6 to 18 carbon atoms, preferably an alkyl group, different from the R1 group of the monophosphoric ester A of formula (I), an alcohol, a fatty acid, a fixed oil, a sulfate, a sulfonate, an ether and mixtures thereof; - (ii) inject gas into the aqueous suspension to form foam; and - (iii) remove foam and recover the aqueous suspension from the treated ore.

[0025] Advantageously, the treatment method according to the invention allows reducing the content of heavy metals present in phosphate ores, such as Cadmium, Arsenic, Lead, Nickel, Chromium, Copper and Zinc, in Petition 870260070396, dated 07 / 15 / 2026, p. 15 / 39 7 / 30 Cadmium and Arsenic specific.

[0026] In particular, the method according to the invention can allow the elimination of at least 60% by weight of the heavy metals present in the phosphate ore. Advantageously, at least 70% by weight of the heavy metals are eliminated, particularly advantageously at least 80% of the heavy metals are eliminated.

[0027] In particular, the method according to the invention allows for the removal of at least 60% by weight of the cadmium and arsenic present in the phosphate ore, advantageously, at least 70% by weight of the cadmium and arsenic are removed, particularly advantageously, at least 80% of the cadmium and arsenic are removed.

[0028] The advantages of the method according to the invention make it particularly applicable to the treatment of phosphate ores on an industrial scale. Stage (i)

[0029] Step (i) comprises adding to an aqueous suspension of phosphate ore a monophosphoric ester A of formula (I): Ri - O - P(=O) - (OH)2 (I) where R1 is a saturated or unsaturated, linear or branched hydrocarbon chain comprising 6 to 10 carbon atoms, preferably an alkyl group, alone or mixed with a compound B chosen from the group consisting of: a monophosphoric ester of formula (II): R2 - O - P(=O) - (OH)2 (II) where R2 is a hydrocarbon chain, saturated or unsaturated, linear or branched, comprising from 6 to 18 carbon atoms, preferably from 6 to 10 carbon atoms, preferably a group Petition 870260070396, dated 07 / 15 / 2026, p. 16 / 39 8 / 30 alkyl, other than the Ri group of the monophosphoric ester A of formula (I), an alcohol, a fatty acid, a fixed oil, a sulfate, a sulfonate, an ether and mixtures thereof. Aqueous suspension of phosphate ore

[0030] Phosphate ore, also called “phosphate rock”, refers to an exogenous rock containing phosphate. The phosphate ore useful in the present invention can be extracted from the Khouribga site (Bni-Amir), Morocco.

[0031] Typically, phosphate ore has a P2O5 content ranging from 18 to 35%, by weight, relative to the total weight of the phosphate ore.

[0032] The aqueous suspension is typically prepared by mixing phosphate ore with water. The phosphate ore is in the form of particles. Advantageously, the ore particles have a size ranging from 40 µm to 125 µm, or from 40 µm to 160 µm. The particle size is determined by sieving. Thus, before mixing with water, the phosphate ore is typically pre-ground and separated into sizes.

[0033] The mass percentage of phosphate ore in the aqueous suspension, also called slurry, typically ranges from 10% to 30%, preferably from 10% to 20%, with the percentage expressed as % by weight relative to the total weight of the phosphate ore suspension.

[0034] The monophosphoric ester A of formula (I), alone or in mixture with compound B, acts as a “collector” for the flotation of carbonates.

[0035] The “collector” has the ability to adsorb carbonate particles present in the phosphate ore onto its surface, thus allowing their separation and elimination during subsequent steps of the method.

[0036] The “collector” will also form a complex with the heavy metals present in the ore, and this complex will then be eliminated, at least in part, during the subsequent steps of the method. Petition 870260070396, dated 07 / 15 / 2026, page 17 / 39 9 / 30 Monophosphoric ester A

[0037] The nature of the hydrocarbon chain, preferably the alkyl group, in particular the length of the hydrocarbon chain, preferably the alkyl chain, and the presence of branching, can influence the ability of the monophosphoric ester to interact with carbonates and heavy metals present in phosphate ore.

[0038] The Ri group of the monophosphoric ester A of formula (I) is a saturated or unsaturated, linear or branched hydrocarbon chain comprising 6 to 10 carbon atoms, preferably an alkyl group.

[0039] Advantageously, the R1 group of the monophosphoric ester A of formula (I) is a linear alkyl group comprising from 6 to 10 carbon atoms, preferably from 7 to 10 carbon atoms, preferably from 8 to 9 carbon atoms, particularly preferably comprising 8 carbon atoms.

[0040] Advantageously, the Ri group of the monophosphoric ester A of formula (I) is a branched alkyl group comprising from 6 to 10 carbon atoms, preferably from 8 to 9 carbon atoms.

[0041] Preferred branched Ri groups include 2-ethylhexyl, 24-4 trimethylpentyl and 3-5-5 trimethylhexyl.

[0042] Advantageously, the Ri group of the monophosphoric ester A of formula (I) is a linear alkyl group comprising 8 or 9 carbon atoms or a branched alkyl group comprising 8 or 9 carbon atoms.

[0043] According to certain embodiments, the collector consists of the monophosphoric ester A of formula (I) as described above.

[0044] In an equivalent number of carbons, the presence of branching in the hydrocarbon chain, preferably of the alkyl group, of the Ri group of the monophosphoric ester A can then allow minimizing the amount Petition 870260070396, dated 07 / 15 / 2026, p. 18 / 39 10 / 30 of foam (also called float) that is removed during step (iv) of the method, while allowing the ore to be enriched in P2O5 and heavy metals to be removed. Combination of monophosphoric ester A and compound B

[0045] The combination of a monophosphoric ester A and compound B may also influence the amount of foam formed and the enrichment of the ore in P2O5.

