Process for recovering valuable metals from used lithium-ion batteries

Abstract

Method for recovering valuable metals from used lithium-ion batteries The present invention relates to a method for recovering at least one valuable metal from used lithium-ion batteries comprising the following successive steps: a) leaching with an acid of the black mass of used lithium-ion batteries, said black mass consisting of a mixture of black masses comprising at least 50% by mass of mechanical black mass and at most 50% by mass of thermal black mass relative to the total mass of the black mass mixture, the redox potential of the leaching solution being adjusted to a value between -100 mV vs Ag / AgCl and 700 mV vs Ag / AgCl; b) liquid / solid separation so as to obtain a solution charged with at least one valuable metal.

Description

Title of the invention: Method for recovering valuable metals from used lithium-ion batteries Technical field

[0001] The present invention relates to the general field of recycling used lithium-ion batteries 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 leaching of the black mass of used lithium-ion batteries in order to recover the valuable metal(s) from them. Prior art

[0003] When recycling used lithium-ion batteries, after separation of 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". It is generally known to dissolve the black mass in sulfuric acid in the presence of an oxidation-reduction compound in order to maximize the dissolution efficiency to values ​​close to 100%. Indeed, the acid alone is not sufficient and it is necessary to add an oxidation-reduction compound in order to maintain the oxidation-reduction potential at a value between -100 mV vs Ag / AgCl and 600 mV vs Ag / AgCl and thus promote the dissolution of certain valuable metals such as nickel or cobalt.Thus, the addition of an oxidation-reduction compound makes it possible to transform metals that are difficult to leach, either by oxidizing them or by chemically reducing them, and therefore to promote their dissolution. However, the use of such oxidation-reduction compounds is expensive and it would be interesting to be able to reduce their quantity or even not need to use them while maintaining such yields, that is to say while maintaining an oxidation-reduction potential between -100 mV vs Ag / AgCl and 700 mV vs Ag / AgCl.

[0004] The inventors discovered that by mixing two different types of black mass, obtained by different processes, it was possible to avoid the use of an oxidation-reduction compound or at least to reduce its quantity while maintaining the oxidation-reduction potential in the desired value range. Indeed, the inventors realized that these different types of black mass have different oxidation-reduction properties, which makes it possible, by mixing them, to find the right oxidation-reduction potential which will be usable during their leaching. Statement of the invention

[0005] The present invention therefore relates to a method for recovering at least one metal of value from used lithium-ion batteries comprising the following successive steps: a) leaching using an acid of the black mass of used lithium-ion batteries, said black mass consisting of a mixture of black masses comprising at least 50% by mass of mechanical black mass and at most 50% by mass of thermal black mass relative to the total mass of the black mass mixture, advantageously consisting of a mixture comprising between 50 and 95% by mass of mechanical black mass and between 5 and 50% by mass of thermal black mass, relative to the total mass of the black mass mixture, the oxidation-reduction potential of the leaching solution being maintained at a value between -100 mV vs Ag / AgCl and 700 mV vs Ag / AgCl, advantageously between -100 mV vs Ag / AgCl and 600 mV vs Ag / AgCl, even more advantageously less than 600 mV vs Ag / AgCl and b) liquid / solid separation so as to obtain a solution loaded with at least one valuable metal.

[0006] In the present application, the expressions "between ... and ...", "from ... to ..." and "in the range .......", must be understood to include limits unless explicitly stated otherwise.

[0007] Advantageously, the at least one valuable metal is nickel and / or lithium and / or cobalt and / or manganese, more advantageously it is a mixture of nickel, cobalt, manganese and lithium, even more advantageously it is nickel, alone or in a mixture with cobalt, manganese and / or lithium.

[0008] 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 / treatment of parts containing electrodes such as battery cells, from used lithium-ion batteries. This powdery fraction is suitable for recovery by hydrometallurgy. Typically, the black mass is obtained by sieving to 500 μm or less.

[0009] There are two main processing routes used for the production of black mass: - heat treatment processes at temperatures > 400 °C. A black mass called "thermal black mass" or "thermal black mass" is obtained. The thermal black mass exhibits reducing behavior, with generally an oxidation-reduction potential of -300 mV vs Ag / AgCl; - high-intensity mechanical processing processes, such as high-energy grinding. A black mass called "mechanical black mass" or "mechanical black mass" is obtained. The mechanical black mass exhibits oxidizing behavior, with a general redox potential in the range of +1000 mV to +1200 mV vs Ag / AgCl.

