Method for recovering battery-grade lithium carbonate from waste lithium battery positive electrode materials

Abstract

The present application relates to a method for recovering battery-grade lithium (Li) carbonate from waste Li battery positive electrode materials. The method comprises the following steps: adding water to waste Li battery positive electrode materials to obtain a slurry, and then carrying out high-pressure acid leaching; carrying out solid-liquid separation on the slurry having undergone high-pressure acid leaching to obtain a Li-rich solution and leaching residues; mixing a first precipitant and the Li-rich solution, and then carrying out impurity removal and solid-liquid separation to obtain a Li purification solution and impurity removal residues; and mixing a second precipitant and the Li purification solution, carrying out precipitation and solid-liquid separation, and then washing and drying precipitates to obtain the battery-grade Li carbonate. The method provided by the present application can achieve selective leaching of Li in the waste Li battery positive electrode materials without any oxidizing and reducing agents, the recovery rate of Li is high, and the selectivity is high; the impurity content of the leached Li-rich solution is low, a high-purity Li purification solution can be obtained by means of one-step impurity removal, no additional extraction operation is needed, and the battery-grade Li carbonate can be directly synthesized.

Description

Method for recovering battery-grade lithium carbonate from positive electrode material of waste lithium battery TECHNICAL FIELD

[0001] The present application belongs to the technical field of hydrometallurgy, and relates to a method for recycling waste lithium batteries, in particular to a method for recovering battery-grade lithium carbonate from positive electrode material of waste lithium batteries. BACKGROUND

[0002] The method for processing positive electrode material of waste lithium ion batteries in the related art includes full immersion method and selective leaching method.

[0003] The full immersion method leaches all lithium, nickel, cobalt and manganese in the positive electrode material by adding a reducing agent and an acid, and then separates the elements in the solution, which has a long process and high cost. The selective leaching method generally extracts lithium from the slag after roasting and leaching, and then recovers cobalt, nickel and manganese elements in the slag. The high-temperature roasting has high energy consumption, and there are problems of insufficient mixing and low Li recovery rate.

[0004] There are also related technical solutions that use an oxidizing agent and an additive to selectively leach, but the oxidizing agent used is expensive and has high cost. In addition, the lithium-rich solution obtained by the selective leaching method still contains many impurities, and needs to be subjected to multiple steps of impurity removal such as precipitation and extraction to obtain a high-purity lithium solution, which cannot be directly synthesized into lithium carbonate or can only obtain industrial-grade lithium carbonate. The preparation of battery-grade lithium carbonate from industrial-grade lithium carbonate also needs to be subjected to deep impurity removal treatment, which has high operation difficulty and complex process.

[0005] Therefore, there is a need to provide a method for recovering battery-grade lithium carbonate from positive electrode material of waste lithium batteries, which is simple to operate and can obtain a high-purity lithium solution.

[0006] SUMMARY

[0007] The following is a summary of the subject matter of the detailed description herein. This summary is not intended to limit the scope of the claims.

[0008] The present application provides a method for recovering battery-grade lithium carbonate from positive electrode material of waste lithium batteries, which can selectively leach Li from the positive electrode material of waste lithium batteries without any oxidizing agent and reducing agent, has high Li recovery rate and strong selectivity, and can obtain a high-purity lithium solution through one-step impurity removal without additional extraction operation, so that battery-grade lithium carbonate can be directly synthesized.

[0009] The present application provides a method for recovering battery-grade lithium carbonate from positive electrode material of waste lithium batteries, which includes the following steps:

[0010] (1) Slurry the positive electrode material of waste lithium batteries with water, and then perform pressure acid leaching;

[0011] (2) solid-liquid separation is performed on the slurry after the pressurized acid leaching to obtain a lithium-rich solution and a leaching residue;

[0012] (3) the first precipitant is mixed with the lithium-rich solution to remove impurities, solid-liquid separation is performed to obtain a lithium purified solution and a residue;

[0013] (4) the second precipitant is mixed with the lithium purified solution to perform precipitation, solid-liquid separation is performed, the precipitate is washed and dried to obtain battery-grade lithium carbonate.

[0014] The method provided in the application can realize selective leaching of Li in the positive electrode material of the waste lithium battery without any oxidant and reducing agent, and has high recovery rate and high selectivity; the lithium-rich solution obtained by leaching has low impurity content, and high-purity lithium purified solution can be obtained by one-step impurity removal without additional extraction operation, and battery-grade lithium carbonate can be directly synthesized.