[0046] When compound B is present, it is chosen from the group consisting of: a monophosphoric ester of formula (II): R2 - O - P(=O) - (OH)2 (II) where R2 is a hydrocarbon chain, saturated or unsaturated, linear or branched, with 6 to 18 carbon atoms, preferably with 6 to 10 carbon atoms, preferably an alkyl group, different from the R1 group of the monophosphoric ester A of formula (I) as described above, an alcohol, a fatty acid, a fixed oil, a sulfate, a sulfonate, an ether and mixtures thereof.

[0047] The combination of monophosphoric ester A and compound B can minimize the amount of foam (float) removed in step (iv) of the method, while enriching the ore in P2O5 and removing heavy metals, compared to using only monophosphoric ester A. In addition, the cost of the composition comprising monophosphoric ester A and compound B can also be reduced. Combination of monophosphoric ester A and monophosphoric ester of formula ÍUl

[0048] According to the embodiments, compound B is a monophosphoric ester of formula (II): Petition 870260070396, dated 07 / 15 / 2026, p. 19 / 39 11 / 30 R2 - O - P(=O) - (OH)2 (II) wherein the R2 group, other than Ri, is a saturated or unsaturated, linear or branched hydrocarbon chain comprising from 6 to 18 carbon atoms, preferably from 6 to 14 carbon atoms, particularly preferably from 6 to 10 carbon atoms, preferably an alkyl group.

[0049] In certain embodiments, the R1 group of the monophosphoric ester A of formula (I) is a linear alkyl group comprising from 6 to 10 carbon atoms and the R2 group of the monophosphoric ester B of formula (II), other than R1, is a saturated or unsaturated hydrocarbon chain, linear or branched, comprising from 6 to 10 carbon atoms, preferably a linear alkyl group comprising from 6 to 10 carbon atoms.

[0050] In certain embodiments, the R1 group of the monophosphoric ester A of formula (I) is a linear alkyl group comprising from 6 to 10 carbon atoms and the R2 group of the monophosphoric ester B of formula (II), other than R1, is a branched alkyl group comprising from 6 to 10 carbon atoms.

[0051] Preferably, the R1 group of the monophosphoric ester A of formula (I) is a linear alkyl group comprising from 7 to 10 carbon atoms, preferably from 8 to 9 carbon atoms, particularly preferably comprising 8 carbon atoms and the R2 group of the monophosphoric ester B of formula (II), other than R1, is a branched alkyl group comprising 8 or 9 carbon atoms.

[0052] A synergistic effect related to the combination of the two monophosphoric esters can be observed, particularly with regard to the enrichment of the ore in P2O5. Combination of monophosphoric ester A and alcohol

[0053] According to certain embodiments, compound B is Petition 870260070396, dated 07 / 15 / 2026, p. 20 / 39 12 / 30 an alcohol of formula R3-OH (III), wherein R3 is a saturated or unsaturated, linear or branched hydrocarbon chain comprising from 2 to 20 carbon atoms, preferably from 6 to 10 carbon atoms, particularly preferably from 8 to 10 carbon atoms, preferably an alkyl group.

[0054] Preferably, the Ri group of the monophosphoric ester A of formula (I) is a linear alkyl group comprising from 7 to 10 carbon atoms, preferably from 8 to 9 carbon atoms, particularly preferably comprising 8 carbon atoms and the R3 group of the alcohol of formula (III) is a linear alkyl group comprising from 6 to 10 carbon atoms, preferably from 8 to 10 carbon atoms.

[0055] Advantageously, the percentage by mass of alcohol is less than 70%, preferably less than 50%, preferably less than 40%, preferably less than 30% in relation to the mass of monophosphoric ester A and alcohol. Combination of monophosphoric ester A and sulfate or sulfonate

[0056] According to certain embodiments, compound B is a salt of a sulfonic acid with a hydrocarbon chain, or a salt of an aromatic sulfonic acid substituted with a hydrocarbon chain, the hydrocarbon chain being saturated or unsaturated, linear or branched, comprising from 2 to 20 carbon atoms, preferably an alkyl group. Preferably, compound B is a salt of an alkylated aromatic sulfonic acid, the alkyl group being linear and comprising from 10 to 14 carbon atoms, the sodium salt of dodecylbenzene sulfonic acid being particularly preferred.

[0057] Compound B may be a sulfate with a saturated or unsaturated, linear or branched hydrocarbon chain comprising from 2 to 20 carbon atoms, preferably an alkyl sulfate. Petition 870260070396, dated 07 / 15 / 2026, page 21 / 39 13 / 30

[0058] Preferably, the alkyl group is linear and comprises from 10 to 14 carbon atoms, sodium dodecyl sulfate being particularly preferred.

[0059] Preferably, the Ri group of the monophosphoric ester A of formula (I) is a linear alkyl group comprising from 7 to 10 carbon atoms, preferably from 8 to 9 carbon atoms, particularly preferably comprising from 8 carbon atoms and compound B is a salt of an alkylated aromatic sulfonic acid, the alkyl group being linear and comprising from 10 to 14 carbon atoms.

[0060] Preferably, the Ri group of the monophosphoric ester A of formula (I) is a linear alkyl group comprising from 7 to 10 carbon atoms, preferably from 8 to 9 carbon atoms, particularly preferably comprising from 8 carbon atoms and compound B is an alkyl sulfate, the alkyl group being linear and comprising from 10 to 14 carbon atoms.

[0061] Advantageously, the mass percentage of the alkylated sulfonic acid salt or the alkylated aromatic sulfonic acid salt is less than or equal to 40% relative to the mass of the monophosphoric ester A and the alkylated sulfonic acid salt or the alkylated aromatic sulfonic acid salt.