[0010] The black mass contains numerous valuable metals such as lithium, nickel, manganese and / or cobalt and numerous impurities such as aluminum, calcium, iron, fluorine, phosphorus and / or copper. It may also contain magnesium. It further contains graphite. Thus advantageously the black mass contains, in addition to the at least one valuable metal, graphite and impurities, in particular chosen from aluminum, calcium, iron, fluorine, phosphorus, copper, magnesium and mixtures thereof.

[0011] The black mass contains little or no polymeric materials since the latter have been eliminated upstream of the process for manufacturing the black mass.

[0012] The typical composition of a black mass (thermal or mechanical) apart from the carbon content is indicated in Table 2 of Example 1.

[0013] The method according to the invention therefore comprises at least two successive steps a) and b).

[0014] Thus, step a) of the method according to the invention consists of leaching using an acid the black mass of used lithium-ion batteries, said black mass consisting of a mixture of black masses comprising at least 50% by mass of mechanical black mass and at most 50% by mass of thermal black mass relative to the total mass of the black mass mixture, advantageously consisting of a mixture comprising between 50 and 95% by mass of mechanical black mass and between 5 and 50% by mass of thermal black mass, relative to the total mass of the black mass mixture, the oxidation-reduction potential of the leaching solution being adjusted to a value between -100 mV vs Ag / AgCl and 700 mV vs Ag / AgCl, advantageously to a value between -100 mV vs Ag / AgCl and 600 mV vs Ag / AgCl, even more advantageously less than 600 mV vs Ag / AgCl, especially greater than 300 mV vs Ag / AgCl.Indeed, the reduction of Ni, Mn and Co oxides requires an oxidation-reduction potential of < 700mV (advantageously < 600 mV vs Ag / AgCl if we want to guarantee a better yield). However, a potential that is too low favors other reactions and does not allow the dissolution of copper. Ideally, to guarantee the most interesting yields, it is necessary to be at an oxidation-reduction potential of > 300 mV vs Ag / AgCl, even if an oxidation-reduction potential of -100 mV vs Ag / AgCl already allows interesting results to be obtained.

[0015] In an advantageous embodiment, the thermal black mass is obtained by a heat treatment process at a temperature above 400°C of used lithium-ion batteries, after removal of the polymeric materials. Advantageously, it exhibits a reducing behavior and in particular it has an oxidation-reduction potential of -300 mV vs Ag / AgCl.

[0016] In another advantageous embodiment, the mechanical black mass is obtained by a high-energy grinding process of used lithium-ion batteries after elimination mination of polymeric materials. Advantageously, it exhibits oxidizing behavior and in particular an oxidation-reduction potential in the range from +1000 mV to +1200 mV vs Ag / AgCl.

[0017] The mixture of black masses according to the invention comprises at least 50% by mass of mechanical black mass and at most 50% by mass of thermal black mass relative to the total mass of the mixture of black mass, advantageously between 50 and 97% by mass of mechanical black mass and between 3 and 50% by mass of thermal black mass, more advantageously between 50 and 95% by mass of mechanical black mass and between 5 and 50% by mass of thermal black mass, even more advantageously between 50 and 90% by mass of mechanical black mass and between 10 and 50% by mass of thermal black mass, in particular between 50 and 85% by mass of mechanical black mass and between 15 and 50% by mass of thermal black mass, more particularly between 50 and 80% by mass of mechanical black mass and between 20 and 50% by mass of thermal black mass, even more particularly between 50 and 75% by mass of mass mechanical black and between 25 and 50% by mass of thermal black mass,for example 70% by mass of mechanical black mass and 30% by mass of thermal black mass or 50% by mass of mechanical black mass and 50% by mass of thermal black mass.

[0018] The acid that can be used in step a) of the process according to the invention can be any acid well known to those skilled in the art capable of leaching the black mass to dissolve the valuable metal(s) therein. It can thus be sulfuric acid H2SO4.

[0019] Advantageously, the quantity in moles of acid used is calculated to correspond to a molar ratio H+ / (Li+Co+Ni+Mn) necessary for the dissolution of lithium, cobalt, manganese and / or nickel, in particular nickel, present in the black mass, in particular between 90 and 150%, preferably between 110 and 130%, more particularly 120%.

[0020] In particular, the pH of the liquid obtained at the end of step a) is between 0 and 2.5, advantageously it is 1.5.

[0021] In an advantageous embodiment, the temperature of step a) is between 20°C and 100°C, advantageously between 50°C and 100°C, more advantageously between 70°C and 95°C, in particular it is 90°C.

