Method for purifying a filtrate from leaching of black mass from spent lithium-ion batteries

Abstract

The present invention relates to a method for purifying a filtrate from leaching of black mass from spent lithium-ion batteries and / or lithium-ion battery production scrap, said filtrate containing at least one valuable metal to be recovered and at least one impurity chosen from aluminum alone or as a mixture with calcium and / or fluorine, said method comprising the following steps: a) increasing, in the presence of a source of phosphates and optionally a redox compound, the pH of the filtrate from leaching of black mass from spent lithium-ion batteries and / or lithium-ion battery production scrap, said leaching filtrate containing at least one valuable metal and at least one impurity chosen from aluminum alone or as a mixture with calcium and / or fluorine; b) adding a source of fluorides.

Description

Process for purifying a leaching filtrate from the black mass of used lithium-ion batteries Technical Field

[0001] The present invention relates to the general field of recycling used lithium-ion batteries and / or lithium-ion battery production waste and in particular the recovery of valuable metals present in these batteries, such as lithium, cobalt, nickel, manganese and their mixtures.

[0002] It relates more particularly to the purification of the leaching filtrate from the black mass of used lithium-ion batteries and / or lithium-ion battery production waste in order to remove impurities and recover the valuable metal(s). Prior art

[0003] When recycling used lithium-ion batteries, after separating the plastics, the metal parts containing the electrodes such as the battery cells are crushed or shredded to produce a powdery metal fraction called "black mass".

[0004] Similarly, during the lithium-ion battery manufacturing process, semi-finished products such as active material powders or non-compliant batteries considered as production waste (also called "scraps") may be produced which should be recycled. These products can be treated in the same way as used lithium-ion batteries and will contribute to the production of the metallic powder fraction called "black mass".

[0005] It is generally known to dissolve the black mass in sulfuric acid in the presence of an oxidative-reducing reagent in order to maximize the dissolution yield and thus obtain a leachate which, after the implementation of a liquid / solid separation step, is called leaching filtrate.

[0006] This leaching filtrate of the black mass contains many valuable metals such as lithium, nickel, cobalt and / or manganese which are of interest to recover but also many impurities such as aluminum, calcium, iron, fluorine, phosphorus and / or copper that need to be removed. It is therefore necessary to find methods to separate valuable metals from impurities in order to recover them.

[0007] Patent application WO2018 / 184876 describes a method for recovering lithium from used batteries comprising the addition of a source of phosphates to the leach filtrate after neutralization to a pH between 2 and 4 in order to remove aluminum and iron. However, this method does not address other impurities that may be present in the leach filtrate, such as fluorine. Furthermore, this method does not allow for optimal removal of aluminum.

[0008] The inventors realized that it was possible to improve this purification without significant loss of valuable metals by adding a fluoride source after the addition of the phosphate source. This makes it possible to obtain a two-step purification process with a better purification efficiency than that of the process described in application WO2018 / 184876 thanks to the selective precipitation of the impurities present. Statement of the invention

[0009] The present invention therefore relates to a method for purifying a leaching filtrate from the black mass of used lithium-ion batteries and / or lithium-ion battery production scrap, said filtrate containing at least one valuable metal to be recovered, advantageously chosen from lithium, nickel, cobalt, manganese and mixtures thereof, and at least one impurity chosen from aluminum, alone or mixed with fluorine and / or calcium, said method comprising the following steps: a) increasing, in the presence of a source of phosphates and optionally of an oxidation-reduction compound, the pH of the leaching filtrate from the black mass of used lithium-ion batteries and / or lithium-ion battery production scrap, advantageously to a pH of between 2 and 5, in particular of between 3 and 4, said leaching filtrate containing at least one valuable metal, advantageously chosen from lithium, nickel, cobalt, manganese and their mixtures,and at least one impurity chosen from, aluminum, alone or mixed with fluorine and / or calcium; b) addition of a source of fluorides.

[0010] In this application, the expressions "between ... and ...", "from ... to ..." and "in the range >......", must be understood to include limits unless explicitly stated otherwise.

[0011] For the purposes of the present invention, the term "black mass" or "black mass" means the powdery fraction containing fine metal particles obtained after separation of plastic materials and grinding / processing of parts containing electrodes such as battery cells, used lithium-ion batteries and / or lithium-ion battery production scrap. Typically, the black mass is obtained by screening to 500 μm or less. There are two main processing routes used for the production of the black mass: - heat treatment processes at temperatures > 400 °C. The ground material of batteries and / or battery production scrap can be heated in an inert atmosphere or in air. A black mass called "thermal black mass" or "thermal black mass" is obtained. The thermal black mass generally exhibits reducing behavior during leaching, with generally an oxidation-reduction potential less than or equal to 600 mV vs Ag / AgCI, more advantageously between -300 and 600 mV vs Ag / AgCI, in particular -300 mV vs Ag / AgCI and - high-intensity mechanical treatments. A black mass called "mechanical black mass" or "mechanical black mass" is obtained. The mechanical black mass generally exhibits oxidizing behavior during leaching, with a redox potential generally in the range of +1000 mV to +1200 mV vs Ag / AgCl. In particular, the mechanical mass has not undergone heat treatment at a temperature above 400 °C.

