METHOD FOR REMOVING IMPURITIES FROM USED LITHIUM BATTERY LEACHATE

Abstract

A process for removing impurities from a used lithium battery leachate is disclosed, which process relates to the technical field of removing impurities by a wet process.The process for removing impurities from the used lithium battery leachate of this application includes performing a first copper removal on the used lithium battery leachate by adding a first impurity removal agent, performing a second copper removal on the first copper-free solution by adding a second impurity removal agent, adjusting the pH of the second copper-free solution by adding an alkali to precipitate iron and aluminum, and performing a deep impurity removal with sodium carbonate and sodium sulfide on the solution after the removal of iron, aluminum, and copper by adding the alkali, and using the solution after the deep impurity removal to recover nickel, cobalt, manganese, and lithium.In this process, the slag obtained from the second copper removal stage is used as the first impurity removal agent for the subsequent batch. Similarly, the slag obtained from the deep impurity removal stage is used as the first impurity removal agent for the second impurity removal stage in the following batch. Excellent impurity removal is achieved by recycling waste slag and raw materials in the preceding and subsequent processes without the introduction of any external impurity removal agents. This process reduces metallic impurities, minimizes precious metal loss, alkali addition, and slag generation, resulting in a safe and economically efficient impurity removal process.

Description

Title of the invention: METHOD FOR REMOVING IMPURITIES FROM USED LITHIUM BATTERY LEACHATE technical field

[0001] The present application relates to the technical field of the removal of impurities by a wet process, and relates specifically to a process for removing impurities from a leachate of a used lithium battery.

[0002] BACKGROUND

[0003] The active cathode material of a ternary lithium battery is an important component of a battery, containing large quantities of precious metals such as nickel, cobalt, manganese, and lithium. Recovering these precious metals from spent battery material and thus utilizing these resources will produce significant environmental and economic benefits, demonstrating its profound importance.

[0004] The recovery of precious metals from the active cathode material of spent lithium batteries generally requires pretreatment separation such as crushing, dismantling, and screening, after which the precious metals are recovered by hydrometallurgy. However, during the pretreatment separation stage, due to the limited effect of mechanical separation, some impurities such as copper, iron, and aluminum, etc., will be mixed with the black mass and carried over in a leachate during subsequent leaching treatment. In order to recycle nickel, cobalt, and manganese, it is necessary to remove copper, iron, and aluminum from the leachate. Currently, the process for removing copper from the leachate of ternary battery material mainly involves replacing the iron powder and removing the copper with sodium sulfide.However, these methods present the following problems.

[0005] For the iron powder replacement process, the amount of iron powder added is greater, with 50 to 100 kg added to the leachate for each ton of material, resulting in a 20% to 60% increase in the iron slag generated per ton of material. The increased slag will remove more precious metals such as nickel and cobalt, etc., leading to a greater loss of precious metals like nickel and cobalt, etc. Due to the presence of Fe3+ in the leachate, some of the added iron powder will react with Fe3+, so the amount of iron powder added must be increased, and the amount of iron slag will be further increased. In production practice, 10% of the powder Iron reacts with Fe3+ to produce Fe2+; furthermore, the large quantity of Fe2+ must be oxidized by the oxidizing agent to be completely removed during the iron and aluminum removal process, which increases the oxidation process and the amount of oxidizing agent used. Thus, the total operating time is extended by 20% to 40%, the downtime for the material is long, and the workload is increased. When deep impurity removal is carried out after iron and aluminum removal, the resulting slag can only be returned to the previous leaching stage for recovery, as it contains a large amount of nickel sulfide and cobalt sulfide, leading to a decrease in the amount of battery material that can be processed.Due to the presence of sodium sulfide, nickel sulfide, cobalt sulfide, and copper sulfide, the slags from deep impurity removal will consume increasing amounts of acids and oxidizing agents when returned to the previous leaching stage, thus increasing the cost.

[0006] For the copper removal process with sodium sulfide, due to the presence of sulfuric acid in the leachate, which can react with sodium sulfide to produce a highly toxic gas, hydrogen sulfide, safety is poor. The nickel and cobalt contents of the leachate are higher, and nickel and cobalt will form sulfides when the copper concentration is reduced and precipitate together with the copper, resulting in the loss of precious metals and reducing the recovery rate.

[0007] It is therefore a difficult problem for the industry to solve to establish a process for removing impurities from used lithium battery leachate, which is guaranteed to be low cost, high efficiency and safe without introducing more metallic impurities or wasting precious metals to be recovered.

[0008] SUMMARY

[0009] In view of the defects existing in the prior art, an objective of the present application is to provide a process for removing impurities from a used lithium battery leachate, by which not only do the metallic impurities not increase, but also the recovery rate of precious metals such as nickel and cobalt, etc., is high, with low cost and high safety.

[0010] In order to achieve the objective described above, this application provides a method for removing impurities from a leachate of a used lithium battery, comprising the following steps:

[0011] of carrying out a first removal of copper on a leachate from a used lithium battery by adding a first impurity removal agent, so as to obtain copper slags and a first solution free of copper;

[0012] of carrying out a second copper removal on the first copper-free solution by adding a second impurity removal agent, so as to obtain slag and a second copper-free solution, where the resulting slag is used as the first impurity removal agent for the used lithium battery leachate in the next batch to remove impurities;

[0013] adjusting the pH of the second solution freed from copper by adding an alkali to precipitate iron and aluminum, so as to obtain iron and aluminum slags and a solution after the removal of iron, aluminum and copper;

[0014] of carrying out a thorough removal of impurities from the solution after the removal of iron, aluminum, and copper by adding sodium carbonate and sodium sulfide, so as to obtain slag and a solution after the thorough removal of impurities, wherein the resulting slag is used as a second impurity-removing agent for the spent lithium battery leachate in the next batch to remove impurities; and

[0015] of use of the solution after the deep removal of impurities to recover nickel, cobalt, manganese and lithium.

[0016] Where the first impurity-removing agent comprises copper sulfide, nickel sulfide, cobalt sulfide, iron hydroxide, and aluminum hydroxide, and a total mass percentage of nickel sulfide and cobalt sulfide in the first impurity-removing agent is greater than or equal to 70%; and

[0017] The second impurity removal agent comprises copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide, a total mass percentage of nickel sulfide and cobalt sulfide in the second impurity removal agent is greater than or equal to 80%, and a total mass percentage of nickel hydroxide and cobalt hydroxide in the second impurity removal agent is between 5% and 15%.