[0022] In an advantageous embodiment, the duration of step a) is at most 12 hours, advantageously at most 8 hours, more advantageously between 3 hours and 5 hours, in particular it is 4 hours.

[0023] In a particularly advantageous embodiment, step a) of the method according to the invention is carried out without adding an oxidation-reduction compound, the black mass mixture according to the invention allowing the oxidation-reduction potential of the leaching solution to be maintained at a value between -100 mV vs Ag / AgCl and 700 mV vs Ag / AgCl, more advantageously at a value between -100 mV vs Ag / AgCl and 600 mV vs Ag / AgCl, even more advantageously lower than 600 mV vs Ag / AgCl, in particular higher than 300 mV vs Ag / AgCl.

[0024] In another particularly advantageous embodiment, step a) of the method according to the invention is carried out by adding an oxidation-reduction compound, advantageously chosen from those known to those skilled in the art such as hydrogen peroxide H2 O2, SO2 in gas form and their mixtures, in particular, it is H2O2. Advantageously, the content of oxidation-reduction compound used is that necessary to adjust the oxidation-reduction potential in a range between -100 mV vs Ag / AgCl and 700 mV vs Ag / AgCl, more advantageously to a value between -100 mV vs Ag / AgCl and 600 mV vs Ag / AgCl, even more advantageously less than 600 mV vs Ag / AgCl, in particular > 300 mV vs Ag / AgCl.

[0025] In an advantageous embodiment, the acid is added before the redox compound. In particular, the acid is added to a first reactor and the redox compound to a second reactor.

[0026] The method according to the present invention further comprises a step b) of liquid / solid separation of the product obtained in step a) so as to obtain a solution loaded with at least one valuable metal. This 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, in particular under pressure.

[0027] The mass yield of leaching of nickel and / or lithium and / or cobalt and / or manganese, in particular nickel, (calculated according to the following formula: 1 - mass of the element (in g) in solid form obtained at the end of step b / initial mass of element (in g) in the filtrate before step a) is advantageously greater than 80%, more advantageously greater than 90%, even more advantageously greater than 95%, in particular greater than 99%.

[0028] The solution loaded with at least one valuable metal obtained at the end of step b), also called “leaching filtrate of the black mass according to the invention”, or more simply “leaching filtrate” in the rest 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), cobalt (Co) and manganese (Mn), even more advantageously it is nickel, alone or in a mixture with lithium, cobalt and / or manganese. The nickel, cobalt, manganese and / or lithium contents of this filtrate depend on the contents present in the black masses.

[0029] The lithium content of the leaching filtrate according to the invention, if lithium is present, can thus be < 15 g / l, more advantageously between 5 g / l and 14 g / l, in particular between 9 g / l and 11 g / l.

[0030] The nickel content of the leaching filtrate according to the invention, if nickel is present, can thus be in the range 10-60 gd, more advantageously between 30 g / l and 55 g / l, in particular between 44 g / l and 48 g / l.

[0031] The cobalt content of the leaching filtrate according to the invention, if cobalt is present, can thus be in the range 1-40 gd, more advantageously between 5 gd and 20 gd, in particular between 12 gd and 15 gd.

[0032] The manganese content of the leaching filtrate according to the invention, if manganese is present, can thus be < 50 gd, more advantageously between 5 gd and 30 gd, in particular between 12 gd and 15 gd.

[0033] The leaching filtrate according to the invention contains at least one impurity. It may thus be aluminum (Al), calcium (Ca), iron (Fe), fluorine (F), phosphorus (P) and / or copper (Cu). Advantageously, it is a mixture of these impurities. The contents of aluminum (Al), calcium (Ca), iron (Fe), fluorine (F), phosphorus (P) and / or copper (Cu) in the leaching filtrate depend on the contents present in the black masses.

[0034] The aluminium content of the leaching filtrate according to the invention, if aluminium is present, can thus be < 20 g / l, more advantageously between 1 g / l and 10 g / l, in particular between 2 g / l and 4 g / l.

[0035] The calcium content of the leaching filtrate according to the invention, if calcium is present, can thus be < 0.7 g / l, more advantageously between 0.2 g / l and 0.6 gd, in particular between 0.3 g / l and 0.5 gd.

[0036] 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.

[0037] 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.

[0038] The phosphorus content in the form of PO43 of the leaching filtrate according to the invention, if phosphorus is present, can thus be < 10 gd, more advantageously between 0.1 g / l and 5 g / l, in particular between 0.5 g / l and 4 g / l.