[0012] The black mass contains many valuable metals such as lithium, nickel, cobalt and / or manganese and many impurities such as aluminum, calcium, iron, fluorine, phosphorus and / or copper. It may also contain magnesium. It also contains graphite. The black mass contains little or no polymeric materials since these have were removed upstream of the process to manufacture the black mass. The typical composition of a black mass (thermal or mechanical) apart from the carbon content is shown in Table 2 of Example 1.

[0013] For the purposes of the present invention, the term "black mass leaching filtrate" means the liquid part resulting from the leaching of the black mass. In general, the leaching is carried out with sulfuric acid in the presence of an oxidizing-reducing compound and the leaching step is followed by a liquid / solid separation step (advantageously by filtration) in order to recover the liquid part, thus called the black mass leaching filtrate. Advantageously, the leaching filtrate according to the invention has undergone a prior iron removal step after the liquid / solid separation step, in particular by precipitation.

[0014] The leaching filtrate of the black mass according to the invention, more simply called "leaching filtrate" in the remainder of the application, contains at least one valuable metal to be recovered. It may thus be lithium, nickel, manganese and / or cobalt. Advantageously, it is a mixture of lithium (Li), nickel (Ni), manganese (Mn) and cobalt (Co), more advantageously lithium alone or in a mixture with nickel, manganese and / or cobalt. The nickel, cobalt, manganese and / or lithium contents of the leaching filtrate according to the invention depend on the contents present in the black mass.

[0015] The lithium content of the leaching filtrate according to the invention, if lithium is present, can thus be < 15g / l, more advantageously between 5g / l and 14g / l, in particular between 9g / l and 11g / l.

[0016] The nickel content of the leaching filtrate according to the invention, if nickel is present, can thus be in the range 10-60 g / l, more advantageously between 30 g / l and 55 g / l, in particular between 44 g / l and 48 g / l.

[0017] The cobalt content of the leaching filtrate according to the invention, if cobalt is present, can thus be in the range 1-40 g / l, more advantageously between 5 g / l and 20 g / l, in particular between 12 g / l and 15 g / l.

[0018] The manganese content of the leaching filtrate according to the invention, if manganese is present, may be < 50 g / l, more advantageously between 5 g / l and 30 g / l, in particular between 12 g / l and 15 g / l.

[0019] The leaching filtrate according to the invention contains at least one impurity to be removed. This is aluminum (Al), alone or in a mixture with fluorine (F) and / or calcium (Ca), more particularly aluminum, alone or in a mixture with fluorine, even more particularly a mixture of aluminum and fluorine. The contents of aluminum (Al), calcium (Ca), and / or fluorine (F) in the leaching filtrate according to the invention depend on the contents present in the black mass.

[0020] The aluminum content of the leaching filtrate according to the invention can thus be < 20g / l, more advantageously between 1 g / l and 10 g / l, in particular between 2 g / l and 4g / l.

[0021] The calcium content of the leaching filtrate according to the invention, if calcium is present, can thus be < 0.7 g / lg / l, more advantageously between 0.2 g / l and 0.6 g / l, in particular between 0.3 g / l and 0.5 g / l.

[0022] The fluorine content of the leaching filtrate according to the invention, if fluorine is present, can thus be < 20 g / l, more advantageously between 4 g / l and 10 g / l, in particular between 6 g / l and 8 g / l.

[0023] The leaching filtrate according to the invention may contain other impurities such as magnesium (Mg), iron (Fe), phosphorus (P) and / or copper (Cu), advantageously it contains phosphorus and / or copper. Indeed, advantageously the iron has been eliminated during a specific prior step.

[0024] The magnesium content of the leaching filtrate according to the invention, if magnesium is present, can thus be < 5 g / l, more advantageously between 3 g / l and 4 g / l.

[0025] The iron content of the leaching filtrate according to the invention, if iron is present, can thus be < 10 g / l, more advantageously between 0.5 g / l and 5 g / l, in particular between 1 g / l and 2 g / l. Advantageously, when the iron has been removed during a specific preliminary step, its content can thus be < 0.1 g / l and preferably < 0.01 g / l.