[0015] In one embodiment, the liquid-solid ratio of the water slurry in step (1) is (2-5): 1, and the unit of the liquid-solid ratio is mL / g.

[0016] In one embodiment, the acid used in the pressurized acid leaching in step (1) is sulfuric acid.

[0017] In one embodiment, the amount of sulfuric acid used is 1-1.2 times the theoretical amount required for generating lithium sulfate.

[0018] In one embodiment, the temperature of the pressurized acid leaching in step (1) is 200-300°C.

[0019] In one embodiment, the time of the pressurized acid leaching in step (1) is 1-4h.

[0020] In one embodiment, the first precipitant in step (3) includes any one or a combination of at least two of sodium hydroxide, sodium sulfide or lithium hydroxide.

[0021] In one embodiment, the pH value during the impurity removal in step (3) is 9-10.

[0022] In one embodiment, the temperature of the impurity removal in step (3) is 60-100°C.

[0023] In one embodiment, the time of the impurity removal in step (3) is 0.5-2h.

[0024] In one embodiment, the second precipitant in step (4) includes sodium carbonate.

[0025] In one embodiment, the amount of the second precipitant in step (4) is 1-1.2 times the theoretical amount required for generating lithium carbonate.

[0026] In an embodiment, the temperature of the precipitation in step (4) is 80-100°C.

[0027] In an embodiment, the time of the precipitation in step (4) is 1-2h.

[0028] In an embodiment, the washing in step (4) is washing using hot water above 80°C.

[0029] The present application does not specifically limit the drying temperature and the drying time in step (4), as long as the effect of drying can be achieved.

[0030] In an embodiment, the waste lithium battery cathode material in step (1) comprises any one or a combination of at least two of lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel cobalt manganate or lithium nickel cobalt aluminum.

[0031] In an embodiment, the leaching residue obtained in step (2) and the impurity removal residue obtained in step (3) are used for recovering valuable elements.

[0032] As a preferred technical solution of the method provided by the present application, the method comprises the following steps:

[0033] (1) the waste lithium battery cathode material is slurried with water, and then subjected to pressurized acid leaching at 200-300°C for 1-4h;

[0034] The liquid-solid ratio of the water slurry is (2-5):1, and the unit of the liquid-solid ratio is mL / g;

[0035] The acid used in the pressurized acid leaching is sulfuric acid, and the amount of sulfuric acid is 1-1.2 times the theoretical requirement for generating lithium sulfate;

[0036] (2) the slurry after the pressurized acid leaching is subjected to solid-liquid separation to obtain a lithium-rich solution and a leaching residue;

[0037] (3) a first precipitant is mixed with the lithium-rich solution to remove impurities under the condition that the pH value is 9-10, and the solid-liquid separation is performed to obtain a lithium purified solution and an impurity removal residue;

[0038] The first precipitant comprises any one or a combination of at least two of sodium hydroxide, sodium sulfide or lithium hydroxide;

[0039] The temperature of the impurity removal is 60-100°C, and the time is 0.5-2h;

[0040] (4) a second precipitant is mixed with the lithium purified solution, and precipitation is performed at 80-100°C for 1-2h, and the solid-liquid separation, washing and drying of the precipitate are performed to obtain battery-grade lithium carbonate;

[0041] The second precipitant comprises sodium carbonate; and the second precipitant is used in an amount of 1-1.2 times the theoretical amount for generating lithium carbonate.

[0042] The washing is performed using hot water at 80°C or higher.

[0043] Compared with the related art, the present application has the following beneficial effects:

[0044] The method provided by the present application can realize selective leaching of Li in the positive electrode material of the waste lithium battery without any oxidant and reducing agent, and has high Li recovery rate and high selectivity; the impurity content of the lithium-rich solution obtained by leaching is low, and high-purity lithium purified solution can be obtained by one-step impurity removal without additional extraction operation, and battery-grade lithium carbonate can be directly synthesized.

[0045] Other aspects can be appreciated upon reading and understanding the attached figures and detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0046] The accompanying drawings are included to provide a further understanding of the technical solutions of the present application, and constitute a part of the specification, and are used together with the embodiments of the present application to explain the technical solutions of the present application, and do not constitute a limitation on the technical solutions of the present application.