[0062] Advantageously, the mass percentage of alkyl sulfate is less than 70%, preferably less than 50%, preferably 40%, preferably 30%, preferably 20% relative to the mass of monophosphoric ester A and alkyl sulfate. Combination of monophosphoric ester A and ether

[0063] According to certain embodiments, compound B is an ether, pegylated or not, of formula R5-(OC2H4)nO-R6 (IV) with R5 being an alkyl or aromatic or alkylated aromatic group and R6 being an alkyl group or a hydrogen atom and n represents an integer ranging from 0 to Petition 870260070396, dated 07 / 15 / 2026, p. 22 / 39 14 / 30 10.

[0064] The term “alkylated aromatic” means an aromatic group substituted by a linear or branched alkyl group comprising from 2 to 20 carbon atoms.

[0065] Preferably, R5 is an alkylated aromatic group, R6 is a hydrogen atom and is different from zero.

[0066] Preferably, R5 is an aromatic group substituted by a branched alkyl group containing 6 to 10 carbon atoms, R6 is a hydrogen atom and is different from zero.

[0067] According to certain embodiments, compound B is an ether, pegylated or not, of formula R5-(OC2H4)nO-R6 (IV) with R5 being an unsaturated hydrocarbon chain or an aromatic group substituted by an unsaturated hydrocarbon chain and R6 being an unsaturated hydrocarbon chain or a hydrogen atom and represents an integer ranging from 0 to 10.

[0068] Preferably, the Ri group of the monophosphoric ester A of formula (I) is a linear alkyl group comprising from 7 to 10 carbon atoms, preferably from 8 to 9 carbon atoms, particularly preferably comprising 8 carbon atoms and compound B is a compound of formula (IV) with R5 being an alkylated aromatic group, preferably carrying from 6 to 10 carbon atoms, R6 being a hydrogen atom and being non-zero.

[0069] Advantageously, the mass percentage of ether is less than 40% relative to the mass of monophosphoric ester A and ether. Combination of monophosphoric ester A and fatty acid or fixed oil.

[0070] In certain embodiments, compound B is a fatty acid or a fixed oil.

[0071] Preferably, component B is a fatty acid. Petition 870260070396, dated 07 / 15 / 2026, p. 23 / 39 15 / 30 saturated or unsaturated with at least 12 carbon atoms. Preferably, the fatty acid comprises 12 to 22 carbon atoms, more preferably 14 to 20 carbon atoms, and even more preferably 16 to 18 carbon atoms.

[0072] Advantageously, the mass percentage of fatty acid is less than 60%, preferably less than 40%, preferably less than 20% in relation to the mass of monophosphoric ester A and fatty acid.

[0073] When compound B is a fixed oil, it can be rapeseed oil or sunflower oil.

[0074] Advantageously, the mass percentage of the fixed oil is less than 50%, preferably less than 30%, preferably less than 10% in relation to the mass of the monophosphoric ester A and the fixed oil.

[0075] According to the embodiments, the collector consists of the monophosphoric ester A of formula (I) and compound B as described above.

[0076] The combination of a monophosphoric ester A of formula (I) and a diphosphoric ester leads to a significant reduction in collector efficiency compared with a collector consisting only of the monophosphoric ester A of formula (I).

[0077] The collector according to the invention is more efficient than prior art collectors and can be used in smaller quantities.

[0078] Advantageously, the amount of monophosphoric ester A and compound B added during step (i) varies from 100 g to 500 g per tonne of phosphate ores, preferably from 100 g to 300 g, particularly preferably from 120 g / tonne to 260 g / tonne of phosphate ores.

[0079] Advantageously, the collectors according to the invention allow for the development of their own foam without the need to add Petition 870260070396, dated 07 / 15 / 2026, p. 24 / 39 16 / 30 an additional foaming agent, such as methyl isobutyl carbinol (MIBC) or pine oil.

[0080] Preferably, the method of the present invention does not require the use of an additional frother, pH regulator or activator during the flotation method.

[0081] The mineral and collector suspensions according to the invention have a neutral pH and do not require the addition of a pH regulator. For example, a pH regulator is used when fatty acid-based collectors are used.

[0082] Furthermore, there is no need to use flotation activators, which can also act as pH regulators, such as sodium hydroxide or sulfuric acid.

[0083] According to the embodiments, the treatment method according to the invention further comprises a step i') before step i) of adding a depressant, such as phosphoric acid, and / or a step i'') between step i) and step ii) of adding an amine compound for silicate flotation. Step (i') of adding a depressant

[0084] Depressant agents such as phosphoric acid and its derivatives, diphosphonic acid [DPA] and orthophosphoric acid [OPA] can be used. Step (i'') of adding an amine compound for silicate flotation

[0085] To remove silicates from the phosphate ore to be treated, an amine scavenger, such as FLOTINOR™ and FLOTIGAM™ products, can be added to the aqueous suspension from step i). Gas injection stage (ii)

[0086] The gas injection stage (ii) allows the foam, composed of carbonates and heavy metals, to float to the surface of the suspension. For this, gas is injected in such a way as to form gas bubbles. Petition 870260070396, dated 07 / 15 / 2026, page 25 / 39 17 / 30 homogeneous particles that, after adsorption by the foam, will transport it by flotation to the surface of the suspension.

[0087] Gas bubbles can be formed by any means known to a person skilled in the art, for example, by a porous base, sintered glass, or by one or more injector nozzles.

[0088] The gas injected in step (ii) may be air, nitrogen or any other gas inert to the species present.

[0089] Gas injection in step (ii) can be carried out at a constant flow rate. A person skilled in the art will know how to adapt the gas injection flow rate.