[0026] Phosphorus content in the form of PO4 3 ' of the leaching filtrate according to the invention, if phosphorus is present, can thus be < 10 g / l, more advantageously between 0.1 g / l and 5 g / l, in particular between 0.5 g / l and 4 g / l.

[0027] The copper content of the leaching filtrate according to the invention, if copper is present, can thus be < 30 g / l, more advantageously between 2 g / l and 20 g / l, in particular between 9 g / l and 11 g / l.

[0028] Advantageously, the leaching filtrate according to the invention has an initial pH of between 0.5 and 2.5, in particular between 0.5 and 1.5. More advantageously, it is 1.

[0029] For the purposes of the present invention, the term "initial pH of the leaching filtrate" means the pH of the leaching filtrate before implementing step a).

[0030] Advantageously, the leaching filtrate according to the invention has an initial redox potential of less than 700 mV vs Ag / AgCI, more advantageously of less than 600 mV vs Ag / AgCI.

[0031] For the purposes of the present invention, the term "initial redox potential of the leaching filtrate" means the redox potential of the leaching filtrate before the implementation of step a).

[0032] The method according to the invention therefore comprises at least two steps, a) and b). These two steps are advantageously successive.

[0033] Thus, step a) of the process according to the invention consists of an increase, in the presence of a source of phosphates, of the pH of the leaching filtrate according to the invention, advantageously to a pH of between 2 and 5, in particular between 3 and 4, more advantageously between 3.3 and 3.5. This step allows the selective precipitation of a portion of the impurity(ies) present in the form of phosphates, while avoiding excessive precipitation of the valuable metal(s). However, if the pH is greater than 5, nickel and cobalt precipitate significantly and there is too great a loss of valuable metals.

[0034] In an advantageous embodiment, step a) is carried out by adding a base such as soda, lime, limestone, magnesia (MgO), advantageously soda or lime, in particular lime, more particularly milk of lime.

[0035] Advantageously, the source of phosphates in step a) of the process according to the invention is chosen from sodium phosphate (Na3PO4), sodium hydrogen phosphate (Na2HPO4), sodium dihydrogen phosphate (NaH2PO4), lithium phosphate (l_i3PO4), ammonium phosphate (NH4)3PO4, potassium phosphate (K3PO4), potassium dihydrogen phosphate (KH2PO4), potassium hydrogen phosphate (K2HPO4), tricalcium phosphate (Ca3(PO4)2), monocalcium phosphate (Ca(H2PO4)2), dicalcium phosphate (CaHPO4), dicalcium diphosphate (Ca2(PO3-O-PO3), phosphoric acid (H3PO4) and mixtures thereof, more advantageously chosen from sodium phosphate (Na3PO4), lithium phosphate (l_i3PO4) and mixtures thereof. mixtures, even more advantageously it is lithium phosphate (Li3PO4).

[0036] The quantity in moles of phosphate source will depend on the quantities in moles of the impurity(ies) present in the leaching filtrate according to the invention. Thus, advantageously, the leaching filtrate according to the invention comprises iron and / or aluminum and the quantity in moles of phosphate source used in step a) is adjusted to correspond to a PO47(AI) molar ratio of between 70% and 110%, more advantageously between 70% and 90%.

[0037] In the case where the leaching filtrate according to the invention comprises iron, which is not the preferred variant of the process, step a) is carried out in the presence of an oxidoreducing compound, advantageously chosen from peroxodisulfates S2O8 2, sulfur oxides (SO2), hydrogen peroxide (H2O2) and mixtures thereof. More advantageously, it is an oxidizing compound, even more advantageously hydrogen peroxide (H2O2). In particular, the redox compound is present in a content necessary to maintain the redox potential of step a) at a value greater than 100 mV vs Ag / AgCI, advantageously between 500 mV vs Ag / AgCI and 800 mV vs Ag / AgCI, more advantageously at a value of 600 mV vs Ag / AgCl. The threshold value of 100 mV vs Ag / AgCl allows the iron (III) to begin to precipitate and therefore to be eliminated from the leaching filtrate according to the invention during step a).

[0038] In an advantageous embodiment, the temperature of step a) is between 20°C and 95°C, advantageously between 30°C and 90°C, more advantageously between 45°C and 85°C, in particular between 50°C and 80°C.

[0039] In an advantageous embodiment, the duration of step a) is at most 8 hours, advantageously between 30 minutes and 4 hours, more advantageously it is 1 hour.

[0040] In an advantageous embodiment, step a) of the method according to the invention comprises the following steps: -al) addition of the phosphate source; - a2) optional addition of the redox compound, advantageously so as to maintain the redox potential at a value greater than 100 mV vs Ag / AgCI; - a3) increase in pH, advantageously to a value between 2 and 5.

