A method for removing impurities from waste lithium battery leachate

Abstract

The present invention discloses a method for removing impurities from a waste lithium battery leachate, and relates to the technical field of wet impurity removal. The method for removing impurities from a waste lithium battery leachate comprises adding a first impurity remover to the waste lithium battery leachate for first-stage copper removal, adding a second impurity remover to the solution obtained from the first-stage copper removal for second-stage copper removal, adding alkali to the solution obtained from the second-stage copper removal to adjust the pH to precipitate iron and aluminum, adding soda ash and sodium sulfide to the solution obtained from the iron and aluminum removal by adding alkali for deep impurity removal, and the solution obtained from the deep impurity removal is used to recover nickel, cobalt, manganese, and lithium. The slag obtained from the second-stage copper removal is used as the first impurity remover for the next batch of impurity removal, and the slag obtained from the deep impurity removal is used as the first impurity remover for the next two batches of impurity removal. Through the cyclic iteration of waste residues and raw materials from the previous and subsequent processes, an excellent impurity removal effect can be achieved without introducing an external impurity remover, and no impurity metals are added, thereby reducing the loss of valuable metals, the amount of alkali added, and the amount of slag produced. The impurity removal process is safe and has higher overall economic benefits.

Description

Technical Field

[0001] The invention relates to the technical field of wet impurity removal, and in particular to a method for removing impurities from waste lithium battery leachate. Background Art

[0002] The cathode active material of ternary lithium batteries is a key component of the battery, containing large amounts of valuable metals such as nickel, cobalt, manganese, and lithium. Recycling these valuable metals from waste battery materials and realizing their resource utilization will have significant environmental and economic benefits, and is of far-reaching significance.

[0003] The recovery of valuable metals in the positive active materials of waste lithium batteries usually requires pre-treatment separation such as crushing, disassembly, and screening, and then the valuable metals are recovered through hydrometallurgy. However, in the pre-treatment separation part, due to the limited effect of mechanical separation, impurities such as copper, iron, and aluminum will be partially mixed into the black powder, and enter the leachate in the subsequent leaching treatment. In order to achieve the recycling of nickel, cobalt, and manganese, the copper, iron, and aluminum in the leachate must be removed. At present, the copper in the leachate of ternary battery materials is mainly removed by iron powder replacement, sodium sulfide copper removal, and other methods. However, these methods have the following problems:

[0004] In the iron powder replacement method, the amount of iron powder added is large, and the amount of leaching solution added per ton of material is 50-100kg, which leads to an increase of 20-60% in the iron slag produced by the ton of material processing. The increase in slag will take away more valuable metals such as nickel and cobalt, resulting in a large loss of valuable metals such as nickel and cobalt. Due to the presence of Fe in the leaching solution, 3+ , the added iron powder will be mixed with Fe 3+ The reaction leads to an increase in the amount of iron powder added and a further increase in the amount of iron slag. In production practice, 10% of the iron powder and Fe 3+ Reacts to Fe 2+ , and a large amount of Fe 2+ It is necessary to add an oxidant to oxidize it before it can be completely removed in the iron and aluminum removal process, which increases the oxidation process and the use of oxidants, extends the entire operation time by 20-40%, and increases the waiting time and labor intensity. When deep impurity removal is performed after iron and aluminum removal, the deep impurity removal slag produced contains a large amount of nickel and cobalt sulfide, and can only be recycled back to the front stage of leaching, resulting in a reduction in the battery material processing capacity. The deep impurity removal slag contains sodium sulfide, nickel sulfide, cobalt sulfide and copper sulfide, and when it is returned to the front stage of leaching for treatment, it will lead to increased consumption of acid and oxidants, and increased costs.

[0005] In the sodium sulfide copper removal method, sulfuric acid exists in the leachate, which reacts with sodium sulfide to produce the highly toxic gas hydrogen sulfide, which has poor safety. The nickel and cobalt content in the leachate is relatively high. After the copper concentration decreases, nickel, cobalt, etc. will form sulfides and precipitate together with copper, resulting in the loss of valuable metals and reducing the recovery rate.

[0006] Therefore, finding a method for removing impurities from waste lithium battery leachate without increasing impurity metals and without losing the valuable metals to be recovered to ensure low cost, high yield and safety is a difficult problem that needs to be solved urgently in the industry. Summary of the Invention

[0007] Based on the defects of the prior art, the purpose of the present invention is to provide a method for removing impurities from waste lithium battery leachate, which not only does not increase impurity metals, but also has a high recovery rate of valuable metals such as nickel and cobalt, low cost and high safety.