[0039] 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 1 g / l.

[0040] The leaching filtrate according to the invention may contain other impurities such as magnesium (Mg). Typically the magnesium content, if present, of the leaching filtrate according to the invention is < 5 g / l, more advantageously between 3 gd and 4 g / l.

[0041] Advantageously, the leaching filtrate according to the invention has a pH of between 0 and 2.5, advantageously between 0.5 and 1.5. More advantageously, it is 1.

[0042] Advantageously, the leaching filtrate according to the invention has a potential redox between -100 mV vs Ag / AgCl and 700 mV vs Ag / AgCl, more advantageously between -100 mV vs Ag / AgCl and 600 mV vs Ag / AgCl, even more advantageously less than 600 mV vs Ag / AgCl, in particular greater than 300 mV vs Ag / AgCl.

[0043] The valuable metal or metals present in the leaching filtrate according to the invention may be recovered from the filtrate by methods well known to those skilled in the art, in particular by purification of the filtrate in order to remove impurities therefrom (for example by selective precipitation of the impurities followed by liquid / solid separation and then by solvent extraction), then by separation of the valuable metals.

[0044] The present invention will be better understood on 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.

[0045] EXAMPLE

[0046] Example 1: implementation of steps a) and b) of the process according to the invention without adding an oxidizing-reducing compound.

[0047] The leaching of the black mass mixture is carried out by H2SO4 at 95% at 90°C for 4 hours. The black mass mixture (100g) is dissolved in water (500g). The whole is brought to temperature and then the acid is added. The quantity of acid added is calculated to correspond to a molar ratio H+ / (Li+Co+Ni+Mn) of 120%. The tests last 4 hours, and the test conditions are presented in Table 2. The product obtained is filtered under vacuum.

[0048] The mechanical black mass has an oxidation-reduction potential (ORP) before its leaching of +1100 mV vs Ag / AgCl.

[0049] The thermal black mass has an oxidation-reduction potential (ORP) before its leaching of -300 mV vs Ag / AgCl.

[0050] The typical composition of the mechanical or thermal black mass in valuable metal and impurity (apart from carbon) is gathered in the following table 1:

[0051] [Tables 1] Elements % by mass Li 2-6 Ni 10-30 Co 3-9 Mn 3-9 Al 1-3 Ca 0-2 Mg 0-2 Cu 2-6 Fe 0-3 F 1-8 PO43 0-2

[0052] Different mixtures of black mass were produced (Ex la to le) and were compared to tests with only the mechanical black mass (Ex comp 1) or only the thermal black mass (Ex comp 2). The results are gathered in Table 2 below.

[0053] [Tables2] Quantity of mechanical black mass (g) Quantity of thermal black mass (g) Quantity of H2SO4 at 95% (g) Initial ORP (mV vs. Ag / AgCl ) Final ORP at 4h (mV vs. Ag / AgCl ) Final pH Nickel mass yield (%) Ex la 95 5 85 1100 960 1-2 86 Ex 1b 85 15 90 1100 850 1-2 93 Ex le 70 30 100 1100 650-700 1-2 96 Ex comp 1 100 0 100 1100 980 1-2 65 Ex comp 2 0 100 100 -300 -300 1-2 80

[0054] The mass yield of nickel leaching is calculated according to the following formula: 1 - mass of nickel (in g) in solid form obtained at the end of step b) / mass in nickel (in g) initial in the filtrate before step a)

[0055] Thus, the gradual addition of thermal black mass makes it possible to improve the leaching efficiency of valuable elements, in particular nickel. An advantageous way of operating corresponds to the use of a 50 / 50 mixture of thermal and mechanical black mass. It is notable that the use of black mass in a mixture makes it possible to systematically achieve better leaching efficiencies than the black masses taken separately.

[0056] A leaching filtrate is thus obtained having the composition indicated in the following table 3:

[0057] [Tables3] Elements g / 1 Li 6-12 Ni 25-35 Co 4-10 Mn 4-10 Al 1-3 Ca 0.4-0.7 Mg 0-1 Cu 2-6 Fe 0-1.5 F 0-4 PO43 0-2 Example 2: implementation of steps a) and b) of the process according to the invention with addition of redox compound.