[0041] Steps a1), a2 and a3) may be successive or simultaneous. Advantageously, they are successive. In particular, steps a1) and a2) (if step a2) is present) are simultaneous and steps a1) and a3) or a2) and a3) are successive.

[0042] At the end of step a) (or step a3), a mixture of solid (obtained by precipitation) containing the impurity(ies) and liquid containing the valuable metal(s) and a quantity depleted in impurities is thus obtained. According to the present invention, the term "quantity depleted in impurities" means a quantity lower in impurity than the quantity initially present before the implementation of the step.

[0043] Step b) of the process according to the present invention consists of adding a source of fluorides to the product obtained in step a), in particular to the liquid part of the product obtained in step a). This step allows the selective precipitation in the form of fluorides of a part of the impurity(ies) still present in the liquid part while avoiding excessive precipitation of the metal or valuable metals.

[0044] Advantageously, the source of fluorides in step b) is chosen from HF, NaF, LiF, KF, MgF2, CaF2, NiF, CoF, MnF and their mixtures, advantageously it is NaF.

[0045] The quantity in moles of fluoride source will depend on the quantities in moles of the impurity(ies) present in the liquid part of the product obtained in step a) of the process according to the invention. Thus, advantageously, the liquid part of the product obtained in step a) according to the invention comprises aluminum and / or calcium, advantageously only aluminum, and the quantity in moles of fluoride source used in step b) is adjusted to correspond to a molar value of fluorine of between 1 and 10 times, advantageously between 4 and 7 times, the quantity in moles of aluminum and / or up to twice the quantity in moles of calcium present in the liquid part obtained in step a).

[0046] In an advantageous embodiment, the liquid part of the product obtained in step a) comprises iron and, during step b) according to the invention, the redox potential is adjusted to a value greater than 100 mV vs Ag / AgCI, advantageously between 500 mV vs Ag / AgCI and 800 mV vs Ag / AgCI, more advantageously to a value of 600 mV vs Ag / AgCI, in particular by adding an redox compound, advantageously chosen from peroxodisulfate S2O8 2 , sulfur oxides (SO2), hydrogen peroxide (H2O2) and mixtures thereof. More advantageously it is an oxidizing compound, even more advantageously hydrogen peroxide. The threshold value of 100mv vs Ag / AgCl allows iron (III) to begin to precipitate and therefore to be eliminated from the liquid part of the product obtained in step a).

[0047] In another advantageous embodiment, during step b) according to the invention, the pH is adjusted to a value between 1 and 5, advantageously between 3 and 4, in particular to a pH of 3.8. Indeed, if the pH is higher than 5, nickel and cobalt precipitate significantly and there is a large loss of valuable metals. This pH adjustment can be done by adding a base such as that soda, lime, limestone, magnesia (MgO), advantageously soda or lime, in particular soda.

[0048] In an advantageous embodiment, the temperature of step b) is between 20°C and 95°C, advantageously between 30°C and 90°C, more advantageously between 45°C and 85°C, in particular between 50°C and 80°C.

[0049] In an advantageous embodiment, the duration of step b) is at most 6 hours, advantageously between 1 hour and 4 hours, more advantageously it is 3 hours.

[0050] In another advantageous embodiment, step b) further comprises the addition of an iron source, in particular a soluble iron source such as iron sulfate, iron chloride and / or iron nitrate, more particularly iron sulfate, advantageously in a mole content corresponding to an Fe / P molar ratio of at least 100%.

[0051] In a particularly advantageous embodiment, step b) of the method according to the invention comprises the following steps: - bl) addition of the fluoride source; - b2) optional addition of iron source; - b3) optional adjustment of the redox potential to a value greater than 100 mV vs Ag / AgCl, in particular by adding an redox compound; - b4) adjustment of the pH to a value between 1 and 5, in particular by adding a base.

[0052] Steps bl), b2), b3) and b4) may be successive or simultaneous. Advantageously, they are successive.

[0053] The method according to the present invention may further comprise a step c) of liquid / solid separation of the product obtained in step b) so as to obtain a liquid containing the at least one valuable metal and depleted in impurities and a solid containing the at least one impurity. This step may be carried out by any liquid / solid separation methods known to man. of the trade such as filtration, decantation, centrifugation etc. Advantageously, this involves filtration, particularly under vacuum.

[0054] The method according to the present invention may comprise, between steps a) and b), an intermediate step a4) of liquid / solid separation of the product obtained in step a). In this case, step b) is carried out on the liquid part resulting from step a4). This step a4) may be carried out by any liquid / solid separation methods known to those skilled in the art, such as filtration, decantation, centrifugation, etc. Advantageously, it is a filtration, in particular under vacuum, and the liquid part of step a4) is therefore the filtrate.