[0047] FIG. 1 is a process flow diagram of a method for recovering battery-grade lithium carbonate from a positive electrode material of a waste lithium battery provided by Embodiment 1 of the present application. DETAILED DESCRIPTION

[0048] The technical solutions of the present application will be further described by specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application, and should not be regarded as a specific limitation on the present application.

[0049] An embodiment of the present application provides a method for recovering battery-grade lithium carbonate from a positive electrode material of a waste lithium battery, which comprises the following steps:

[0050] (1) The positive electrode material of the waste lithium battery is slurried by adding water, and then pressure acid leaching is performed;

[0051] (2) The slurry after pressure acid leaching is subjected to solid-liquid separation to obtain a lithium-rich solution and a leaching residue;

[0052] (3) A first precipitant is mixed with the lithium-rich solution to remove impurities, and solid-liquid separation is performed to obtain a lithium purified solution and a residue after impurity removal;

[0053] (4) A second precipitant is mixed with the lithium purified solution to perform precipitation, solid-liquid separation, washing, and drying of the precipitate to obtain battery-grade lithium carbonate.

[0054] The method provided by the application can realize selective leaching of Li in the positive electrode material of the waste lithium battery without any oxidant and reducing agent, and has high Li recovery rate and high selectivity; the impurity content of the lithium-rich solution obtained by leaching is low, and high-purity lithium purified solution can be obtained by one-step impurity removal without additional extraction operation, and battery-grade lithium carbonate can be directly synthesized.

[0055] In some embodiments, the liquid-to-solid ratio of the water slurry in step (1) is (2-5):1, for example, it can be 2:1, 3:1, 4:1 or 5:1, and the unit of the liquid-to-solid ratio is mL / g.

[0056] If the liquid-to-solid ratio in step (1) is too low, the slurry will be too thick, which is not conducive to stirring and mixing; if the liquid-to-solid ratio is too high, the Li concentration in the slurry obtained by pressure acid leaching will be too low, which is not conducive to subsequent operations.

[0057] In some embodiments, the acid used in the pressure acid leaching in step (1) is sulfuric acid.

[0058] For example, the sulfuric acid is concentrated sulfuric acid, and the concentration of the concentrated sulfuric acid is ≥90wt%, for example, it can be 90wt%, 92wt%, 94wt%, 95wt%, 96wt% or 98wt%, but is not limited to the listed values, and other unlisted values within the value range are also applicable.

[0059] In some embodiments, the amount of sulfuric acid used is 1-1.2 times the theoretical amount required to generate lithium sulfate, for example, it can be 1 times, 1.05 times, 1.1 times, 1.15 times or 1.2 times, but is not limited to the listed values, and other unlisted values within the value range are also applicable.

[0060] The application controls the amount of sulfuric acid to be 1-1.2 times the theoretical amount required to generate lithium sulfate, which avoids the increase in impurity content caused by excessive acid, and avoids the loss of Li caused by impurity entrainment.

[0061] In some embodiments, the temperature of the pressure acid leaching in step (1) is 200-300℃, for example, it can be 200℃, 220℃, 250℃, 270℃, 280℃ or 300℃, but is not limited to the listed values, and other unlisted values within the value range are also applicable.

[0062] The pressure acid leaching in step (1) is carried out in a closed container, and the pressure of the pressure acid leaching changes with temperature, which is not specifically limited in the application, as long as the temperature of the pressure acid leaching is 200-300℃; if the temperature of the pressure acid leaching is too low, it is not conducive to the leaching of Li, and the impurity content will relatively increase; if the temperature of the pressure acid leaching is too high, the requirement for equipment is higher, which increases unnecessary cost.

[0063] In certain embodiments, the time for the pressure acid leaching in step (1) is 1-4 h, for example, it can be 1 h, 2 h, 3 h or 4 h, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0064] In certain embodiments, the first precipitant in step (3) comprises any one or a combination of at least two of sodium hydroxide, sodium sulfide or lithium hydroxide, typically but not limitedly, the combination comprises sodium hydroxide and sodium sulfide, sodium sulfide and lithium hydroxide, sodium hydroxide and lithium hydroxide, or sodium hydroxide, sodium sulfide and lithium hydroxide.

[0065] In certain embodiments, the pH value in the impurity removal in step (3) is 9-10, for example, it can be 9, 9.5 or 10, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0066] In certain embodiments, the temperature in the impurity removal in step (3) is 60-100℃, for example, it can be 60℃, 70℃, 80℃, 90℃ or 100℃, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0067] In certain embodiments, the time for the impurity removal in step (3) is 0.5-2 h, for example, it can be 0.5 h, 1 h, 1.5 h or 2 h, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0068] In certain embodiments, the second precipitant in step (4) comprises sodium carbonate.