[0018] The first impurity removal agent is mainly composed of nickel sulfide and cobalt sulfide, and without adding iron powder, most of the copper in the used lithium battery leachate can be replaced by a reaction between nickel sulfide and cobalt sulfide and copper ions and nickel sulfide and cobalt sulfide are converted into copper sulfide.

[0019] The second impurity removal agent is used to remove more copper from the leachate, so that more copper is removed from the slag (i.e., the first impurity removal agent is used for the removal of impurities in the next batch).

[0020] Sodium sulfide added during the deep removal of impurities completely removes copper, and furthermore, the generated byproducts, nickel sulfide and cobalt sulfide, are returned to the second copper removal stage, thus the nickel and cobalt are again transferred into the leachate, reducing the loss of nickel and cobalt. Meanwhile, the added sodium carbonate removes iron and aluminum at depth, and furthermore, the generated byproducts, nickel hydroxide and cobalt hydroxide, are returned to the second copper removal stage and subsequently consume the residual acid in the leachate to some extent, reducing the amount of alkali used to remove iron and aluminum, and transforming the nickel and cobalt back into the leachate, thus reducing the loss of nickel and cobalt.

[0021] In the process, the recycling and reuse of the impurity removal agent without increasing metallic impurities is achieved by recycling and reusing the second impurity removal agent generated by the deep removal of impurities during the second copper removal for deep copper removal, and by recycling and reusing the first impurity removal agent generated by the second copper removal during the first copper removal for primary copper removal. Meanwhile, the nickel and cobalt that are sulfided and transformed into slag during the deep removal of impurities are returned to the system via the two copper removal processes so as to be recovered, thus reducing the loss of precious metals.

[0022] The process described above exhibits high impurity removal efficiency, low precious metal loss, low consumption of auxiliary materials and less generation of waste slag; and the operating cycle is shortened, equipment investment is reduced, no toxic and harmful gases are produced and safety is improved.

[0023] Preferably, the wet mass of the first added impurity removal agent represents 3% to 20% of the mass of the spent lithium battery leachate. During the first copper removal, the reaction temperature is between 50 and 90°C and the reaction time is between 1 and 5 h. When the first impurity removal is carried out under such process conditions, copper can be better removed from the leachate, so that the copper content is reduced to less than 1 g / L. In addition, the less valuable metals are removed by the generated copper slag, and based on detection in the water-washed copper slag, the Cu mass / Ni mass within it is greater than 15. Optionally, the wet mass of the first removal agent Added impurities may represent 3% to 15%, or 3% to 12%, relative to the mass of the used lithium battery leachate.

[0024] Preferably, the mass on a wet basis of the first added impurity removal agent may also represent 5%, or 10%, or 13%, or 16%, or 18% relative to the mass of the used lithium battery leachate.

[0025] In this disclosure, a method for calculating the "3% to 20%" in the expression "a mass on a wet basis of the first added impurity removal agent represents 3% to 20% relative to the mass of the spent lithium battery leachate" is as follows: the value in grams of the wet basis of the first added impurity removal agent / the value in millilitres of the lithium battery leachate x 100% and the calculation methods for other similar expressions are similar.

[0026] Preferably, the wet mass of the second added impurity removal agent represents 3.5% to 40% by mass of the spent lithium battery leachate. During the second copper removal, the reaction temperature is between 50 and 90°C and the reaction time is between 1 and 5 h. When the first impurity removal is carried out under such specific process conditions, the copper can be removed more thoroughly, so that the copper content in the leachate is reduced to less than 2 mg / L. Optionally, the wet mass of the second added impurity removal agent may represent 3.5% to 30%, or 3.5% to 20%, or 3.5% to 10% by mass of the spent lithium battery leachate.Optionally, the mass on a wet basis of the second added impurity removal agent may also represent 5%, or 10%, or 13%, or 16%, or 18%, or 21%, or 25%, or 28%, or 31%, or 35%, or 38% relative to the mass of the spent lithium battery leachate.

[0027] In this disclosure, a method for calculating the "3.5% to 40%" in the expression "a mass on a wet basis of the second added impurity removal agent represents 3.5% to 40% relative to a mass of the spent lithium battery leachate" is as follows: the value in grams of the wet basis of the second added impurity removal agent / the value in millilitres of the lithium battery leachate x 100% and the calculation methods for other similar expressions are similar.

[0028] Preferably, in the process of adjusting the pH of the second solution freed of copper by adding an alkali to precipitate iron and aluminum, the pH is adjusted to 4.0–4.5 by adding the alkali, the reaction temperature is between 80 and 95°C, and the reaction time is between 1 and 5 h. By carrying out the iron and aluminum removal process under such specific conditions, the iron and Aluminium can be better removed from leachate, and a total Ni, Co and Mn content in the washed iron and aluminium slag is less than 1.5% by weight.

[0029] Preferably, in the process of adjusting the pH by adding an alkali to the second solution freed from copper in order to precipitate iron and aluminum, the alkali used is at least one of sodium carbonate and sodium hydroxide.

[0030] Preferably, in the process of adjusting the pH by adding an alkali to the second solution freed from copper in order to precipitate iron and aluminum, the alkali used is an alkaline solution, and a mass percentage of alkali in the alkaline solution is greater than or equal to 15%.

[0031] Preferably, during the deep removal of impurities, a reaction temperature is between 70 and 90°C, a reaction time is between 1 and 3 h, and the pH at an endpoint of reaction is between 6.0 and 6.5. By carrying out the deep removal of impurities under such specific process conditions, copper, iron and aluminum can be better removed from the leachate, so that the copper content in the leachate is reduced to less than 0.5 mg / L, the iron content in the leachate is reduced to less than 3 mg / L, and the aluminum content in the leachate is reduced to less than 1 mg / L.