[0055] In an advantageous embodiment, the method according to the invention comprises, prior to step a), a preliminary step alpha) of decoppering the leaching filtrate according to the invention. In this case, step a) is carried out on the copper-depleted leaching filtrate obtained in step alpha). Step alpha) according to the invention can be carried out by any method known to those skilled in the art, in particular by precipitation of the copper sulfide so as to obtain a copper-depleted leaching filtrate, more particularly by addition of sodium hydrogen sulfide (NaHS) and / or Na2S and / or H2S. In particular, step alpha) comprises a liquid / solid separation step after the precipitation of the copper so as to recover a copper-depleted liquid portion, also referred to in the present application as "copper-depleted leaching filtrate".The liquid / solid separation step can be implemented by any liquid / solid separation methods known to those skilled in the art such as filtration, decantation, centrifugation, etc. Advantageously, it is a filtration, more advantageously under vacuum.

[0056] In an advantageous embodiment, the temperature of step alpha) is between 20°C and 95°C, advantageously between 30°C and 90°C, more advantageously between 45°C and 85°C, in particular between 50°C and 80°C.

[0057] In an advantageous embodiment, the duration of step alpha) is at most 12 hours, advantageously between 1 hour and 5 hours, more advantageously it is 2 hours.

[0058] Advantageously, the mass yield of precipitation of the copper from step alpha) (calculated according to the following formula: mass of copper (in g) in solid form obtained in step alpha) / initial mass of copper (in g) in the leaching filtrate before step alpha) is greater than 90%, in particular greater than 95%, more particularly greater than 99%, even more particularly greater than 99.5%, for example equal to 99.9%.

[0059] Advantageously, the mass precipitation yield of the process according to the invention (steps a), b) and possibly steps alpha) and / or a4) and / or c)) (calculated according to the following formula: mass of element (in g) in solid form obtained at the end of the process / initial mass of element (in g) in the leaching filtrate before step a): - in aluminum is greater than 95%, in particular greater than 99%, more particularly greater than 99.5%, even more particularly greater than 99.9%, and / or - calcium is greater than 40%, in particular greater than 45%, more particularly greater than 47%, even more particularly greater than 50% and / or - fluorine is greater than 85%, in particular greater than 87%, more particularly greater than 90%, and / or - iron (in particular in the case where the oxidation-reduction potential is adjusted during steps a) and b)) is greater than 90%, in particular greater than 95%, more particularly greater than 97%, even more particularly greater than 99%, and / or - in phosphorus is greater than 92%, in particular greater than 95%, more particularly greater than 97%, even more particularly greater than 99%, and / or - cobalt is less than 2%, in particular less than 1%, and / or - nickel is less than 2%, in particular less than 1%, and / or - lithium is less than 10%, in particular less than 5% and / or - manganese is less than 2%, in particular less than 1%.

[0060] The method according to the invention may comprise, prior to the optional step alpha) and step a), a step A) of leaching a black mass in order to obtain a leaching filtrate. In particular, the black mass may be a mixture of thermal black mass and mechanical black mass, in particular in a mass ratio of 50 / 50. Advantageously, this step A) is carried out by a method well known to those skilled in the art, advantageously using an acid, such as sulfuric acid H2SO4. Advantageously, the quantity in moles of acid is calculated to correspond to a molar ratio H + / (Li+Co+Ni+Mn) necessary for the dissolution of lithium, cobalt, manganese and / or nickel present in the black mass, in particular between 90 and 150%, preferably between 110 and 130%. In particular the pH is less than 2. More particularly the temperature is greater than 50°C, in particular greater than 70°C, more particularly it is 90°C. Advantageously, step A) lasts 4 hours. Advantageously, step A) is carried out in the presence of an oxidation-reduction compound, in particular a reducing compound, more advantageously chosen from hydrogen peroxide, SO2 in gas form and their mixtures, in particular, it is SO2 in gas form. In particular, the content of redox compound used is that necessary to adjust the redox potential in a range between 200 and 800 mV vs Ag / AgCI, more advantageously between 200 and 700 mV vs Ag / AgCI, more particularly between 200 and 600 mV vs Ag / AgCI.In an advantageous embodiment, the acid is added to a first reactor and the redox compound to a second reactor. The leaching mass yield of nickel and / or lithium and / or cobalt and / or manganese (calculated according to the following formula: 1 - mass of the element (in g) in solid form obtained at the end of step A) / initial mass of element (in g) in the filtrate before step A) is advantageously greater than 90%, more advantageously greater than 95%, even more advantageously greater than 99%.

[0061] The valuable metal or metals present in the liquid part obtained with the process according to the invention can be recovered and separated by methods well known to those skilled in the art, in particular by solvent extraction.