[0090] Step (ii) is carried out with agitation to ensure a homogeneous distribution of gas bubbles in the aqueous suspension. Agitation may be ensured by any means known to those skilled in the art, such as mechanical agitation, such as a rotor, or magnetic agitation.

[0091] Generally, step (ii) can be performed for a time ranging from 5 seconds to 30 minutes, typically from 5 seconds to 5 minutes. Separation stage (iii)

[0092] The treatment method comprises a step (iii) of separating the foam containing carbonates and heavy metals from the ore suspension.

[0093] The recovered foam can eventually be reprocessed to separate and recover the extracted heavy metals.

[0094] The treated ore suspension obtained at the end of step (iii) is recovered after froth removal.

[0095] Typically, the foam is recovered in step (iii) from the top of the treated phosphoric acid solution by any means known to those skilled in the art. For example, flotation foam can be discharged into a recovery tank. Petition 870260070396, dated 07 / 15 / 2026, page 26 / 39 18 / 30

[0096] The efficiency of the method according to the invention is expressed in terms of: - percentage by mass of the floated (rejected) product expressed in relation to the total mass of the dry floated product and the recovered concentrate; - Mass percentages of magnesium oxide (MgO), tricalcium phosphate (BPL or bone calcium phosphate) or P2O5, expressed relative to the total mass of the dry concentrate, as well as the cadmium and arsenic content in the concentrate. The BPL content is obtained by multiplying the P2O5 content by a correction factor of 2.185.

[0097] Typically, the method according to the invention allows obtaining a mass percentage of floated (rejected) product expressed in relation to the total mass of recovered dry and concentrated floated product of less than 25%.

[0098] After treatment, the percentage of tricalcium phosphate (BPL or bone lime phosphate) or P2O5 expressed in relation to the total mass of the dry concentrate, as well as the cadmium and arsenic content in the concentrate are respectively increased and decreased compared to the untreated ore.

[0099] Advantageously, the percentage of tricalcium phosphate (BPL or calcium bone phosphate) is greater than or equal to 65% after implementing the method according to the invention. Advantageously, the percentage of P2O5 is greater than or equal to 30% after implementing the method according to the invention.

[00100] Advantageously, the percentage of tricalcium phosphate (BPL or calcium bone phosphate) is greater than or equal to 70% after implementing the method according to the invention. Advantageously, the percentage of P2O5 is greater than or equal to 32% after implementing the method according to the invention. Petition 870260070396, dated 07 / 15 / 2026, page 27 / 39 19 / 30

[00101] Figure 1 illustrates, in a non-limiting manner, devices capable of implementing the flotation treatment method according to the invention.

[00102] In certain embodiments, the method according to the invention is implemented in a flotation device, such as a flotation column combined with a foam recovery tank at the top of the column, as shown schematically in Figure 1.

[00103] Part I, referred to as the treatment part, comprises the flotation column, which consists of a glass column (1) filled with phosphate ore pulp conditioned with the flotation collector according to the invention. Gas is introduced at the bottom of the column and gas bubbles are formed by the passage of the gas through the sintered glass (2). The gas is generated by a gas generator (3) and its flow rate is controlled by a flow rate meter (4). The medium is agitated by a magnetic stir bar (5) with a magnetic stirrer (6), which allows for good distribution of the gas bubbles (7). Foam (8) is formed upon contact with the gas bubbles. The foam is then carried to the top of the column, in a foam discharge zone (9) corresponding to Part II, referred to as the separation part. The foam (8) then flows to a foam recovery tank (10).

[00104] The residence time in the flotation device is generally less than 30 minutes, preferably between 5 seconds and 5 minutes.

[00105] The ion flotation treatment method can be carried out at a temperature ranging from 15 to 90 °C or from 20 to 80 °C. Use of monophosphoric ester A, alone or in combination with compound B.

[00106] Another objective of the invention relates to the use of the ester Petition 870260070396, dated 07 / 15 / 2026, pp. 28 / 39 20 / 30 monophosphoric A, alone or in combination with compound B, as described above, for the treatment of phosphate ores containing heavy metals.

[00107] The use of monophosphoric ester A and compound The collector described above, according to the invention, allows for new, simpler, and less expensive methods of treating phosphate ores, enabling the enrichment of their P2O5 content but also reducing their content of heavy metals, such as cadmium and arsenic.

[00108] The collector according to the invention is more effective than prior art compositions and can be used in smaller quantities. Examples

[00109] The following non-restrictive examples illustrate exemplary embodiments of the invention.

[00110] Phosphate ore samples were collected at the Khouribga mine (Bni-Amir). They were crushed, mixed, homogenized, and quartered using a riffle sampler. They were then processed and analyzed. I. Mineralogical characterization of phosphate ore

[00111] The characterization and quantification of these samples were performed using different analytical techniques, including atomic absorption and ICP-MS. The results are presented in Table 1. P2O5 (%) CO2 (%) MgO (%) SiO2 (%) Cd (ppm) As (ppm) 28.57 8.66 0.3 6.42 27 13 Table 1: Characterization of a phosphate ore sample Khouribga

[00112] Phosphate ore is composed of heavy metals, Petition 870260070396, dated 07 / 15 / 2026, pp. 29 / 39 21 / 30 particularly cadmium (27 ppm) and arsenic (13 ppm). 2. SYNTHESIS OF MONOPHOSPHORIC ESTERS

[00113] All organic solvents were purchased and used as is, without purification. Chemicals were purchased from Aldrich and Merck and used without any purification. NMR spectra were recorded in deuterated solvent on a Bruker AC 400 spectrometer at 400 MHz for 1H NMR and at 50 MHz or 101 MHz for 13C NMR; δ is expressed in ppm relative to TMS (0 ppm) as internal standard for 1H and 13C, H3PO4 for phosphorus NMR. Splitting standards are designated as follows: s (singlet), d (doublet), t (triplet), m (multiplet), br (wide). Coupling constants (J values) are given in Hertz (Hz).