[0069] In certain embodiments, the amount of the second precipitant in step (4) is 1-1.2 times the theoretical amount for generating lithium carbonate, for example, it can be 1 times, 1.05 times, 1.1 times, 1.15 times or 1.2 times, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0070] The application controls the amount of the second precipitant to be 1-1.2 times the theoretical amount for generating lithium carbonate, which avoids the excessive amount of the second precipitant causing the impurity Na to exceed the standard.

[0071] In certain embodiments, the temperature in the precipitation in step (4) is 80-100℃, for example, it can be 80℃, 85℃, 90℃, 95℃ or 100℃, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0072] In some embodiments, the time for the precipitation in step (4) is 1-2 h, for example, it can be 1 h, 1.2 h, 1.5 h, 1.8 h or 2 h, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0073] In some embodiments, the washing in step (4) is performed using hot water at a temperature of 80°C or higher, for example, it can be 80°C, 82°C, 85°C, 88°C or 90°C, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0074] The solubility of lithium carbonate decreases with increasing temperature, and the use of hot water at a temperature of 80°C or higher in the present application can reduce the loss of Li during the washing process.

[0075] The present application does not specifically limit the drying temperature and drying time in step (4), as long as the effect of drying can be achieved.

[0076] In some embodiments, the waste lithium battery cathode material in step (1) comprises any one or a combination of at least two of lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel cobalt manganate or lithium nickel cobalt aluminumate. Typical but non-limiting combinations include a combination of lithium cobaltate and lithium manganate, a combination of lithium nickelate and lithium nickel cobalt manganate, a combination of lithium nickel cobalt manganate and lithium nickel cobalt aluminumate, a combination of lithium cobaltate, lithium manganate and lithium nickelate, or a combination of lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel cobalt manganate and lithium nickel cobalt aluminumate.

[0077] In some embodiments, the leaching residue obtained in step (2) and the impurity removal residue obtained in step (3) are used to recover valuable elements.

[0078] For example, when the waste lithium battery cathode material is lithium cobaltate, the leaching residue obtained in step (2) and the impurity removal residue obtained in step (3) are used to recover cobalt; when the waste lithium battery cathode material is lithium manganate, the leaching residue obtained in step (2) and the impurity removal residue obtained in step (3) are used to recover manganese; when the waste lithium battery cathode material is lithium nickelate, the leaching residue obtained in step (2) and the impurity removal residue obtained in step (3) are used to recover nickel; when the waste lithium battery cathode material is lithium nickel cobalt manganate, the leaching residue obtained in step (2) and the impurity removal residue obtained in step (3) are used to recover nickel, cobalt and manganese; when the waste lithium battery cathode material is lithium nickel cobalt aluminumate, the leaching residue obtained in step (2) and the impurity removal residue obtained in step (3) are used to recover nickel, cobalt and aluminum.

[0079] The method provided in some embodiments of the present application comprises the following steps:

[0080] (1) The waste lithium battery cathode material is slurried with water, and then subjected to pressure acid leaching at 200-300°C for 1-4 h;

[0081] The liquid-solid ratio of the slurry is (2-5):1, and the unit of the liquid-solid ratio is mL / g;

[0082] The acid used in the pressure acid leaching is sulfuric acid, and the amount of sulfuric acid is 1-1.2 times the theoretical amount required for generating lithium sulfate;

[0083] (2) The slurry after the pressure acid leaching is subjected to solid-liquid separation to obtain a lithium-rich solution and a leaching residue;

[0084] (3) The first precipitant is mixed with the lithium-rich solution, and impurities are removed under the condition that the pH value is 9-10, and the solid-liquid separation is performed to obtain a lithium purification liquid and a residue after impurity removal;

[0085] The first precipitant includes any one or a combination of at least two of sodium hydroxide, sodium sulfide, or lithium hydroxide;

[0086] The temperature of the impurity removal is 60-100℃, and the time is 0.5-2h;

[0087] (4) The second precipitant is mixed with the lithium purification liquid, and the precipitation is performed at 80-100℃ for 1-2h, and the solid-liquid separation is performed, the precipitate is washed and dried to obtain a battery-grade lithium carbonate;

[0088] The second precipitant includes sodium carbonate, and the amount of the second precipitant is 1-1.2 times the theoretical amount required for generating lithium carbonate;

[0089] The washing is performed using hot water above 80℃.