[0062] The present invention will be better understood upon reading the description of the examples which follow. The examples are given for informational purposes only and are not limiting. Unless otherwise stated in the examples, the pressure is atmospheric pressure and the temperatures are indicated in °C, EXAMPLE Example 1: Implementation of steps A), alpha), a), a4), b) and c) of the process according to the invention. r00631Step A): leaching

[0064] The following data relate to the leaching of black mass by H2SO4 at 90°C for 4 hours. The black mass mixture (thermal black mass + mechanical black mass) is dissolved in water, the whole is brought to temperature and then the acid is added. The quantity of acid added (54g) is calculated to correspond to a fraction of the stoichiometric quantity necessary for the dissolution of the sum in moles Li+Ni+Mn+Co, in particular at a molar ratio H + / (Li+Co+Ni+Mn) between 90% and 150%, preferably between 110% and 130%, in particular 120%. The tests last 4 hours in total, the addition of acid is done in a first reactor (reactor 1) and the addition of a reducing agent in the form of gaseous SO2 is carried out in a second reactor (reactor 2). The aim is to adjust the redox potential in a range between 200 and 800 mV (vs Ag / AgCI). Thus, the step consists of the leaching of 100 g of black mass (50 g of thermal black mass and 50 g of mechanical black mass) and the addition of SO2 in order to change the redox potential from a value close to 1100 mV vs Ag / AgCI to a value lower than 600 mV vs Ag / AgCI.

[0065] The following Table 1 shows the data concerning this step:

[0066] [Table 1]

[0067] The typical composition of mechanical or thermal black mass in valuable metal and impurity (apart from carbon) is gathered in the following table 2:

[0068] [Table 2]

[0069] The product obtained is filtered under vacuum. This gives a leaching filtrate having the composition indicated in the following table 3:

[0070] [Table 3]

[0071] [EtaDe alpha]: décuiyraqe

[0072] The leaching filtrate obtained in step A) is decoppered by sulfurization using a sodium hydrogen sulfide (NaHS) solution. The filtrate is mixed with the NaHS solution, kept at a temperature of 50 °C for 2 h and then filtered.

[0073] The following Table 4 shows the data concerning this step:

[0074] [Table 4] Quantity | Quantity | Temperature! Time | pH | pH | Potential | Potential | Mass yield |

[0075] The mass yield of copper precipitation from step alpha) is calculated according to the following formula: mass of copper (in g) in solid form obtained in step alpha) / mass of copper (in g) initially in the leaching filtrate before step alpha. The product obtained is filtered under vacuum. This gives a filtrate having the composition indicated in the following table 5:

[0076] [Table 5]

[0077] Steps a) and a4): increase in pH in the presence of a phosphate source and an oxidizing-reducing compound then filtration

[0078] 500 ml of the filtrate obtained in step alpha) is used. It has an initial pH of 1. The filtrate is mixed with the phosphate source (Li3PO4) to correspond to a molar ratio PO47(AI) between 90% and 110%. The potential is then adjusted to around 600 mV (vs Ag / AgCl) with hydrogen peroxide. Finally, the pH is adjusted with 10% lime milk to a target between 2.5 and 3.5 in order to selectively precipitate aluminum, iron, copper, calcium and fluorine. The reaction is maintained at a temperature of 80°C for at least 1 h, then filtered under vacuum.

[0079] The following Table 6 shows the data concerning this step:

[0080] [Table 6]

[0081]

[0082] Steps b) and c): addition of a fluoride source and filtration

[0083] 500 ml of the filtrate obtained in step a4) is used. It is mixed with the fluoride source (LiF) to correspond to a molar value of fluorine between 4 and 7 times the amount in moles of aluminum in solution and up to twice that in moles of calcium. The potential is then adjusted around 600 mV (vs Ag / AgCl) with hydrogen peroxide. Finally, the pH is adjusted to a target between 3 and 4 using a 10% by mass sodium hydroxide solution in order to selectively precipitate aluminum, iron, calcium and fluorine. The reaction is maintained at a temperature of 80 ° C for 3 h, then filtered under vacuum.

[0084] The following Table 7 shows the data concerning this step:

[0085] [Table 7]

[0086] The cumulative precipitation mass yield in % after steps a) to c) above is presented in Table 8 below and is calculated using the following formula: mass of element (in g) in solid form obtained from the process / initial mass of element (in g) in the leaching filtrate before step a):

[0087] [Table 8]

[0088] The process according to the invention therefore makes it possible to selectively precipitate aluminum, calcium, copper, fluorine and iron.