[00114] Alcohol (1 eq) is added dropwise to phosphorus(V) oxychloride (1.5 eq) with vigorous stirring at 0 °C for one hour under an inert atmosphere. The reaction mixture is stirred continuously for a period of about 4 to 5 h at room temperature. The resulting monoalkylphosphoryl dichloride is poured dropwise into ice-cold water and stirring is maintained for several hours (4 to 16 h). Then, the mixture is extracted with diethyl ether, and the combined organic phases are dried with magnesium sulfate (MgSO4) and concentrated under reduced pressure to obtain the appropriate product.

[00115] NMR analyses of the reaction product do not detect the presence of the phosphoric acid diester.

[00116] The reaction scheme for the synthesis of the monophosphoric ester is illustrated in Scheme 1. the 1)0 °C, 5h II r'zZ^*OH+POCI3* ο'ζ”^η'Ά'ΟΗκ υπ2) H2O, overnightR° OH (leq) (1.5eq) Petition 870260070396, dated 07 / 15 / 2026, pages 30 / 39 22 / 30 Scheme 1: General procedure for the preparation of monophosphoric esters 3. METHOD FOR ORE PROCESSING 3.1 Operating mode

[00117] A Denver D-12 flotation cell is used.

[00118] 200 g of dry, ground sedimentary phosphate ore with a size between 40 µm and 160 µm are suspended in 1.5 L of water. The pulp is conditioned with 500 g per ton (g / t) of phosphoric acid (H3PO4) as a depressant for 3 min at 1200 rpm, then the carbonate flotation collector is added at 250 g / t. After 2 min of conditioning, the amine collector “FLOTINOR” for silicate flotation is added at 200 g / t, followed by 30 seconds of conditioning. The flotation process is initiated immediately after air injection. The frothing product (floated product) and the concentrate are filtered, dried, weighed, and analyzed.

[00119] Unless otherwise indicated, the treatment method is as described above. 3.2 Evaluation of the different collectors

[00120] The methods preceded by “C” correspond to comparative examples.

[00121] Unless otherwise indicated, the percentages given below are mass percentages. Example 1: Evaluation of monophosphoric esters

[00122] Table 2 below shows the results obtained for each collector in terms of: - percentage by mass of the floated (rejected) product expressed in relation to the total mass of the dry floated product and the recovered concentrate; - mass percentages of magnesium oxide (MgO), tricalcium phosphate (BPL or bone calcium phosphate) or P2O5, expressed relative to Petition 870260070396, dated 07 / 15 / 2026, pp. 31 / 39 23 / 30 total mass of dry concentrate, as well as the cadmium and arsenic content in the concentrate. The GLP content is obtained by multiplying the P2O5 content by a correction factor of 2.185. Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (ppm) As (ppm) Reference Chain Alkyl content (g / t) Floated (Rejected) Content (%) in concentrate 1 C6 250 7.43 0.29 64.92 29.70 — — 3 Cs 250 24.74 0.30 71.24 32.59 8 4 4 C9 125 17.27 0.28 69.56 31.83 — — 5 Cio 250 6.68 0.29 66.59 30.47 — — C-6 C12 250 0.00 0.30 62.43 28.57 27 13 C-7 Cl4 250 0.00 0.30 62.43 28.57 27 13 C-8 ClS(Oleil) 250 0.00 0.30 62.43 28.57 27 13 Table 2

[00123] The mono-octylphosphoric ester collector at a concentration of 250 g / t allows obtaining a GPL content of 71.24 (32.59% P2O5) with a weight loss of 24.74%. The mono-nonylphosphoric ester collector allows obtaining a GPL content of 69.56 (31.83% P2O5) with a weight loss of 17.27% for a concentration of only 125 g / t.

[00124] Long-chain alkyl collectors have no effect on flotation (a method not part of the invention).

[00125] After treatment, the cadmium content is reduced by 75% and the arsenic content is reduced by 70%. Example 2: Evaluation of the combination of monophosphoric esters

[00126] As illustrated in Tables 3 to 6 below, the combination of two monophosphoric esters allows optimizing the amount of flotation rejected, obtaining a concentrate enriched with P2O5.