[0032] Preferably, the used lithium battery leachate has a pH ranging from 1.0 to 2.0 and comprises components having the following contents:

[0033] Ni from 35 to 65 g / L, Co from 15 to 35 g / L, Mn from 10 to 25 g / L, Cu from 0 to 10 g / L (more than 0), Fe from 0 to 10 g / L (more than 0) and Al from 0 to 10 g / L (more than 0); the first solution freed from copper satisfies: Cu < 1 g / L, and the copper slags are washed with water and then satisfy: mass of Cu / mass of Ni > 15; the second solution freed from copper satisfies: Cu < 2 mg / L; and the solution after the thorough removal of impurities satisfies: Cu < 0.5 mg / L, Fe < 3 mg / L and Al < 1 mg / L.

[0034] Preferably, the process for removing impurities from a used lithium battery leachate also satisfies at least one of the conditions (a) and (b):

[0035] (a) during the deep removal of impurities, sodium carbonate and the Added sodium sulfide constitutes a mixed solution of sodium carbonate and sodium sulfide, and in the mixed solution of sodium carbonate and sodium sulfide, the mass percentage of sodium carbonate is between 5% and 20%, and the mass percentage of sodium sulfide is between 5% and 20%. The copper slags are washed with water and subjected to solid-liquid separation, so as to obtain washed copper slags and water after washing the copper slags; the washed copper slags are used to recover the copper, and the water after washing the copper slags is used as a solvent for the mixed solution of sodium carbonate and sodium sulfide during the deep removal of impurities; and

[0036] (b) the iron and aluminum slags are washed with water and subjected to separation solid-liquid, so as to obtain washed iron and aluminum slag and water after washing the iron and aluminum slag, and the resulting water after washing the iron and aluminum slag is added to a used lithium battery leachate in the next batch for the removal of impurities.

[0037] The water after washing generated by washing the copper slag produced during the first removal of copper with water can be used as a solvent for the mixed solution of sodium carbonate and sodium sulfide used during the deep removal of impurities, which not only reduces the amount of water used, but also reduces the generation of wastewater.

[0038] The water after washing the iron and aluminum slag contains precious metals, which can be returned to the first copper removal process in the next batch, so as to recover the precious metals in it and further reduce the loss of precious metals.

[0039] Preferably, in the case where copper slag is washed with water, a mass of the water used is 2 to 10 times the mass on a wet basis of the copper slag, which not only allows the copper slag to be cleaned effectively, but also avoids excessive use of water.

[0040] Preferably, in the case where iron and aluminum slags are washed with water, a washing process used is a three-stage counter-current washing, and a mass of the water used is 2 to 10 times the mass on a wet basis of the iron and aluminum slags, which makes it possible to effectively clean the iron and aluminum slags, but also to avoid excessive use of water.

[0041] There are no particular requirements for the initial source of the first and second impurity-removing agents, which, for example, can be prepared by adding an alkaline solution and sodium sulfide to a leachate (Cu <0.1 g / L, Fe < 0.5 g / L, and Al < 1 g / L) of lithium battery cathode foils containing a low content of copper, iron and aluminum, but not limited to these.

[0042] Compared to the prior art, the beneficial effects of the present application lie in the fact that: in the present application, an excellent impurity removal effect can be achieved by recycling waste slag and raw material in the preceding and subsequent processes without the introduction of an external impurity removal agent. The removal rates of Cu, Fe, and Al impurities can reach 99% or more. The loss of precious metals is low, and the total amount of Ni, Co, and Mn in the washed iron and aluminum slag is less than 1.5% by weight. The Cu mass / Ni mass ratio in the washed copper slag is greater than 15, and the precious metal recovery rate is increased by 0.5%. At the same time, the amount of alkali added and the amount of slag produced are reduced, where the amount of slag produced is reduced by 20% to 60%, and the overall economic efficiency is increased by 5%. Brief description of the drawings

[0043] [Fig. 1] is a flowchart showing a process for removing impurities from a used lithium battery leachate in various examples.

[0044] DETAILED DESCRIPTION OF EMBODIMENT MODES

[0045] In order to better illustrate the objectives, technical solutions, and advantages of this application, the present application will be further elaborated below with reference to specific examples and comparative examples, which are used for a thorough understanding of this application but do not limit its scope. All other examples obtained by a person skilled in the art without creative effort must fall within the scope of protection of this application. Unless otherwise specified, the reagents and experimental instruments involved in the examples of this application are conventional reagents and instruments in common use. Example 1

[0046] This example provides a method for removing impurities from a used lithium battery leachate, comprising the following steps:

[0047] (1) 10 m3 of a leachate from a spent ternary battery (with a pH value of 1.5) were added to 500 kg of wet slag (slag produced by a second copper removal in the previous batch, comprising copper sulfide, nickel sulfide, cobalt sulfide, iron hydroxide, and aluminum hydroxide, where the total mass percentage of nickel sulfide and cobalt sulfide was 74.5%) as a first impurity removal agent, and subjected to a first copper removal, where a reaction temperature was regulated at 80°C and a reaction time of 4 h, so as to obtain copper slag and a first copper-free solution, where the copper slag was washed with water at a ratio of twice the mass of the copper slag, water after washing was used as a solvent for a mixed solution of sodium carbonate and sodium sulfide during a deep impurity removal, and the copper slag after washing was used to recover further copper ;

[0048] (2) the first copper-free solution was added to 700 kg of slag wet (the slag produced by a thorough removal of impurities in the previous batch, including copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide, where a total mass percentage of nickel sulfide and cobalt sulfide was 84.3%, and a mass percentage total nickel hydroxide and cobalt hydroxide was 8.9%) as a second impurity removal agent, and subjected to a second copper removal, where a reaction temperature was regulated to 80°C and a reaction time was 4 h, so as to obtain slags and a second copper-free solution, where the slags (comprising copper sulfide, nickel sulfide, cobalt sulfide, iron hydroxide and aluminium hydroxide, where a total mass percentage of nickel sulfide and cobalt sulfide was 76.3%) were used as an impurity removal agent for the first copper removal in the next batch, i.e. as the first impurity removal agent for the first copper removal in the next batch;

[0049] (3) the second solution, free of copper, was added to a solution of 30% sodium carbonate by weight was used to remove iron and aluminum, and the pH value was adjusted to 4.0 to remove iron and aluminum. The reaction temperature was regulated at 85°C, and the reaction time was 4 h, so as to obtain iron and aluminum slag and a solution after the removal of copper, iron, and aluminum. The iron and aluminum slag was washed with water at a rate of twice the mass of iron and aluminum slag in a three-stage backwashing method. The water after washing was added to spent lithium battery leachate in the next batch and subjected to the first copper removal in the following batch. The iron and aluminum slag after washing (total Ni, Co, and Mn content < 1.5% by weight) was general solid waste and was used to manufacture ceramic granules.