[0008] In order to achieve the above object, the present invention provides a method for removing impurities from waste lithium battery leachate, comprising the following steps:

[0009] A first impurity remover is added to the waste lithium battery leachate to perform a first stage of copper removal to obtain copper slag and a first copper-removed solution;

[0010] Adding a second impurity remover to the first copper-removed solution for two-stage copper removal to obtain a slag and a second copper-removed solution, wherein the obtained slag is used as a first impurity remover for impurity removal of the next batch of waste lithium battery leachate;

[0011] adding alkali to the second copper-removed solution to adjust the pH to precipitate iron and aluminum, thereby obtaining iron-aluminum slag and a solution after removing iron, aluminum, and copper;

[0012] Adding soda ash and sodium sulfide to the solution after removing iron, aluminum and copper for deep impurity removal to obtain a slag and a solution after deep impurity removal, and using the obtained slag as a second impurity remover for removing impurities in the next batch of waste lithium battery leachate;

[0013] Using the deeply impurity-removed solution to recover nickel, cobalt, manganese and lithium;

[0014] Wherein, the first impurity remover comprises copper sulfide, nickel sulfide, cobalt sulfide, ferric hydroxide and aluminum hydroxide, and the total mass percentage of nickel sulfide and cobalt sulfide in the first impurity remover is greater than 70%;

[0015] The second impurity remover comprises copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide. The total mass percentage of nickel sulfide and cobalt sulfide in the second impurity remover is above 80%, and the total mass percentage of nickel hydroxide and cobalt hydroxide is 5-15%.

[0016] The main component of the first impurity remover is nickel cobalt sulfide. Without adding iron powder, most of the copper in the waste lithium battery leachate is replaced by the reaction of nickel cobalt sulfide with copper ions, and nickel cobalt sulfide is converted into copper sulfide.

[0017] The second impurity remover is used to further remove copper from the leachate, so that the copper is further removed into the slag (i.e., the first impurity remover used for the next batch of impurity removal).

[0018] In addition to completely removing copper, the sodium sulfide added in the deep impurity removal also generates by-products, nickel and cobalt sulfides, which are returned to the second stage copper removal process, allowing nickel and cobalt to return to the leachate, reducing the loss of nickel and cobalt. At the same time, the soda ash added not only removes iron and aluminum in the deep process, but also generates by-products, nickel hydroxide and cobalt hydroxide, which are returned to the second stage copper removal process, consuming the residual acid in the leachate to a certain extent, reducing the amount of alkali used for iron and aluminum removal, and allowing nickel and cobalt to return to the leachate, reducing the loss of nickel and cobalt.

[0019] The above method realizes the iterative recycling of impurity removers without increasing impurity metals by recycling the second impurity remover produced by deep impurity removal into the second copper removal process for deep copper removal, and recycling the first impurity remover produced in the second copper removal process into the first copper removal process for preliminary copper removal, thereby achieving the iterative recycling of impurity removers; at the same time, the nickel and cobalt sulfided into the slag in the deep impurity removal process are returned to the system through the two copper removal processes and are recovered, thereby reducing the loss of valuable metals.

[0020] The above method has high impurity removal effect, low loss rate of valuable metals, low consumption of auxiliary materials, less waste slag, shortened operation cycle, more economical equipment investment, no generation of toxic and harmful gases, and better safety.

[0021] Preferably, the first impurity remover is added in an amount of 3-20% by weight on a wet basis of the waste lithium battery leachate; the reaction temperature in the first copper removal step is 50-90°C, and the reaction time is 1-5 hours. When the first copper removal step is carried out under these process conditions, copper in the leachate can be better removed, reducing the copper content to less than 1g / L, and the copper slag produced carries away less valuable metals. For example, after washing the copper slag with water, the ratio of Cu content to Ni content is greater than 15. Optionally, the first impurity remover can be added in an amount of 3-15% or 3-12% by weight of the waste lithium battery leachate. Optionally, the first impurity remover can be added in an amount of 5%, 10%, 13%, 16%, or 18% by weight of the waste lithium battery leachate.

[0022] In this article, the calculation method of "the added wet basis mass of the first impurity remover is 3-20% of the amount of the waste lithium battery leachate" is as follows: grams of the added wet basis of the first impurity remover / milliliters of the waste lithium battery leachate × 100%. The calculation methods for other similar expressions are the same.