[00127] Tables 3 to 6 illustrate the effect of combining the ester with a linear C8 chain and an ester with a branched chain. Petition 870260070396, dated 07 / 15 / 2026, pp. 32-39 24 / 30 Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (ppm) As (ppm) Reference Composition Floated (Rejected) Grade (%) in concentrate 1 Octyl phosphate (100%) ___ 24.74 0.30 71.24 32.59 8 4 2 Octyl phosphate (80%) 2-ethylhexyl phosphate (20%) 18.20 0.36 70.12 32.08 7 4 3 Octyl phosphate (60%) 2-ethylhexyl phosphate (40%) 16.78 0.33 68.02 31.12 ___ ___ 4 Octyl phosphate (50%) 2-ethylhexyl phosphate (50%) 14.56 0.33 67.68 30.97 ___ ___ 5 Octyl phosphate (40%) 2-Ethylhexyl phosphate (60%) 14.78 0.34 69.36 31.74 ___ ___ 6 Octyl phosphate (20%) 2-Ethylhexyl phosphate (80%) 14.38 0.36 69.05 31.59 ___ ___ 7 ___ 2-Ethylhexyl phosphate (100%) 11.93 0.34 68.97 31.56 ___ ___ Table 3 Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (PPm) As (PPm) Reference Composition Floated (Rejected) Grade (%) in concentrate 1 Octyl phosphate (100%) ___ 24.74 0.30 71.24 32.59 8 4 2 Octyl phosphate (80%) 2,4,4-trimethylpentyl phosphate (20%) 16.30 0.34 70.22 32.13 7 4 3 Octyl phosphate (60%) 2,4,4-trimethylpentyl phosphate (40%) 14.66 ___ 70.36 32.19 7 4 4 Octyl phosphate (50%) 2,4,4-trimethylpentyl phosphate (50%) 12.93 0.46 69.03 31.58 ___ ___ 5 Octyl phosphate (40%) 2,4,4-trimethylpentyl phosphate (60%) 11.66 0.31 67.18 30.74 ___ ___ 6 Octyl phosphate (20%) 2,4,4-trimethylpentyl phosphate (80%) 11.33 0.31 69.08 31.61 ___ ___ 7 ___ 2,4,4-trimethylpentyl phosphate (100%) 9.67 0.31 66.55 30.45 ___ ___ Table 4 Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (PPm) As (PPm) Reference Composition Floated (Rejected) Grade (%) in concentrate 1 Octyl phosphate (100%) — 24.74 0.30 71.24 32.59 8 4 Petition 870260070396, dated 07 / 15 / 2026, pp. 33 / 39 25 / 30 Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (ppm) As (ppm) 2 Octyl phosphate (80%) 3,5,5-trimethylhexyl phosphate (20%) 21.32 0.32 70.35 32.19 7 4 3 Octyl phosphate (60%) 3,5,5-trimethylhexyl phosphate (40%) 19.99 0.32 69.07 31.60 ___ ___ 4 Octyl phosphate (50%) 3,5,5-trimethylhexyl phosphate (50%) 20.81 0.32 70.02 32.04 8 4 5 Octyl phosphate (40%) 3,5,5-trimethylhexyl phosphate (60%) 23.89 0.31 70.29 32.16 8 4 6 Octyl phosphate (20%) 3,5,5-trimethylhexyl phosphate (80%) 23.48 0.41 70.05 32.05 8 4 7 ___ 3,5,5-trimethylhexyl phosphate (100%) 21.10 0.32 68.59 31.38 ___ ___ Table 5 Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (PPm) As (PPm) Reference Composition Floated (Rejected) Grade (%) in concentrate 1 Decyl Phosphate (100%) — 6.68 0.29 66.59 30.47 — — 2 Decyl Phosphate (90%) Hexyl Phosphate (10%) 8.88 0.32 66.86 30.59 — — 3 Decyl Phosphate (80%) Hexyl Phosphate (20%) 8.88 0.31 67.25 30.77 — — 4 Decyl Phosphate (70%) Hexyl Phosphate (30%) 8.39 0.30 67.60 30.93 — — 5 Decyl phosphate (60%) Hexyl phosphate (40%) 16.46 0.28 68.41 31.30 — — 6 Decyl phosphate (50%) Hexyl phosphate (50%) 12.50 0.29 67.88 31.06 — — 7 Decyl phosphate (40%) Decyl phosphate hexyl (60%) 12.87 0.30 68.10 31.16 — — 8 Decyl phosphate (30%) Hexyl phosphate (70%) — — — — — — 9 Decyl phosphate (20%) Hexyl phosphate (80%) 8.91 0.29 67.89 31.06 — — 10 Decyl phosphate (10%) Hexyl phosphate (90%) 7.12 0.28 65.43 29.94 — — 11 — Hexyl phosphate (100%) 7.43 0.29 64.92 29.70 — — Table 6 Example 3: Evaluation of the combination of a monophosphoric ester and an alcohol.

[00128] Table 7 illustrates the effect of combining a monophosphoric ester and an alcohol. Petition 870260070396, dated 07 / 15 / 2026, pp. 34 / 39 26 / 30 Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (ppm) As (ppm) Reference Composition Floated (Rejected) Content (%) in concentrate 1 Octyl phosphate (100%) — 23.29 0.33 71.32 32.64 8 4 2 Octyl phosphate (90%) 1-Octanol (10%) 19.56 0.34 70.61 32.31 8 4 3 Octyl phosphate (80%) 1-Octanol (20%) 15.59 0.34 69.85 31.96 — — 4 Octyl phosphate (70%) 1-Octanol (30%) 15.04 0.34 69.82 31.94 — — 5 Octyl phosphate (60%) 1-Octanol (40%) 11.20 0.36 68.25 31.23 — — 6 Octyl phosphate (50%) 1-Octanol (50%) 10.20 0.35 64.49 29.51 — — 7 Octyl phosphate (40%) 1-Octanol (60%) 5.73 0.33 65.25 29.86 — — 8 Octyl phosphate (30%) 1-Octanol (70%) 4.69 0.35 64.45 29.49 — — 9 Octyl phosphate (20%) 1-Octanol (80%) 1.39 0.37 63.28 28.95 — — 10 Octyl phosphate (10%) 1-Octanol (90%) 4.19 0.36 64.13 29.34 — — 11 — 1-Octanol (100%) 0.84 0.36 62.95 28.80 — — Table 7

[00129] For compositions with less than 30% octanol by mass, a P2O5 content greater than or equal to 32% is obtained for the treated ore. Example 4: Evaluation of the combination of a monophosphoric ester and a sulfate.