[0050] (4) the solution after the removal of copper, iron and aluminum was added to One cubic meter of a mixed solution of sodium carbonate and sodium sulfide (sodium carbonate content of 50 kg / m³ and sodium sulfide content of 70 kg / m³) was subjected to thorough impurity removal. The reaction temperature was regulated at 85°C, the reaction time was 2 hours, and the pH at the reaction endpoint was 6.0. This process yielded slag and a solution after thorough impurity removal. The slag (comprising components with the following contents: copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide, and cobalt hydroxide, with a total mass percentage of nickel sulfide and cobalt sulfide of 88.2% and a total mass percentage of nickel hydroxide and cobalt hydroxide of 7.5%) was used as the agent. for the removal of impurities for the second copper removal in the following batch,that is, the second impurity removal agent for the second copper removal in the following batch; and the solution, after the deep removal of impurities was used to recover more nickel, cobalt, manganese and lithium.

[0051] [Tables 1] Cu Fe Al Ni Co Mn Leachate mg / L 5184 5092 3191 52895 22625 14402 First solution free of copper mg / L 859 4842 3247 56415 23656 14391 Second solution free of copper mg / L 0.86 4493 2187 60641 24301 14932 Solution after removal of copper, iron and aluminum mg / L 0.54 12.32 7.43 57721 23453 14532 Solution after deep removal of impurities mg / L 0.41 1.03 0.62 52475 22403 14350 Copper slag after washing % by weight 15.44 2.43 0.81 0.78 Mass of Cu / Mass of Ni in copper slag after washing 19.8

[0052] Test data for the impurity removal process in Example 1 Example 2

[0053] This example provides a method for removing impurities from a used lithium battery leachate, comprising the following steps:

[0054] (1) 10 m3 of a leachate from a spent ternary battery (with a pH value of 1.5) were added to 700 kg of wet slag (slag produced by a second copper removal in the previous batch, comprising copper sulfide, nickel sulfide, cobalt sulfide, iron hydroxide, and aluminum hydroxide, where the total mass percentage of nickel sulfide and cobalt sulfide was 72.0%) as a first impurity removal agent, and subjected to a first copper removal, where a reaction temperature was regulated at 80°C and a reaction time of 5 h, so as to obtain copper slag and a first copper-free solution, where the copper slag was washed with water at a ratio of 6 times the mass of the copper slag, the water after washing was used as a solvent for a mixed solution of sodium carbonate and sodium sulfide during from a thorough removal of impurities, and the copper slag after washing was used to recover more copper;

[0055] (2) the first solution, free of copper, was added to 800 kg of slag wet (the slag produced by a thorough removal of impurities from the previous batch, comprising copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide, and cobalt hydroxide, where a total mass percentage of nickel sulfide and cobalt sulfide was 86.5%, and a total mass percentage of nickel hydroxide and cobalt hydroxide was 6.3%) as a second impurity-removing agent, and subjected to a second copper removal, where a reaction temperature was regulated at 80°C and a reaction time was 5 h, so as to obtain slag and a second copper-free solution, where the slag (comprising copper sulfide, nickel sulfide, cobalt sulfide, iron hydroxide, and aluminum hydroxide, where a total mass percentage of nickel sulfide and cobalt sulfide was 78,2%) were used as a scavenging agent for the first copper removal in the next batch, i.e., as the first scavenging agent for the first copper removal in the next batch;

[0056] (3) the second solution, free of copper, was added to a solution of 30% sodium carbonate by weight was used to remove iron and aluminum, and the pH value was adjusted to 4.5 to remove iron and aluminum. The reaction temperature was regulated at 85°C, and the reaction time was 4 h, so as to obtain iron and aluminum slag and a solution after the removal of copper, iron, and aluminum. The iron and aluminum slag was washed with water at a ratio of 6 times the mass of iron and aluminum slag in a three-stage backwashing method. The water after washing was added to spent lithium battery leachate in the next batch and subjected to the first copper removal in the following batch. The iron and aluminum slag after washing (total Ni, Co, and Mn content < 1.5% by weight) was general solid waste and was used to manufacture ceramic granules.

[0057] (4) the solution after the removal of copper, iron and aluminum was added to 1 m3 of a mixed solution of sodium carbonate and sodium sulfide (the sodium carbonate content was 50 kg / m3 and the sodium sulfide content was 70 kg / m3) and subjected to a thorough removal of impurities, where a reaction temperature was regulated at 85°C, a reaction time was 2 h and the pH value at an endpoint of reaction was 6.0, so as to obtain slag and a solution after the thorough removal of impurities, where the slag (comprising components having the following contents: copper sulfide, nickel sulfide, Cobalt sulfide, nickel hydroxide, and cobalt hydroxide, where a total mass percentage of nickel sulfide and cobalt sulfide was 86.6%, and a total mass percentage of nickel hydroxide and cobalt hydroxide was 8.6%), were used as an impurity removal agent for the second copper removal in the next batch; and the solution after the deep removal of impurities was used to further recover nickel, cobalt, manganese, and lithium.