[0023] Preferably, the amount of the second impurity remover added on a wet basis is 3.5-40% of the amount of the waste lithium battery leachate; the reaction temperature in the second-stage copper removal process is 50-90°C, and the reaction time is 1-5 hours. When the first-stage impurity removal is carried out under these process conditions, copper can be removed more deeply, reducing the copper content in the leachate to less than 2 mg / L. Optionally, the amount of the second impurity remover added on a wet basis can also be 3.5-30%, 3.5-20%, or 3.5-10% of the amount of the waste lithium battery leachate. Optionally, the amount of the second impurity remover added on a wet basis can also be 5%, 10%, 13%, 16%, 18%, 21%, 25%, 28%, 31%, 35%, or 38% of the amount of the waste lithium battery leachate.

[0024] In this article, the calculation method of "the added wet basis mass of the second impurity remover is 3.5-40% of the amount of the waste lithium battery leachate" is as follows: grams of the added wet basis of the second impurity remover / milliliters of the waste lithium battery leachate × 100%. The calculation methods for other similar expressions are the same.

[0025] Preferably, in the second step of adding alkali to the solution after copper removal to adjust the pH to cause iron and aluminum precipitation, the alkali is added to adjust the pH to 4.0-4.5, the reaction temperature is 80-95°C, and the reaction time is 1-5 hours. Under these specific process conditions, the iron and aluminum removal step can better remove iron and aluminum from the leachate, and the total amount of Ni, Co, and Mn in the resulting iron and aluminum slag after cleaning is less than 1.5wt%.

[0026] Preferably, in the step of adding alkali to the second copper-removed solution to adjust the pH to precipitate iron and aluminum, the alkali used is at least one of soda ash and sodium hydroxide.

[0027] Preferably, in the step of adding alkali to the second copper-removed solution to adjust the pH to precipitate iron and aluminum, the alkali used is an alkali solution, and the mass percentage of alkali in the alkali solution is above 15%.

[0028] Preferably, in the deep impurity removal process, the reaction temperature is 70-90°C, the reaction time is 1-3 hours, and the reaction endpoint pH is 6.0-6.5. Under these specific process conditions, the deep impurity removal process can better remove copper, iron, and aluminum from the leachate, reducing the copper content in the leachate to less than 0.5 mg / L, the iron content to less than 3 mg / L, and the aluminum content to less than 1 mg / L.

[0029] Preferably, the pH value of the waste lithium battery leachate is 1.0-2.0, and includes the following components: Ni 35-65g / L, Co 15-35g / L, Mn 10-25g / L, Cu 0-10g / L and greater than 0, Fe 0-10g / L and greater than 0, Al 0-10g / L and greater than 0; Cu in the first solution after copper removal is <1g / L, and the mass of Cu contained in the copper slag after washing with water / the mass of Ni contained is >15; Cu in the second solution after copper removal is <2mg / L; in the solution after deep impurity removal, Cu <0.5mg / L, Fe <3mg / L, and Al <1mg / L.

[0030] Preferably, the method for removing impurities from the waste lithium battery leachate further satisfies at least one of the conditions (a) and (b):

[0031] (a) in the deep impurity removal process, the soda ash and sodium sulfide added are a mixed solution of soda ash and sodium sulfide, the mass percentage of soda ash in the mixed solution of soda ash and sodium sulfide is 5-20%, and the mass percentage of sodium sulfide is 5-20%; the copper slag is washed with water, and solid-liquid separation is performed to obtain washed copper slag and copper slag wash water, the washed copper slag is used to recover copper, and the copper slag wash water is used as a solvent for the mixed solution of soda ash and sodium sulfide used in the deep impurity removal process;

[0032] (b) washing the iron-aluminum slag with water, separating the solid and the liquid, obtaining washed iron-aluminum slag and iron-aluminum slag washing water, and adding the obtained iron-aluminum slag washing water to the next batch of waste lithium battery leachate for impurity removal.

[0033] The washing water obtained by washing the copper slag produced by the first stage copper removal with water can be used as the solvent for the mixed solution of soda ash and sodium sulfide used in the deep impurity removal process, which not only reduces the water consumption but also reduces the generation of wastewater.

[0034] The iron and aluminum slag washing water contains valuable metals, which are returned to the next batch of copper removal process to recover the valuable metals and further reduce the loss of valuable metals.

[0035] Preferably, when the copper slag is washed with water, the mass of the water used is 2-10 times the wet mass of the copper slag. This not only effectively washes the copper slag but also avoids excessive use of water.