[0089] Step b) and c): addition of a source of fluorides and a source of iron and filtration

[0090] 500 ml of the filtrate obtained in step a4) is used. It is mixed with the fluoride source (LiF) to correspond to a fluorine molar value between 4 and 7 times the amount in moles of aluminum in solution and up to twice that in moles of calcium, then with an iron source (iron sulfate) corresponding to a Fe / P molar ratio of at least 100%. The potential is then adjusted to around 600 mV (vs Ag / AgCl) with hydrogen peroxide. Finally, the pH is adjusted to a target between 3 and 4 using 10% sodium hydroxide in order to selectively precipitate aluminum, iron, calcium, phosphorus and fluorine. The reaction is maintained at a temperature of 80°C for 3 h, then filtered under vacuum.

[0091] The following Table 9 shows the data concerning this step:

[0092] [Table 9]

[0093] The cumulative precipitation mass yield in % after steps a) to c) above is presented in the following table 10 and is calculated according to the following formula: mass of element (in g) in solid form obtained at the end of the process / initial mass of element (in g) in the leaching filtrate before step a):

[0094] [Table 10]

[0095] The process according to the invention therefore makes it possible to selectively precipitate aluminum, calcium, copper, fluorine, phosphorus and iron. Comparative example 1: implementation of steps A), alpha), a) and a4) of the method according to the invention.

[0096] Steps A), alpha), a) and a4) of Example 1 have been implemented.

[0097] The cumulative precipitation mass yield in % after steps a) and a4) is presented in the following table 11 and is calculated according to the following formula: mass of element (in g) in solid form obtained at the end of step a4) / initial mass of element (in g) in the leaching filtrate before step a):

[0098] [Table 11]

[0099] The precipitation yield of Al, F and P is less good than with the process according to the invention. Comparative example 2: implementation of steps A), alpha), b) and c) of the method according to the invention.

[0100] Steps A), alpha), b) and c) of example 1 were carried out without adding an iron source and steps b) and c) were carried out directly on the filtrate obtained in step alpha).

[0101] The cumulative precipitation mass yield in % after steps b) and c) is presented in the following table 12 and is calculated according to the following formula: mass of element (in g) in solid form obtained at the end of step c) / initial mass of element (in g) in the leaching filtrate before step b):

[0102] [Table 12]

[0103] The precipitation yield of P and Li is less good than with the process according to the invention. Example 2: implementation of steps A), alpha), a), a4), b) and c) of the process according to the invention with prior elimination of iron between steps alpha) and a).

[0104] Iron removal: 500 ml of the filtrate obtained in step alpha) of Example 1 is used. It has an initial pH between 1 and 2. Hydrogen peroxide is added to the filtrate to reach the potential of 600 mV (vs Ag / AgCl). Finally, the pH is adjusted with 10% milk of lime to a target between 3.3 and 3.6 in order to precipitate the iron. The reaction is maintained at a temperature of 60 °C for at least 1 h, then filtered under vacuum. The following Table 13 shows the data for this step: [Table 13]

[0105] The cumulative precipitation mass yield in % after the above step is presented in Table 14 below and is calculated according to the following formula: mass of element (in g) in solid form obtained at the end of the step / initial mass of element (in g) in the leaching filtrate before the above step: [Table 14]

[0106] Steps a) and a4) according to the invention: 500 ml of the filtrate obtained in the previous step is used. It has an initial pH of 3.5. The filtrate is mixed with the phosphate source (Na3PO4) to correspond to a PO47(AI) molar ratio of between 80% and 100%. Finally, the pH is adjusted with 10% milk of lime to a target of between 3.8 and 4.2 in order to selectively precipitate aluminum, copper, calcium and fluorine. The reaction is maintained at a temperature of 60 °C for at least 1 h, then filtered under vacuum. The following Table 15 shows the data concerning this step: [Table 15]

[0107] The cumulative precipitation mass yield in % after steps a) above is presented in table 16 below and is calculated according to the following formula: mass of element (in g) in solid form obtained at the end of step a4) above / initial mass of element (in g) in the leaching filtrate before step a) above: [Table 16]

[0108] Steps b) and c), identical to those of example 1, are then carried out on the filtrate obtained in step a4).

Claims

Claims

1. A method for purifying a leaching filtrate from the black mass of used lithium-ion batteries and / or lithium-ion battery production scrap, said filtrate containing at least one valuable metal to be recovered, advantageously chosen from lithium, nickel, cobalt, manganese and mixtures thereof, and at least one impurity chosen from aluminum alone or in a mixture with calcium and / or fluorine, said method comprising the following steps: a) increasing, in the presence of a source of phosphates and optionally in the presence of an oxidation-reduction compound, the pH of the leaching filtrate from the black mass of used lithium-ion batteries and / or lithium-ion battery production scrap, advantageously to a pH of between 2 and 5, in particular between 3 and 4, said leaching filtrate containing at least one valuable metal, advantageously chosen from lithium, nickel, cobalt, manganese and their mixtures, and at least one impurity chosen from aluminum alone or in a mixture with calcium and / or fluorine; b) addition of a source of fluorides.