[0058] [Tables2] Cu Fe Al Ni Co Mn Leachate mg / L 7084 4092 4191 49823 21093 13947 First solution free of copper mg / L 654 3876 4067 56459 22371 13907 Second solution free of copper mg / L 0.57 3367 3156 62077 22916 14341 Solution after removal of copper, iron and aluminum mg / L 0.47 17.21 10.04 58780 22104 14470 Solution after thorough removal of impurities mg / L 0.45 0.72 0.55 50443 20039 13582 Copper slag after the first wash (% by weight): 16.37, 1.47, 1.26, 0.86. Mass of Cu / Mass of Ni in copper slag after washing: 19.0

[0059] Test data for the impurity removal process in example 2 Example 3

[0060] This example provides a method for removing impurities from a used lithium battery leachate, comprising the following steps:

[0061] (1) 10 m3 of a leachate from a spent ternary battery (with a pH value of 2.0) were added to 300 kg of wet slag (slag produced by a second removal of copper from the previous batch, comprising components having the following contents: copper sulfide, nickel sulfide, cobalt sulfide, iron hydroxide and aluminum hydroxide, where a total mass percentage of nickel sulfide and cobalt sulfide was 75.4%) as a first impurity removal agent, and subjected to a first copper removal, where a reaction temperature was regulated at 80°C and a reaction time was 4 h, so as to obtain copper slags and a first copper-free solution, where the copper slags were washed with water at a rate of 10 times the mass of the copper slags, the water after washing was used as a solvent for a mixed solution of sodium carbonate and sodium sulfide during a deep impurity removal, and the copper slags after washing were used to recover more copper;

[0062] (2) the first solution freed of copper was added to 550 kg of slag wet (the slag produced by a thorough removal of impurities in the previous batch, comprising copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide, where a total mass percentage of nickel sulfide and cobalt sulfide was 86%, and a total mass percentage of nickel hydroxide and cobalt hydroxide was 7.5%) as a second impurity removal agent, and subjected to a second copper removal, where a reaction temperature was regulated at 80°C and a reaction time was 4 h, so as to obtain slag and a second copper-free solution, where the slag (comprising copper sulfide, nickel sulfide, cobalt sulfide, iron hydroxide and aluminium hydroxide, where a total mass percentage of nickel sulfide and cobalt sulfide was 77,3%) were used as a scavenging agent for the first copper removal in the next batch, i.e., as the first scavenging agent for the first copper removal in the next batch;

[0063] (3) the second solution, free of copper, was added to a solution of 30% sodium carbonate by weight was used to remove iron and aluminum, and the pH value was adjusted to 4.5 to remove iron and aluminum. The reaction temperature was regulated at 85°C, and the reaction time was 4 h, so as to obtain iron and aluminum slag and a solution after the removal of copper, iron, and aluminum. The iron and aluminum slag was washed with water at a rate of 10 times the mass of iron and aluminum slag in a three-stage backwashing method. The water after washing was added to spent lithium battery leachate in the next batch and subjected to the first copper removal in the following batch. The iron and aluminum slag after washing (a total Ni, Co, and Mn content < 1.5% by weight) was general solid waste and was used to manufacture ceramic granules.

[0064] (4) the solution after the removal of copper, iron and aluminum was added to 1 m3 of a mixed solution of sodium carbonate and sodium sulfide (the (sodium carbonate content was 50 kg / m³ and sodium sulfide content was 70 kg / m³) and subjected to a deep removal of impurities, where a reaction temperature was regulated at 85°C, a reaction time of 2 h, and a pH value at the reaction endpoint of 6.5, so as to obtain slag and a solution after deep removal of impurities, where the slag (comprising copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide, and cobalt hydroxide, where a total mass percentage of nickel sulfide and cobalt sulfide was 85.2%, and a total mass percentage of nickel hydroxide and cobalt hydroxide was 6.7%) was used as a removing agent for the second copper removal in the following batch, i.e., the second agent removal of impurities for the second removal of copper in the following batch;and the solution after thorough removal of impurities was used to recover more nickel, cobalt, manganese and lithium.

[0065] [Tables3] Cu Fe Al Ni Co Mn Leachate mg / L 2355 3466 4988 54876 23876 16782 First solution free of copper mg / L 470 3365 4021 56692 23874 15990 Second solution free of copper mg / L 1.07 2872 3447 61382 24479 16722 Solution after removal of copper, iron and aluminum mg / L 0.89 11.55 6.34 59473 24027 15949 Solution after deep removal of impurities mg / L 0.78 2.11 0.44 56735 23521 15467 Slag of Copper after washing (% by weight): 10.39, 0.88, 1.58, 0.55. Mass of Cu / Mass of Ni in copper slag after washing: 18.9

[0066] Test data of the impurity removal process in example 3 Example 4

[0067] This example provides a method for removing impurities from a used lithium battery leachate, comprising the following steps:

[0068] (1) 10 m3 of a leachate from a spent ternary battery (with a pH value of 1.0) were added to 1200 kg of wet slag (slag produced by a second copper removal in the previous batch, comprising copper sulfide, nickel sulfide, cobalt sulfide, iron hydroxide, and aluminum hydroxide, where the total mass percentage of nickel sulfide and cobalt sulfide was 72.3%) as a first impurity removal agent, and subjected to a first copper removal, where the reaction temperature was regulated at 50°C and the reaction time was 5 h, so as to obtain copper slag and a first copper-free solution, where the copper slag was washed with water at a ratio of 10 times the mass of the copper slag, the water after washing was used as a solvent for a mixed solution of sodium carbonate and sodium sulfide during a deep impurity removal, and the copper slag after washing was used to recover further copper;

[0069] (2) the first solution freed of copper was added to 500 kg of slag wet (the slag produced by a thorough removal of impurities from the previous batch, comprising copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide, and cobalt hydroxide, where a total mass percentage of nickel sulfide and cobalt sulfide was 83.9%, and a total mass percentage of nickel hydroxide and cobalt hydroxide was 8.6%) as a second impurity-removing agent, and subjected to a second copper removal, where a reaction temperature was regulated at 50°C and a reaction time was 5 h, so as to obtain slag and a second copper-free solution, where the slag (comprising copper sulfide, nickel sulfide, cobalt sulfide, iron hydroxide, and aluminum hydroxide, where a total mass percentage of nickel sulfide and cobalt sulfide was 74,2%) were used as a scavenging agent for the first copper removal in the next batch, i.e., as the first scavenging agent for the first copper removal in the next batch;

[0070] (3) the second solution, free of copper, was added to a solution of 30% sodium carbonate by weight was used to remove iron and aluminum, and the pH was adjusted to 4.5 to further remove iron and aluminum. The reaction temperature was set at 80°C, and the reaction time was 5 hours. This yielded iron and aluminum slag and a solution after the removal of copper, iron, and aluminum. The iron and aluminum slag was then washed with water at a ratio of 10 times its mass using a three-stage countercurrent washing method. The washed water was then added to a battery leachate. lithium was used in the next batch and subjected to the first copper removal in the following batch, and iron and aluminum slags after washing (total Ni, Co and Mn content < 1.5% by weight) were general solid waste and were used to manufacture ceramic granules; and