[0036] Preferably, when the iron-aluminum slag is washed with water, the washing method used is three-stage countercurrent washing, and the mass of the water used is 2-10 times the wet mass of the iron-aluminum slag. This can not only effectively clean the iron-aluminum slag, but also avoid excessive use of water.

[0037] There is no special requirement for the initial sources of the first impurity remover and the second impurity remover, such as from low copper, iron, aluminum lithium battery positive electrode sheet leachate (Cu <0.1g / L, Fe <0.5g / L, Al <1g / L) by adding alkali solution and sodium sulfide, but it is not limited to this.

[0038] Compared with the existing technology, the beneficial effects of the present invention are: the present invention can achieve a very good impurity removal effect through the recycling of waste slag and raw materials from previous and subsequent processes without introducing external impurity removers. The impurity removal rate of Cu, Fe and Al can reach more than 99%, and the loss of valuable metals is small. The total amount of Ni, Co and Mn in the obtained cleaned iron-aluminum slag is <1.5wt%, and the Cu mass / Ni mass in the obtained cleaned copper slag is >15. The recovery rate of valuable metals is increased by 0.5%. At the same time, the amount of alkali added and the amount of slag produced are reduced, among which the slag produced is reduced by 20-60%, and the comprehensive economic benefits are improved by 5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Flowchart of the method for removing impurities from waste lithium battery leachate in each embodiment. DETAILED DESCRIPTION

[0040] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments and comparative examples. Its purpose is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative work premise all fall within the protection scope of the present invention. The experimental reagents and instruments involved in the implementation of the present invention are all conventional common reagents and instruments unless otherwise specified.

[0041] Example 1

[0042] This embodiment provides a method for removing impurities from waste lithium battery leachate, comprising the following steps:

[0043] (1) In the waste ternary battery material leachate (pH value = 1.5) 10m 3 adding 500 kg of wet slag of the first impurity remover (slag produced by the second stage copper removal of the previous batch, containing copper sulfide, nickel sulfide, cobalt sulfide, ferric hydroxide and aluminum hydroxide, wherein the total mass percentage of nickel sulfide and cobalt sulfide is 74.5%) to carry out the first stage copper removal, controlling the reaction temperature to 80° C. and the reaction time to 4 h to obtain copper slag and a solution after the first copper removal, wherein the copper slag is washed with water twice its mass, the washing water after washing is used as a solvent for the mixed solution of soda ash and sodium sulfide in the deep impurity removal process, and the washed copper slag is used for further copper recovery;

[0044] (2) adding 700 kg of wet slag of the second impurity remover (the slag produced by the previous batch of deep impurity removal, including copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide, wherein the total mass percentage of nickel sulfide and cobalt sulfide is 84.3%, and the total mass percentage of nickel hydroxide and cobalt hydroxide is 8.9%) to the solution after the first copper removal, and performing two-stage copper removal, controlling the reaction temperature to 80° C. and the reaction time to 4 h, to obtain slag and the solution after the second copper removal, wherein the slag (including copper sulfide, nickel sulfide, cobalt sulfide, ferric hydroxide and aluminum hydroxide, wherein the total mass percentage of nickel sulfide and cobalt hydroxide is 76.3%) is used as the impurity remover for the next batch of one-stage copper removal, i.e., the first impurity remover for the next batch of one-stage copper removal;

[0045] (3) adding 30 wt% soda ash solution to the solution after the second copper removal to remove iron and aluminum, adjusting the pH value to 4.0 to remove iron and aluminum, controlling the reaction temperature to 85 ° C., and the reaction time to 4 h to obtain iron-aluminum slag and a solution after copper and iron-aluminum removal, wherein the iron-aluminum slag is washed in a three-stage countercurrent manner and washed with water twice its mass, and the washing water after washing is added to the next batch of waste lithium battery leachate to remove copper in the next batch, and the washed iron-aluminum slag (the total amount of Ni, Co and Mn is <1.5 wt%) is used as general solid waste to make ceramsite;

[0046] (4) Add 1m 3 Mixed solution of soda ash and sodium sulfide (soda ash content 50kg / m 3 , sodium sulfide content 70kg / m 3 ) for deep impurity removal, controlling the reaction temperature to 85° C., the reaction time to 2 h, and the reaction endpoint pH to 6.0 to obtain a slag and a solution after deep impurity removal, wherein the slag (comprising the following components: copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide, with the total mass percentage of nickel sulfide and cobalt sulfide being 88.2% and the total mass percentage of nickel hydroxide and cobalt hydroxide being 7.5%) is used as an impurity remover for the next batch of second-stage copper removal, i.e., the second impurity remover for the next batch of second-stage copper removal; and the solution after deep impurity removal is used for further recovery of nickel, cobalt, manganese and lithium.