[00130] Table 8 illustrates the effect of combining a monophosphoric ester and a sulfate. Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (PPm) As (PPm) Reference Composition Floated (Rejected) Grade (%) in concentrate 1 Octyl phosphate (100%) — 23.29 0.33 71.32 32.64 8 4 2 Octyl phosphate (90%) Sodium dodecyl sulfate (10%) 17.88 0.30 70.59 32.30 8 4 3 Octyl phosphate (80%) Sodium dodecyl sulfate (20%) 16.63 0.31 70.39 32.21 9 4 4 Octyl phosphate (70%) Sodium dodecyl sulfate (30%) 11.20 0.28 69.29 31.70 — — 5 Octyl phosphate (60%) Sodium dodecyl sulfate (40%) 8.91 0.3 67.84 31.04 — — 6 Octyl phosphate (50%) Sodium dodecyl sulfate (50%) 5.29 0.29 67.02 30.66 — — 7 Octyl phosphate (40%) Sodium dodecyl sulfate (60%) 3.59 0.28 65.3 29.88 — — Petition 870260070396, dated 07 / 15 / 2026, pp. 35 / 39 27 / 30 Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (ppm) As (ppm) C-8 Octyl phosphate (30%) Sodium dodecyl sulfate (70%) 0.00 0.30 62.43 28.57 27 13 C-9 Octyl phosphate (20%) Sodium dodecyl sulfate (80%) 0.00 0.30 62.43 28.57 27 13 C-10 Octyl phosphate (10%) Sodium dodecyl sulfate (90%) 0.00 0.30 62.43 28.57 27 13 C-11 Sodium dodecyl sulfate (100%) 0.00 0.30 62.43 28.57 27 13 Table 8

[00131] For compositions with less than 20% sulfate by mass, a BPL content greater than or equal to 32% is obtained for the treated ore. Example 5: Evaluation of the combination of a monophosphoric ester and a fatty acid.

[00132] Table 9 illustrates the effect of combining a monophosphoric ester and a fatty acid. Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (PPm) As (PPm) Reference Composition Floated (Rejected) Content (%) in concentrate 1 Octyl phosphate (100%) — 23.29 0.33 71.32 32.64 8 4 2 Octyl phosphate (80%) Linoleic acid (20%) 12.13 0.29 66.55 30.45 — — 3 Octyl phosphate (60%) Linoleic acid (40%) 8.93 0.30 64.79 29.64 — — 4 Octyl phosphate (50%) Linoleic acid (50%) 5.97 0.30 64.77 29.63 — — 5 Phosphate Octyl Phosphate (40%) Linoleic Acid (60%) 4.64 0.31 64.03 29.30 — — 6 Octyl Phosphate (20%) Linoleic Acid (80%) 3.10 0.32 62.67 28.67 — — C-7 — Linoleic Acid (100%) 0.00 0.30 62.43 28.57 27 13 Table 9 Example 6: Evaluation of the combination of a monophosphoric ester and an oil.

[00133] Table 10 illustrates the effect of combining a monophosphoric ester and an oil. Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (PPm) As (PPm) Reference Composition Floated (Rejected) Content (%) in concentrate Petition 870260070396, dated 07 / 15 / 2026, pages 36 / 39 28 / 30 Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (ppm) As (ppm) 1 Octyl phosphate (100%) — 23.29 0.33 71.32 32.64 8 4 2 Octyl phosphate (90%) Sunflower oil (10%) 13.30 0.3 68.98 31.56 3 Octyl phosphate (80%) Sunflower oil (20%) 11.34 0.29 69.30 31.71 — — 4 Octyl phosphate (70%) Sunflower oil (30%) 10.20 0.29 67.50 30.88 — — 5 Octyl phosphate (60%) Sunflower oil (40%) 6.59 0.29 65.12 29.79 — — 6 Octyl phosphate (50%) Sunflower oil (50%) 5.73 0.29 64.34 29.44 — — 7 Octyl phosphate (40%) Sunflower oil (60%) 4.58 0.30 63.05 28.85 — — C-8 Octyl phosphate (30%) Sunflower oil (70%) 0.00 0.30 62.43 28.57 27 13 C-9 Octyl phosphate (20%) Sunflower oil (80%) 0.00 0.30 62.43 28.57 27 13 C-10 Octyl phosphate (10%) Sunflower oil (90%) 0.00 0.30 62.43 28.57 27 13 C-11 — Sunflower oil (100%) 0.00 0.30 62.43 28.57 27 13 Table 10 Example 7: Evaluation of the combination of a monophosphoric ester and a SULFONATE

[00134] Table 11 illustrates the effect of combining a monophosphoric ester and a sulfonate. Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (PPm) As (PPm) Reference Composition Floated (Rejected) Content (%) in concentrate 1 Octyl phosphate (100%) — 23.29 0.33 71.32 32.64 8 4 3 Octyl phosphate (80%) Dodecylbenzene sulfonic acid (20%) 16.01 0.30 71.07 32.52 8 4 5 Octyl phosphate (60%) Dodecylbenzene sulfonic acid (40%) 12.56 0.30 70.03 32.04 8 4 Table 11 Example 8: Evaluation of the combination of a monophosphoric ester and an ether. PEGYLATED

[00135] Table 12 illustrates the effect of combining a monophosphoric ester and a pegylated ether. Petition 870260070396, dated 07 / 15 / 2026, pp. 37 / 39 29 / 30 Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (PPm) As (PPm) Reference Composition Floated (Rejected) Grade (%) in concentrate 1 Octyl phosphate (100%) ___ 23.29 0.33 71.32 32.64 8 4 2 Octyl phosphate (90%) IGEPAL CA630 (10%) 22.83 0.32 71.38 32.66 7 4 3 Octyl phosphate (80%) IGEPAL CA630 (20%) 20.69 0.32 70.72 32.36 8 4 4 Octyl phosphate (70%) IGEPAL CA630 (30%) 18.00 0.31 70.99 32.48 8 4 5 Octyl phosphate (60%) IGEPAL CA630 (40%) 18.16 0.32 68.98 31.56 ___ ___ Table 12 Example 9: Evaluation of the combination of a monophosphoric ester and an ester diphosphoric

[00136] The characterization and quantification of the phosphate ore samples used in Example 9 were performed using the techniques described above, including atomic absorption and ICP-MS. The results are presented in Table 13 below. P2O5 (%) CO2 (%) MgO (%) SiO2 (%) Cd (ppm) 21.83 8.85 1.84 22.62 15 Table 13: Characterization of the ore sample used in example 9

[00137] Phosphate ore contains heavy metals, especially cadmium, 15 ppm.