[0071] (4) the solution after the removal of copper, iron and aluminum was added to 1 m3 of a mixed solution of sodium carbonate and sodium sulfide (the sodium carbonate content was 50 kg / m3 and the sodium sulfide content was 70 kg / m3) and subjected to deep impurity removal, where a reaction temperature was regulated at 70°C, a reaction time of 3 h and the pH value at the reaction endpoint was 6.0, so as to obtain slag and a solution after deep impurity removal, where the slag (comprising copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide, where a total mass percentage of nickel sulfide and cobalt sulfide was 82.3%, and a total mass percentage of nickel hydroxide and cobalt hydroxide was 12.5%) was used as an impurity removal agent for the second removal of copper in the following batch,that is, the second impurity removal agent for the second copper removal in the following batch; and the solution after the deep impurity removal was used to further recover nickel, cobalt, manganese, and lithium.

[0072] [Tables4] Cu Fe Al Ni Co Mn Leachate mg / L 10974 7427 7607 51286 23523 14876 First solution free of copper mg / L 773 6410 6726 66246 24664 15332 Second solution free of copper mg / L 2.44 5568 5219 68440 25265 15811 Solution after removal of copper, iron and aluminum mg / L 0.97 30.11 17.57 68561 25782 16878 Solution after thorough removal of impurities mg / L 0.55 1.26 0.96 58837 23373 15842 Copper slag after washing (% by weight): 26.32, 1.78, 1.39, 1.37 Cu mass / Ni mass in copper slag after washing 19.3

[0073] Test data for the impurity removal process in Example 4 Example 5

[0074] This example provides a method for removing impurities from a used lithium battery leachate, comprising the following steps:

[0075] (1) 10 m3 of a spent ternary battery leachate (with a pH value of 1.0) have were added to 300 kg of wet slag (the slag was prepared by adding an alkaline solution and sodium sulfide to a lithium battery leachate containing low levels of copper, iron, and aluminum, including copper sulfide, nickel sulfide, cobalt sulfide, iron hydroxide, and aluminum hydroxide, where the total mass percentage of nickel sulfide and cobalt sulfide was 76%) as a first impurity removal agent, and subjected to a first copper removal, where a reaction temperature was regulated at 90°C and a reaction time of 1 h, so as to obtain copper slag and a first copper-free solution, where the copper slag was washed with water at a ratio of 10 times the mass of the copper slag, the water after washing was used as a solvent for a mixed solution of sodium carbonate and sodium sulfide during a removal deep down to remove impurities,and the copper slag after washing was used to recover more copper;

[0076] (2) the first copper-free solution was added to 350 kg of slag wet (the slag was prepared by adding an alkaline solution and sodium sulfide to a lithium battery leachate containing low levels of copper, iron, and aluminum, comprising copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide, and cobalt hydroxide, where a total mass percentage of nickel sulfide and cobalt sulfide was 87.1%, and a total mass percentage of nickel hydroxide and cobalt hydroxide was 12.4%) as a second impurity removal agent, and subjected to a second copper removal, where a reaction temperature was regulated at 90°C and a reaction time was 1 h, so as to obtain slag and a second copper-free solution, where the slag (comprising copper sulfide, nickel sulfide, cobalt sulfide, iron hydroxide, and hydroxide) aluminum,where a total mass percentage of nickel sulfide and cobalt sulfide was 74.1%) were used as a scavenging agent for the first copper removal in the next batch, i.e., as the first scavenging agent for the first copper removal in the next batch; ,

[0077] (3) the second solution, free of copper, was added to a solution of sodium carbonate at 30% by weight to remove iron and aluminum, and the pH value was adjusted to 4.0 to remove iron and aluminum, where a reaction temperature was regulated at 95°C, and a reaction time was 1 h, so as to obtain iron and aluminum slags and a solution after the removal of copper, iron and aluminum, where the iron and aluminum slags were washed with water at a rate of 10 times the mass of iron and aluminum slags according to a three-stage backwashing method, the water after washing was added to a used lithium battery leachate in the next batch and subjected to the first copper removal in the next batch, and the iron and aluminum slags after washing (a total content of Ni, Co and Mn < 1.5% by weight) were general solid waste and were used to manufacture ceramic granules;

[0078] (4) the solution after the removal of copper, iron and aluminum was added to One cubic meter of a mixed solution of sodium carbonate and sodium sulfide (sodium carbonate content of 50 kg / m³ and sodium sulfide content of 70 kg / m³) was subjected to thorough impurity removal. The reaction temperature was regulated at 90°C, the reaction time was 1 hour, and the pH at the reaction endpoint was 6.5. This process yielded slag and a solution after thorough impurity removal. The slag (comprising components with the following contents: copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide, and cobalt hydroxide, with a total mass percentage of nickel sulfide and cobalt sulfide of 87.4% and a total mass percentage of nickel hydroxide and cobalt hydroxide of 7.7%) was used as the agent. for the removal of impurities for the second copper removal in the following batch,that is, the second impurity removal agent for the second copper removal in the following batch; and the solution after the deep impurity removal was used to further recover nickel, cobalt, manganese, and lithium; and,

[0079] (5) another batch of used lithium battery leachate was treated.