[0047] Table 1 Example 1 impurity removal process test data

[0048]

[0049] Example 2

[0050] This embodiment provides a method for removing impurities from waste lithium battery leachate, comprising the following steps:

[0051] (1) In the waste ternary battery material leachate (pH value = 1.5) 10m 3700 kg of wet slag with the first impurity remover (slag produced by the second-stage copper removal of the previous batch, including copper sulfide, nickel sulfide, cobalt sulfide, ferric hydroxide and aluminum hydroxide, wherein the total mass percentage of nickel sulfide and cobalt sulfide is 72.0%) is added to the reaction mixture for first-stage copper removal, the reaction temperature is controlled at 80° C., the reaction time is 5 h, and copper slag and a solution after the first copper removal are obtained, wherein the copper slag is washed with water 6 times its mass, the washing water after washing is used as a solvent for the mixed solution of soda ash and sodium sulfide in the deep impurity removal process, and the washed copper slag is used for further copper recovery;

[0052] (2) adding 800 kg of wet slag of the second impurity remover (the slag produced by the previous batch of deep impurity removal, including copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide, wherein the total mass percentage of nickel sulfide and cobalt sulfide is 86.5%, and the total mass percentage of nickel hydroxide and cobalt hydroxide is 6.3%) to the solution after the first copper removal, and performing two-stage copper removal, controlling the reaction temperature to 80° C. and the reaction time to 5 h, to obtain slag and the second copper removal solution, wherein the slag (including copper sulfide, nickel sulfide, cobalt sulfide, ferric hydroxide and aluminum hydroxide, wherein the total mass percentage of nickel sulfide and cobalt hydroxide is 78.2%) is used as the impurity remover for the next batch of one-stage copper removal, i.e., the first impurity remover for the next batch of one-stage copper removal;

[0053] (3) After the second copper removal, a 30 wt% soda ash solution is added to the solution to remove iron and aluminum, and the pH value is adjusted to 4.5 to remove iron and aluminum. The reaction temperature is controlled to 85° C. and the reaction time is 4 h to obtain iron-aluminum slag and a solution after copper and iron-aluminum removal. The iron-aluminum slag is washed in a three-stage countercurrent manner and washed with water 6 times its mass. The washing water after washing is added to the next batch of waste lithium battery leachate to remove copper in the next batch. The washed iron-aluminum slag (the total amount of Ni, Co and Mn is <1.5 wt%) is used as general solid waste to make ceramsite;

[0054] (4) Add 1m 3 Mixed solution of soda ash and sodium sulfide (soda ash content 50kg / m 3 , sodium sulfide content 70kg / m 3 ) for deep impurity removal, controlling the reaction temperature to 85° C., the reaction time to 2 h, and the reaction endpoint pH to 6.0 to obtain a slag and a solution after deep impurity removal, wherein the slag (comprising the following components: copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide, and cobalt hydroxide, with the total mass percentage of nickel sulfide and cobalt sulfide being 86.6%, and the total mass percentage of nickel hydroxide and cobalt hydroxide being 8.6%) is used as an impurity remover for the next batch of second-stage copper removal, i.e., the second impurity remover for the next batch of second-stage copper removal; and the solution after deep impurity removal is used for further recovery of nickel, cobalt, manganese, and lithium.

[0055] Table 2 Example 2 impurity removal process test data

[0056]

[0057] Example 3

[0058] This embodiment provides a method for removing impurities from waste lithium battery leachate, comprising the following steps:

[0059] (1) In the waste ternary battery material leachate (pH value = 2.0) 10m 3 adding 300 kg of wet slag of the first impurity remover (slag produced by the second stage copper removal of the previous batch, including the following components: copper sulfide, nickel sulfide, cobalt sulfide, ferric hydroxide and aluminum hydroxide, wherein the total mass percentage of nickel sulfide and cobalt sulfide is 75.4%) to carry out the first stage copper removal, controlling the reaction temperature to 80° C. and the reaction time to 4 h to obtain copper slag and a solution after the first copper removal, wherein the copper slag is washed with water 10 times its mass, the washing water after washing is used as a solvent for the mixed solution of soda ash and sodium sulfide in the deep impurity removal process, and the washed copper slag is used for further recovery of copper;