[00138] The monoester of phosphoric acid is octyl phosphate (mono-octylphosphoric ester). The diester of phosphoric acid is dioctyl phosphate (dioctylphosphoric ester).

[00139] The phosphate ore is treated as described in paragraph 3.1.

[00140] Table 14 shows the effect of combining the monoester with a linear C8 chain and a diester with linear C8 chains. Petition 870260070396, dated 07 / 15 / 2026, pp. 38 / 39 30 / 30 Flotation Method Collector Flotation Recovery (%) MgO (%) BPL (%) P2O5 (%) Cd (ppm) Reference Composition Floated (Rejected) Content (%) in concentrate 1 Octyl phosphate (100%) ___ 24.70 0.33 71.32 32.64 8 2 Octyl phosphate (95%) Dioctyl phosphate (5%) 25.81 1.00 61.37 28.09 15 3 Octyl phosphate (90%) Dioctyl phosphate (10%) 26.23 1.00 62.09 28.42 16 3 Octyl phosphate (80%) Dioctyl phosphate (20%) 27.76 0.90 62.40 28.56 17 4 Octyl phosphate (60%) Dioctyl phosphate (40%) 28.04 0.93 64.24 29.40 15 5 Octyl phosphate (40%) Dioctyl phosphate (60%) 24.53 1.21 61.38 28.09 15 6 Octyl phosphate (20%) Dioctyl phosphate (80%) 21.69 1.60 59.44 27.20 15 7 — Dioctyl phosphate (100%) 17.45 1.91 56.37 25.80 15 Table 14

[00141] The presence of diester in the collector leads to a decrease in efficiency. Petition 870260070396, dated 07 / 15 / 2026, page 39 / 39

Claims

1 / 3 Claims 1. METHOD FOR TREATING PHOSPHATE ORES containing heavy metals by reverse flotation, characterized in that the method comprises the following steps: - (i) adding to an aqueous suspension of phosphate ore a monophosphoric ester A of formula (I): Ri - O - P(=O) - (OH)2 (I) wherein R1 is a saturated or unsaturated, linear or branched hydrocarbon chain comprising 6 to 10 carbon atoms, preferably an alkyl group, alone or mixed with a compound B chosen from the group consisting of: a monophosphoric ester of formula (II) R2 - O - P(=O) - (OH)2 (II) wherein R2 is a saturated or unsaturated, linear or branched hydrocarbon chain comprising 6 to 18 carbon atoms, preferably an alkyl group, different from the R1 group of the monophosphoric ester A of formula (i) an alcohol, a fatty acid, a fixed oil, a sulfate, a sulfonate, an ether, and mixtures thereof; - (ii) injecting gas into the aqueous suspension to form foam;and - (iii) remove foam and recover the aqueous suspension from the treated ore. Petition 870250071788, dated 08 / 14 / 2025, pp. 80 / 84 2 / 3; 2. METHOD, according to claim 1, characterized in that the Ri group of the monophosphoric ester A of formula (I) is a linear alkyl group comprising 8 or 9 carbon atoms or a branched alkyl group comprising 8 or 9 carbon atoms.

3. METHOD, according to any one of claims 1 to 2, characterized in that compound B, when present, is an alcohol of formula R3-OH (III), wherein R3 is a saturated or unsaturated, linear or branched hydrocarbon chain comprising from 2 to 20 carbon atoms, preferably from 6 to 10 carbon atoms, preferably an alkyl group.

4. METHOD, according to any one of claims 1 to 2, characterized in that compound B, when present, is: a salt of a hydrocarbon chain sulfonic acid, or a salt of an aromatic sulfonic acid substituted with a hydrocarbon chain, the hydrocarbon chain being saturated or unsaturated, linear or branched, comprising from 2 to 20 carbon atoms, preferably an alkyl group, compound B being preferably the sodium salt of dodecylbenzenesulfonic acid; or is a hydrocarbon chain sulfate, the hydrocarbon chain being saturated or unsaturated, linear or branched, comprising from 2 to 20 carbon atoms, preferably an alkyl sulfate, preferably sodium dodecyl sulfate.

5. METHOD, according to any one of claims 1 to 2, characterized in that compound B, when present, is an ether, pegylated or not, of formula R5-(OC2H4)nOR6 (IV) with R5 being an alkyl or aromatic or alkylated aromatic group and R6 being an alkyl group or a hydrogen atom and n represents an integer ranging from 0 to 10.

6. METHOD, according to any of the claims Petition 870250071788, dated 08 / 14 / 2025, p. 81 / 84 3 / 3 1 to 5, characterized by the amount of monophosphoric ester A and compound B added during step (i) varying from 100 g to 500 g per tonne of phosphate ores, preferably 100 g to 300 g.

7. METHOD, according to any one of claims 1 to 6, characterized by further comprising a step i') before step i) of adding a depressant, such as phosphoric acid, and / or a step i'') between step i) and step ii) of adding an amine compound for silicate flotation.

8. USE OF MONOPHOSPHORIUM ESTER A alone or in combination with compound b, as defined in any of claims 1 to 6, characterized by being for the treatment of phosphate ores containing heavy metals. Petition 870250071788, dated 08 / 14 / 2025, pp. 82 / 84

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