[0080] [Tables5] Cu Fe Al Ni Co Mn Leachate mg / L 2355 3466 4988 54876 23876 16782 First batch: first solution free of copper mg / L 517 3702 4423 59527 26261 17589 First batch: second solution free of copper mg / L 1.12 3016 3619 64451 25703 17558 First batch: Solution after removal of copper, iron, and aluminum mg / L 0.86 11.20 6.15 57689 23306 15471 First batch: Solution after thorough removal of impurities mg / L 0.62 1.69 0.35 51388 22817 15374 First batch: Copper slag after washing (% by weight) 11.95 1.01 1.82 0.63 First batch: Mass of Cu / mass of Ni in copper slag after washing 18.9 Second batch: First solution free of copper mg / L 3.55 3566 4632 63547 25647 17773 Second batch: Second solution free of copper mg / L 1.03 3278 3726 59432 27864 17843 Second batch: solution after removal of copper, iron and aluminum mg / L 0.87 15.40 8.83 57473 24691 16738 Second batch: solution after deep removal of impurities mg / L 0.55 2.34 1.45 1 24032 15949 Second batch: copper slag after washing in % by weight 13.23 1.01 1.82 0.82 Second batch: mass of Cu / mass of Ni in copper slag after washing 16.1

[0081] Test data for the impurity removal process in Example 5 Comparative Example 1

[0082] This comparative example provides a method for removing impurities from a used lithium battery leachate, comprising the following steps:

[0083] (1) 10 m3 of a spent ternary battery leachate (with a pH value of 1.0) have were added to 80 kg of iron powder to remove copper, where a reaction temperature was regulated to 50°C and a reaction time was 4 h, so as to obtain copper sponge slag and a copper-free solution, where the copper slag was washed with water at a rate of 10 times the mass of the copper slag;

[0084] (2) the copper-free solution was added to 180 L of hydrogen peroxide at 27.5% to oxidize ferrous ions, where a reaction temperature was regulated to 50°C and a reaction time was 2 h;

[0085] (3) the oxidized solution was added to 2.5 m3 of a sodium carbonate solution to 30% by weight to remove iron and aluminum, and the pH value was adjusted to 4.0-4.5 to remove iron and aluminum, where a reaction temperature was regulated at 95°C and a reaction time was 1 h, so as to obtain iron and aluminum slag and a solution after the removal of copper, iron, and aluminum, where the iron and aluminum slag was washed with water at a rate of 10 times the mass of iron and aluminum slag in a three-stage backwashing method, the water after washing was added to a spent lithium battery leachate in the next batch and subjected to the first copper removal in the following batch, and the iron and aluminum slag after washing was general solid waste and was used to manufacture ceramic granules; and

[0086] (4) the solution after the removal of copper, iron and aluminum was added to 1 m3 of a mixed solution of sodium carbonate and sodium sulfide (the sodium carbonate content was 50 kg / m3 and the sodium sulfide content was 20 kg / m3) and subjected to a deep removal of impurities, where a reaction temperature was regulated to 90°C, a reaction time was 1 h, and the pH value at an endpoint of reaction was 6.5, so as to obtain slag and a solution after the deep removal of impurities, where the slag was 200 kg.

[0087] [Tableauxô] Cu Fe Al Ni Co Mn Fe2+ Leachate mg / L 7084 4092 4191 49823 21093 13947 213 Solution after replacement mg / L 57 12583 4042 49369 21342 14028 11342 Oxidized solution mg / L 55 12576 3977 49672 21563 13876 23 Solution after iron and aluminum removal mg / L 55 17.9 8.56 48674 19467 13189 Solution after deep removal of impurities mg / L 0.76 3.43 2.12 48072 18772 12838 Copper sponge slag in % 85 7 0.6 0.5

[0088] Test data of the impurity removal process in comparative example 1

[0089] Compared to the present application, comparative example 1 has the following disadvantages:

[0090] ® after the addition of iron powder to replace copper, the ferrous ions represent 90% or more of the total iron in the solution after replacement, and hydrogen is also generated, which poses a safety risk;

[0091] ® ferrous ions must be oxidized beforehand before the iron is removed, and the amount of hydrogen peroxide used is significant;

[0092] © the iron content in the oxidized solution is 200% higher than that in the leachate, and therefore the increase in iron and aluminum slag content is not less than 100% in the iron and aluminum removal process, leading to a large amount of iron and aluminum slag, a long operating cycle and an increase in the amount of water used for washing;

[0093] ® the quantity of alkaline solution used is increased by 2.5 times and the cost of auxiliary material is high;

[0094] ® after washing, nickel, cobalt and other precious metals removed by the Iron and aluminum slags increase considerably compared to example 2, and this portion of the precious metals cannot be recovered efficiently; and

[0095] © the concentrations of nickel, cobalt and other precious metals are reduced further in the solution after deep removal of impurities, the slag from deep removal of impurities is returned to the leaching process for recovery, and some of the nickel and cobalt in it will be lost with the leaching slag. Comparative example 2

[0096] This comparative example provides a method for removing impurities from a used lithium battery leachate, comprising the following steps:

[0097] (1) 10 m3 of a spent ternary battery leachate (with a pH value of 1.5) have were added to 700 kg of wet slag (comprising copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide, and cobalt hydroxide, where the total mass percentage of nickel sulfide and cobalt sulfide was 82.4%, and the total mass percentage of nickel hydroxide and cobalt hydroxide was 6.8%) as a second impurity removal agent, and subjected to copper removal, where a reaction temperature was regulated at 80°C and a reaction time of 4 h, so as to obtain copper slag and a solution after the removal of the copper, where the copper slag was washed with water at a rate of 10 times the mass of the copper slag, and the copper slag after washing was used to recover more copper;

[0098] (2) the solution after the removal of copper was added to a carbonate solution of sodium at 30% by weight to remove iron and aluminum, and the pH value was adjusted to 4.5 to remove iron and aluminum, where a reaction temperature was regulated at 85°C and a reaction time of 4 h, so as to obtain iron and aluminum slags and a solution after the removal of copper, iron, and aluminum; and

[0099] (3) the solution after the removal of copper, iron and aluminum was added to 1 m3 of a mixed solution of sodium carbonate and sodium sulfide (the sodium carbonate content was 50 kg / m3 and the sodium sulfide content was 70 kg / m3) and subjected to a deep removal of impurities, where a reaction temperature was regulated at 85°C, a reaction time was 2 h and the pH value at an endpoint of reaction was 6.0, so as to obtain slags and a solution after the deep removal of impurities, where the solution after the deep removal of impurities was used to recover more nickel, cobalt, manganese and lithium.