[0058] The leaching of the black mass mixture is carried out by H2SO4 at 95% at 90°C for 4 hours. The black mass mixture (50g) is dissolved in water (328g), the whole is brought to temperature and then the acid is added. The quantity of acid added is calculated to correspond to a molar ratio H+ / (Li+Co+Ni+Mn) of 120%. The tests last 4 hours in total. 2 hours after the addition of acid, hydrogen peroxide is added with the aim of lowering the redox potential below 600 mV. If necessary, the addition of H2O2 is constant to maintain the potential below the value of 600 mV during the last 2 hours of reaction. The test conditions are presented in Table 4. The product obtained is filtered under vacuum.

[0059] The mechanical and thermal black masses are the same as those of example 1.

[0060] Different mixtures of black mass were made (Ex 2a to 2c) and were compared to tests with only the mechanical black mass (Ex comp 3) or only the thermal black mass (Ex comp 4). The results are gathered in table 4 below.

[0061] [Tables4] Quantity of mechanical black mass (g) Quantity of thermal black mass (g) Quantity of H2SO4 at 95% (g) Initial ORP (mV vs. Ag / AgCl ) Addition of H2O2 at 35% (g) Final ORP after addition of H 2O2 (mV vs. Ag / AgCl) Nickel mass yield (%) Ex 2a 47.5 2.5 57 1100 57.3 679 99.5 Ex 2b 42.5 7.5 15 1100 15.4 612 99.8 Ex 2c 35 15 13 1100 12.5 515 99.8 Ex comp 3 50 0 50 1100 60 650 99.7 Ex comp 4 0 50 50 -300 35 250 99.7

[0062] The mass yield of nickel leaching is calculated according to the following formula: 1 - mass of nickel (in g) in solid form obtained at the end of step b) / initial mass of nickel (in g) in the filtrate before step a)

[0063] The combination of the addition of a fraction of thermal black mass and the quantity of suitable reducer makes it possible to maintain leaching mass yield results greater than 99%. Increasing the mass of thermal black mass added makes it possible to reduce the quantity of hydrogen peroxide required while maintaining the same quality of results.

[0064] A leaching filtrate is thus obtained having the composition indicated in the following table 5:

[0065] [Tables5] Elements g / 1 Li 6-12 Ni 25-35 Co 4-10 Mn 4-10 Al 1-3 Ca 0.4-0.7 Mg 0-1 Cu 2-6 Fe 0-1.5 F 0-4 PO43 0-2

Claims

Claims

1. A method for recovering at least one valuable metal from used lithium-ion batteries comprising the following successive steps: a) leaching using an acid of the black mass of used lithium-ion batteries, said black mass consisting of a mixture of black masses comprising at least 50% by mass of mechanical black mass and at most 50% by mass of thermal black mass relative to the total mass of the black mass mixture, advantageously consisting of a mixture comprising between 50 and 95% by mass of mechanical black mass and between 5 and 50% by mass of thermal black mass, relative to the total mass of the black mass mixture, the oxidation-reduction potential of the leaching solution being adjusted to a value between -100 mV vs Ag / AgCl and 700 mV vs Ag / AgCl; b) liquid / solid separation so as to obtain a solution loaded with at least one valuable metal.

2. Method according to claim 1, characterized in that the thermal black mass is obtained by a heat treatment process at a temperature above 400°C of used lithium-ion batteries, after removal of the polymeric materials.

3. A method according to any one of claims 1 or 2, characterized in that the mechanical black mass is obtained by a high-energy grinding process of used lithium-ion batteries after removal of the polymeric materials.

4. Process according to any one of claims 1 to 3, characterized in that the acid of step a) is sulfuric acid.

5. Method according to any one of claims 1 to 4, characterized in that the maintenance of the redox potential of the leaching solution is carried out by adding an redox compound, advantageously chosen from hydrogen peroxide H2O2, SO2 in gas form and their mixtures.

6. Process according to any one of claims 1 to 5, characterized in that the temperature of step a) is between 20°C and 100°C, advantageously between 50°C and 100°C, more advantageously between 70°C and 95°C, in particular it is 90°C.

7. Method according to any one of claims 1 to 6, characterized in that the pH of the liquid obtained at the end of step a) is between 0 and 2, advantageously it is 1.

5.

8. Method according to any one of claims 1 to 7, characterized in that the at least one valuable metal is nickel and / or lithium and / or cobalt and / or manganese, advantageously it is a mixture of nickel, cobalt, manganese and lithium.

9. Method according to any one of claims 1 to 8, characterized in that the black mass contains, in addition to the at least one valuable metal, graphite and impurities, in particular chosen from aluminum, calcium, iron, fluorine, phosphorus, copper, magnesium and mixtures thereof.