2. Method according to claim 1, characterized in that the source of phosphates is chosen from sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, lithium phosphate, ammonium phosphate, potassium phosphate, potassium dihydrogen phosphate, potassium hydrogen phosphate, tricalcium phosphate, monocalcium phosphate, dicalcium phosphate, dicalcium diphosphate, phosphoric acid and mixtures thereof, advantageously it is lithium phosphate.

3. A method according to any one of claims 1 or 2, characterized in that the leaching filtrate comprises aluminum or aluminum and iron and in that the quantity in moles of phosphate source used in step a) is adjusted to correspond to a molar ratio PO4' / (Al) of between 70% and 110%.

4. Process according to any one of claims 1 to 3, characterized in that the leaching filtrate comprises iron and in that step a) takes place in the presence of an oxidation-reduction compound, advantageously hydrogen peroxide, in particular in a content necessary to maintain the oxidation-reduction potential of step a) at a value greater than 100 mV vs Ag / AgCI, advantageously between 500 mV vs Ag / AgCI and 800 mV vs Ag / AgCI, more advantageously at a value of 600 mV vs Ag / AgCI.

5. Method according to any one of claims 1 to 4, characterized in that step a) is carried out by adding a base, advantageously lime.

6. Method according to any one of claims 1 to 5, characterized in that step a) comprises the following steps: -al) addition of the phosphate source; - a2) optional addition of the redox compound, advantageously so as to maintain the redox potential at a value greater than 100 mV vs Ag / AgCI, advantageously between 500 mV vs Ag / AgCI and 800 mV vs Ag / AgCI, more advantageously at a value of 600 mV vs Ag / AgCI; - a3) increase in pH, advantageously to a value between 2 and 5, in particular between 3 and 4.

7. Process according to any one of claims 1 to 6, characterized in that the source of fluorides in step b) is chosen from HF, NaF, LiF, KF, MgF2, CaF2, NiF, CoF, MnF, and mixtures thereof, advantageously it is LiF.

8. Process according to any one of claims 1 to 7, characterized in that the liquid part of the product obtained in step a) comprises aluminum or aluminum and calcium and in that the quantity in moles of fluoride source used in step b) is adjusted to correspond to a molar value of fluorine of between 1 and 10 times, advantageously between 4 and 7 times, the quantity in moles of aluminum and / or up to twice the quantity in moles of calcium present in the liquid part obtained in step a).

9. Process according to any one of claims 1 to 8, characterized in that the liquid part of the product obtained in step a) comprises iron and in that, during step b), the oxidation-reduction potential is adjusted to a value greater than 100 mV vs Ag / AgCI, advantageously between 500 mV vs Ag / AgCI and 800 mV vs Ag / AgCI, more advantageously to a value of 600 mV vs Ag / AgCI, in particular by adding an oxidation-reduction compound, more advantageously an oxidizing compound, even more advantageously hydrogen peroxide.

10. Method according to any one of claims 1 to 9, characterized in that, during step b), the pH is adjusted to a value between 1 and 5, advantageously between 3 and 4, in particular by adding a base such as lime or soda.

11. A method according to any one of claims 1 to 12. 10, characterized in that step b) further comprises the addition of a source of iron, advantageously in a mole content corresponding to an Fe / P molar ratio of at least 100%.

12. A method according to any one of claims 1 to 12. 11, characterized in that step b) comprises the following steps: - bl) addition of the fluoride source; - b2) optional addition of iron source; - b3) adjustment of the redox potential to a value greater than 100 mV vs Ag / AgCI, advantageously between 500 mV vs Ag / AgCI and 800 mV vs Ag / AgCI, more advantageously to a value of 600 mV vs Ag / AgCI, in particular by adding an redox compound; - b4) adjustment of the pH to a value between 1 and 5, in particular between 3 and 4.

13. A method according to any one of claims 1 to 15. 12, characterized in that the temperature of steps a) and b) is between 20°C and 95°C, advantageously between 45°C and 85°C.

14. A method according to any one of claims 1 to 14. 13, characterized in that it comprises, between steps a) and b), an intermediate step a4) of liquid / solid separation, advantageously by filtration, of the product obtained in step a), and in that step b) is carried out on the liquid part resulting from step a4).

15. A method according to any one of claims 1 to 15. 14, characterized in that it comprises, prior to step a), a preliminary step alpha) of decoppering the leaching filtrate of the black mass of used lithium-ion batteries and / or lithium-ion battery production waste and in that step a) is carried out on the copper-depleted leaching filtrate obtained in step alpha), step alpha) being advantageously carried out by precipitation of the copper sulfide so as to obtain a copper-depleted filtrate.

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