[0090] In order to clearly illustrate the technical solutions of the present application, the waste lithium battery cathode material treated in the following examples is a nickel-cobalt-manganese lithium ternary cathode material. The main components of the waste lithium battery cathode material powder are 6.8wt% of Co, 18wt% of Ni, 14wt% of Mn, 4.4wt% of Li, 1.37wt% of Cu, 0.89wt% of Fe, and 0.94wt% of Al. This limitation is only for the purpose of clearly illustrating the technical solutions of the present application, and is not considered as a further limitation of the present application.

[0091] Example 1

[0092] The present embodiment provides a method for recovering battery-grade lithium carbonate from a waste lithium battery cathode material as shown in FIG. 1, which comprises the following steps:

[0093] (1) The waste lithium battery cathode material is slurried with water, and then subjected to pressure acid leaching at 250℃ for 2h;

[0094] The liquid-solid ratio of the slurry is 3:1, and the unit of the liquid-solid ratio is mL / g;

[0095] The acid used in the pressurized acid leaching is concentrated sulfuric acid with a concentration of 98wt%, and the amount of concentrated sulfuric acid is 1.1 times the theoretical amount required to generate lithium sulfate;

[0096] (2) The slurry after the pressurized acid leaching is subjected to solid-liquid separation to obtain a lithium-rich solution and a leaching residue;

[0097] (3) The first precipitant is mixed with the lithium-rich solution, and impurities are removed under the condition that the pH value is 9.5, and then solid-liquid separation is performed to obtain a lithium purified solution and a residue after impurity removal;

[0098] The first precipitant is sodium hydroxide;

[0099] The temperature of the impurity removal is 80℃, and the time is 1h;

[0100] (4) The second precipitant is mixed with the lithium purified solution, and precipitation is performed at 90℃ for 1.5h, and then solid-liquid separation is performed, the precipitate is washed and dried to obtain battery-grade lithium carbonate;

[0101] The second precipitant is sodium carbonate, and the amount of the second precipitant is 1.1 times the theoretical amount required to generate lithium carbonate;

[0102] The washing is performed using hot water at 80℃.

[0103] Example 2

[0104] The embodiment provides a method for recovering battery-grade lithium carbonate from a positive electrode material of a waste lithium battery, and the method comprises the following steps:

[0105] (1) The positive electrode material of the waste lithium battery is slurried by adding water, and then pressurized acid leaching is performed at 200℃ for 4h;

[0106] The liquid-solid ratio of the water slurry is 2:1, and the unit of the liquid-solid ratio is mL / g;

[0107] The acid used in the pressurized acid leaching is concentrated sulfuric acid with a concentration of 98wt%, and the amount of concentrated sulfuric acid is 1 times the theoretical amount required to generate lithium sulfate;

[0108] (2) The slurry after the pressurized acid leaching is subjected to solid-liquid separation to obtain a lithium-rich solution and a leaching residue;

[0109] (3) The first precipitant is mixed with the lithium-rich solution, and impurities are removed under the condition that the pH value is 9, and then solid-liquid separation is performed to obtain a lithium purified solution and a residue after impurity removal;

[0110] The first precipitant is lithium hydroxide;

[0111] The temperature of the impurity removal is 60℃, and the time is 2h;

[0112] (4) mixing the second precipitant with the lithium purification solution, precipitating at 80°C for 2h, solid-liquid separation, washing and drying the precipitate to obtain the battery-grade lithium carbonate;

[0113] The second precipitant is sodium carbonate, and the amount of the second precipitant is 1 times the theoretical amount required for generating lithium carbonate.

[0114] The washing is washing with hot water at 80°C.

[0115] Example 3

[0116] The embodiment provides a method for recycling battery-grade lithium carbonate from a waste lithium battery cathode material, and the method comprises the following steps:

[0117] (1) slurry the waste lithium battery cathode material by adding water, and then perform pressurized acid leaching at 300°C for 1h;

[0118] The liquid-solid ratio of the slurry is 5:1, and the unit of the liquid-solid ratio is mL / g.

[0119] The acid used in the pressurized acid leaching is concentrated sulfuric acid with a concentration of 98wt%, and the amount of the concentrated sulfuric acid is 1.2 times the theoretical amount required for generating lithium sulfate.