[0100] [Tables?] Cu Fe Al Ni Co Mn Leachate mg / L 5184 5092 3191 52895 22625 14402 Solution after copper removal mg / L 1.77 4387 2671 62726 23575 14862 Mass of Cu / Mass of Ni in copper slag after washing 1.3

[0101] Test data of the impurity removal process in comparative example 2

[0102] Compared to Example 1, the second impurity-removing agent is used as the impurity-removing agent during the first copper removal in Comparative Example 2. The nickel content in the resulting copper slag is higher, and the precious metal loss is greater. This is explained by the fact that to remove the copper more completely, it is necessary to add an excess of impurity-removing agent, and consequently, the nickel content is higher. In copper slag after copper removal, the Cu / Ni (mass ratio) is low. In the present application, impurities are removed in two stages. First, copper is removed more thoroughly in the second copper removal process with an excess of impurity removal agent, and then most of the copper in the leachate is removed in the first copper removal process. This ensures that the first impurity removal agent added in the first stage has a high nickel replacement efficiency, and the final copper slag has a high Cu / Ni (mass ratio).

[0103] Finally, it should be noted that the above examples are used solely to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been elaborated in detail with reference to the preferred examples, it should be understood that the technical solutions of this application can be modified and replaced without departing from the substance and scope of the technical solutions of this application.

Claims

1. Demands A process for removing impurities from a leachate of a used lithium battery, comprising the following steps: carrying out a first removal of copper on a leachate from a used lithium battery by adding a first impurity removal agent, so as to obtain copper slags and a first solution free of copper; carrying out a second copper removal on the first copper-free solution by adding a second impurity removal agent, so as to obtain slag and a second copper-free solution, where the resulting slag is used as the first impurity removal agent for the spent lithium battery leachate in the next batch to remove impurities; adjusting the pH of the second solution freed from copper by adding an alkali to precipitate iron and aluminum, so as to obtain iron and aluminum slags and a solution after the removal of iron, aluminum and copper; of achieving a thorough removal of impurities from the solution after the removal of iron, aluminum, and copper by adding sodium carbonate and sodium sulfide, so as to obtain slag and a solution after the thorough removal of impurities, where the resulting slag is used as a second impurity-removing agent for the spent lithium battery leachate in the next batch to remove impurities; and use of the solution after thorough removal of impurities to recover nickel, cobalt, manganese and lithium; in which the first impurity-removing agent comprises copper sulfide, nickel sulfide, cobalt sulfide, iron hydroxide and aluminium hydroxide, and a total mass percentage of nickel sulfide and cobalt sulfide in the first impurity-removing agent is greater than or equal to 70%; The second impurity removal agent comprises copper sulfide, nickel sulfide, cobalt sulfide, and hydroxide. of nickel and cobalt hydroxide, and a total mass percentage of nickel sulfide and cobalt sulfide in the second impurity removal agent is greater than or equal to 80%, and a total mass percentage of nickel hydroxide and cobalt hydroxide in the second impurity removal agent is between 5% and 15%.

2. A method for removing impurities from the spent lithium battery leachate according to claim 1, wherein a mass on a wet basis of the first added impurity removal agent represents 3% to 20% relative to a mass of the spent lithium battery leachate; and during the first copper removal, a reaction temperature is between 50 and 90°C and a reaction time is between 1 and 5 h.

3. A method for removing impurities from the spent lithium battery leachate according to claim 1, wherein a mass on a wet basis of the second added impurity removal agent represents 3.5% to 40% relative to a mass of the spent lithium battery leachate; and during the second copper removal, a reaction temperature is between 50 and 90°C and a reaction time is between 1 and 5 h.

4. A method for removing impurities from the leachate of a used lithium battery according to claim 1, wherein, in the process of adjusting the pH of the second solution freed of copper by adding an alkali to precipitate iron and aluminum, the pH value is adjusted to 4.0-4.5 by adding the alkali, a reaction temperature is between 80 and 95°C and a reaction time is between 1 and 5 h.

5. A method for removing impurities from the leachate of used lithium batteries according to claim 1, wherein, in the process of adjusting the pH of the second copper-free solution by adding an alkali to precipitate iron and aluminum, the alkali used is at least one of sodium carbonate and sodium hydroxide.

6. A method for removing impurities from the leachate of a used lithium battery according to claim 1, wherein, during the deep removal of impurities, a reaction temperature is between 70 and 90°C, a reaction time is between 1 and 3 h, and The pH value at a reaction endpoint is between 6.0 and 6.

5.

7. A method for removing impurities from the spent lithium battery leachate according to claim 1, wherein the spent lithium battery leachate has a pH from 1.0 to 2.0 and comprises components having the following contents: Ni from 35 to 65 g / L, Co from 15 to 35 g / L, Mn from 10 to 25 g / L, Cu from 0 to 10 g / L (greater than 0), Fe from 0 to 10 g / L (greater than 0) and Al from 0 to 10 g / L (greater than 0); the first copper-free solution satisfies: Cu < 1 g / L, and the first copper slags are washed with water and then satisfy: mass of Cu / mass of Ni > 15; and the second copper-free solution satisfies: Cu < 2 mg / L; and the solution after thorough removal of impurities satisfies: Cu < 0.5 mg / L, Fe < 3 mg / L and Al < 1 mg / L.

8. A method for removing impurities from the leachate of a used lithium battery according to claim 1, wherein at least one of the conditions (a) and (b) is satisfied: (a) during the deep removal of impurities, the added sodium carbonate and sodium sulfide constitute a mixed solution of sodium carbonate and sodium sulfide, and in the mixed solution of sodium carbonate and sodium sulfide, a mass percentage of sodium carbonate is between 5% and 20%, and a mass percentage of sodium sulfide is between 5% and 20%; the copper slags are washed with water and subjected to solid-liquid separation, so as to obtain washed copper slags and water after washing the copper slags; the washed copper slags are used to recover the copper, and the water after washing the copper slags is used as a solvent for the mixed solution of sodium carbonate and sodium sulfide during the deep removal of impurities; and (b) iron and aluminium slags are washed with water and subjected to solid-liquid separation, so as to obtain washed iron and aluminium slags and water after washing the iron and aluminium slags, and the water after washing the iron and aluminium slags is added to a spent lithium battery leachate in the next batch for the removal of impurities.

9. A method for removing impurities from the leachate of a used lithium battery according to claim 8, wherein, in the case where copper slag is washed with water, a mass of the water used is 2 to 10 times the mass on a wet basis of the copper slag; and in the case where iron and aluminum slag are washed with water, a washing process used is a three-stage countercurrent washing, and a mass of the water used is 2 to 10 times the mass on a wet basis of the iron and aluminum slag.

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