[0120] (2) perform solid-liquid separation on the slurry after the pressurized acid leaching to obtain a lithium-rich solution and a leaching residue;

[0121] (3) mix the first precipitant with the lithium-rich solution, and perform impurity removal under the condition that the pH value is 10, perform solid-liquid separation to obtain a lithium purification solution and an impurity removal residue;

[0122] The first precipitant is sodium sulfide.

[0123] The temperature of the impurity removal is 100°C, and the time is 0.5h.

[0124] (4) mixing the second precipitant with the lithium purification solution, precipitating at 100°C for 1h, solid-liquid separation, washing and drying the precipitate to obtain the battery-grade lithium carbonate;

[0125] The second precipitant is sodium carbonate, and the amount of the second precipitant is 1.2 times the theoretical amount required for generating lithium carbonate.

[0126] The washing is washing with hot water at 80°C.

[0127] Example 4

[0128] The embodiment provides a method for recycling battery-grade lithium carbonate from a waste lithium battery cathode material, and the method comprises the following steps:

[0129] Example 5

[0130] The embodiment provides a method for recycling battery-grade lithium carbonate from waste lithium battery positive electrode materials, and the method is the same as that in the embodiment 1 except that the temperature of the pressure acid leaching is 320 DEG C.

[0131] The temperature of the pressure acid leaching in the embodiment is too high, and the pressure acid leaching equipment cannot perform the pressure acid leaching under the temperature condition, so the method provided in the embodiment cannot be smoothly performed.

[0132] Embodiment 6

[0133] The embodiment provides a method for recycling battery-grade lithium carbonate from waste lithium battery positive electrode materials, and the method is the same as that in the embodiment 1 except that the liquid-solid ratio of the water slurry is 1:1.

[0134] The water amount is too small during the water slurry in the embodiment, so that the slurry after the slurry is too thick and cannot be used for subsequent operation, so the method provided in the embodiment cannot be smoothly performed.

[0135] Embodiment 7

[0136] The embodiment provides a method for recycling battery-grade lithium carbonate from waste lithium battery positive electrode materials, and the method is the same as that in the embodiment 1 except that the liquid-solid ratio of the water slurry is 6:1.

[0137] Embodiment 8

[0138] The embodiment provides a method for recycling battery-grade lithium carbonate from waste lithium battery positive electrode materials, and the method is the same as that in the embodiment 1 except that the amount of the sulfuric acid is 1.3 times of the theoretical demand of lithium sulfate.

[0139] Embodiment 9

[0140] The embodiment provides a method for recycling battery-grade lithium carbonate from waste lithium battery positive electrode materials, and the method is the same as that in the embodiment 1 except that the impurity removal in the step (3) is performed under the condition that the pH value is 8.5.

[0141] Embodiment 10

[0142] The embodiment provides a method for recycling battery-grade lithium carbonate from waste lithium battery positive electrode materials, and the method is the same as that in the embodiment 1 except that the impurity removal in the step (3) is performed under the condition that the pH value is 10.5.

[0143] Embodiment 11

[0144] The embodiment provides a method for recycling battery-grade lithium carbonate from waste lithium battery positive electrode materials, and the method is the same as that in the embodiment 1 except that the temperature of the impurity removal in the step (3) is 50 DEG C.

[0145] Embodiment 12

[0146] The embodiment provides a method for recycling battery-grade lithium carbonate from waste lithium battery positive electrode material, and the method is the same as that in the embodiment 1, except that the temperature of the precipitation in the step (4) is 70 DEG C.

[0147] Embodiment 13

[0148] The embodiment provides a method for recycling battery-grade lithium carbonate from waste lithium battery positive electrode material, and the method is the same as that in the embodiment 1, except that the amount of the sodium carbonate is 1.3 times of the theoretical amount of the lithium carbonate.

[0149] The leaching rate, direct recovery rate and purity of the obtained lithium carbonate in the above embodiments are determined, and the results are shown in Table 1.

[0150] Table 1

[0151] Since the embodiment 5 and the embodiment 6 cannot be successfully carried out, the corresponding test data in Table 1 are marked as "-".

[0152] In summary, the method provided in the application can realize the selective leaching of Li in the waste lithium battery positive electrode material without any oxidant and reducing agent, and has high recovery rate and high selectivity; the impurity content of the lithium-rich solution obtained by leaching is low, and high-purity lithium purified solution can be obtained by one-step impurity removal, without additional extraction operation, so that the battery-grade lithium carbonate can be directly synthesized.

[0153] The above merely describes specific embodiments of the application, but the protection scope of the application is not limited thereto, and those skilled in the art should understand that any changes or replacements within the technical scope disclosed in the application can be easily thought of by those skilled in the art, and all the changes or replacements fall within the protection scope and disclosure scope of the application.

Claims

1. A method for recovering battery-grade lithium carbonate from spent lithium battery cathode material, comprising the following steps: (1) slurry the spent lithium battery cathode material with water, and then perform pressure acid leaching; (2) perform solid-liquid separation on the slurry after pressure acid leaching to obtain a lithium-rich solution and a leaching residue; (3) mix a first precipitant with the lithium-rich solution, perform impurity removal, and perform solid-liquid separation to obtain a lithium purified solution and an impurity removal residue; (4) mix a second precipitant with the lithium purified solution, perform precipitation, solid-liquid separation, washing, and drying of the precipitate to obtain battery-grade lithium carbonate.

2. The method of claim 1, wherein, The liquid-solid ratio of the water slurry in step (1) is (2-5) : 1, and the unit of the liquid-solid ratio is mL / g.

3. The method of claim 1 or 2, wherein, The acid used in the pressure acid leaching in step (1) is sulfuric acid.

4. The method of claim 3, wherein, The amount of sulfuric acid used is 1-1.2 times the theoretical amount required to generate lithium sulfate.

5. The method according to any one of claims 1 to 4, wherein, The temperature of the pressure acid leaching in step (1) is 200-300℃.

6. The method according to any one of claims 1 to 5, wherein, The time of the pressure acid leaching in step (1) is 1-4h.

7. The method according to any one of claims 1-6, wherein, The first precipitant in step (3) includes any one or a combination of at least two of sodium hydroxide, sodium sulfide, or lithium hydroxide.

8. The method of any one of claims 1-7, wherein, The pH value during impurity removal in step (3) is 9-10.

9. The method of any one of claims 1-8, wherein, The temperature of impurity removal in step (3) is 60-100℃.

10. The method of any one of claims 1-9, wherein, The time of impurity removal in step (3) is 0.5-2h.

11. The method of any one of claims 1-10, wherein, The second precipitant in step (4) includes sodium carbonate.

12. The method of any one of claims 1-11, wherein, The amount of the second precipitant used in step (4) is 1-1.2 times the theoretical amount required to generate lithium carbonate.

13. The method of any one of claims 1-12, wherein, The temperature of precipitation in step (4) is 80-100℃. Optionally, the time of precipitation in step (4) is 1-2h. Optionally, the washing in step (4) is performed using hot water above 80℃.

14. The method of any one of claims 1-13, wherein, The spent lithium battery cathode material in step (1) includes any one or a combination of at least two of lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel cobalt manganate, or lithium nickel cobalt aluminumate. Optionally, the leaching residue obtained in step (2) and the impurity removal residue obtained in step (3) are used to recover valuable elements. 15.The method of claim 1, comprising the following steps: (1) slurry the spent lithium battery cathode material with water, and then perform pressure acid leaching at 200-300℃ for 1-4h; The liquid-solid ratio of the water slurry is (2-5) : 1, and the unit of the liquid-solid ratio is mL / g. The acid used in the pressure acid leaching is sulfuric acid, and the amount of sulfuric acid used is 1-1.2 times the theoretical amount required to generate lithium sulfate. (2) perform solid-liquid separation on the slurry after pressure acid leaching to obtain a lithium-rich solution and a leaching residue; (3) mix a first precipitant with the lithium-rich solution, perform impurity removal at a pH value of 9-10, and perform solid-liquid separation to obtain a lithium purified solution and an impurity removal residue; The first precipitant includes any one or a combination of at least two of sodium hydroxide, sodium sulfide, or lithium hydroxide. The temperature of impurity removal is 60-100℃, and the time is 0.5-2h. (4) mix a second precipitant with the lithium purified solution, perform precipitation at 80-100℃ for 1-2h, perform solid-liquid separation, washing, and drying of the precipitate to obtain battery-grade lithium carbonate; The second precipitant includes sodium carbonate, and the amount of the second precipitant used is 1-1.2 times the theoretical amount required to generate lithium carbonate. ​ The washing is performed using hot water of 80°C or higher. The washing is performed using hot water of 80°C or higher.

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