[0060] (2) adding 550 kg of wet slag of the second impurity remover (the slag produced by the previous batch of deep impurity removal, including copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide, wherein the total mass percentage of nickel sulfide and cobalt sulfide is 86%, and the total mass percentage of nickel hydroxide and cobalt hydroxide is 7.5%) to the solution after the first copper removal, and performing two-stage copper removal, controlling the reaction temperature to 80° C. and the reaction time to 4 h, to obtain slag and the solution after the second copper removal, wherein the slag (including copper sulfide, nickel sulfide, cobalt sulfide, ferric hydroxide and aluminum hydroxide, wherein the total mass percentage of nickel sulfide and cobalt hydroxide is 77.3%) is used as the impurity remover for the next batch of one-stage copper removal, i.e., the first impurity remover for the next batch of one-stage copper removal;

[0061] (3) After the second copper removal, a 30 wt% soda ash solution is added to the solution to remove iron and aluminum, and the pH value is adjusted to 4.5 to remove iron and aluminum. The reaction temperature is controlled to 85 ° C. and the reaction time is 4 h to obtain iron-aluminum slag and a solution after copper and iron-aluminum removal. The iron-aluminum slag is washed in a three-stage countercurrent manner and washed with water 10 times its mass. The washing water after washing is added to the next batch of waste lithium battery leachate to remove copper in the next batch. The washed iron-aluminum slag (the total amount of Ni, Co and Mn is <1.5 wt%) is used as general solid waste to make ceramsite;

[0062] (4) Add 1m 3 Mixed solution of soda ash and sodium sulfide (soda ash content 50kg / m 3 , sodium sulfide content 70kg / m 3) for deep impurity removal, controlling the reaction temperature to 85° C., the reaction time to 2 h, and the reaction endpoint pH to 6.5 to obtain a slag and a solution after deep impurity removal, wherein the slag (comprising copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide, with a total mass percentage of nickel sulfide and cobalt sulfide being 85.2% and a total mass percentage of nickel hydroxide and cobalt hydroxide being 6.7%) is used as an impurity remover for the next batch of second-stage copper removal, i.e., the second impurity remover for the next batch of second-stage copper removal; and the solution after deep impurity removal is used for further recovery of nickel, cobalt, manganese and lithium.

[0063] Table 3 Test data of impurity removal process of Example 3

[0064]

[0065] Example 4

[0066] This embodiment provides a method for removing impurities from waste lithium battery leachate, comprising the following steps:

[0067] (1) In the waste ternary battery material leachate (pH value = 1.0) 10m 3 1200 kg of wet slag with the first impurity remover (slag produced by the second-stage copper removal of the previous batch, including copper sulfide, nickel sulfide, cobalt sulfide, ferric hydroxide and aluminum hydroxide, wherein the total mass percentage of nickel sulfide and cobalt sulfide is 72.3%) is added to the reaction mixture for first-stage copper removal, the reaction temperature is controlled at 50° C., the reaction time is 5 h, and copper slag and a solution after the first copper removal are obtained, wherein the copper slag is washed with water 10 times its mass, the washing water after washing is used as a solvent for the mixed solution of soda ash and sodium sulfide in the deep impurity removal process, and the washed copper slag is used for further copper recovery;

[0068] (2) adding 500 kg of wet slag of the second impurity remover (the slag produced by the previous batch of deep impurity removal, including copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide, wherein the total mass percentage of nickel sulfide and cobalt sulfide is 83.9%, and the total mass percentage of nickel hydroxide and cobalt hydroxide is 8.6%) to the solution after the first copper removal, and performing two-stage copper removal, controlling the reaction temperature to 50° C. and the reaction time to 5 h, to obtain slag and the solution after the second copper removal, wherein the slag (including copper sulfide, nickel sulfide, cobalt sulfide, ferric hydroxide and aluminum hydroxide, wherein the total mass percentage of nickel sulfide and cobalt hydroxide is 74.2%) is used as the impurity remover for the next batch of one-stage copper removal, i.e., the first impurity remover for the next batch of one-stage copper removal;

[0069] (3) After the second copper removal, a 30 wt% soda ash solution is added to the solution to remove iron and aluminum, and the pH value is adjusted to 4.5 to remove iron and aluminum. The reaction temperature is controlled at 80° C. and the reaction time is 5 h to obtain iron-aluminum slag and a solution after copper and iron-aluminum removal. The iron-aluminum slag is washed in a three-stage countercurrent manner and washed with water 10 times its mass. The washed water is added to the next batch of waste lithium battery leachate to remove copper in the next batch. The washed iron-aluminum slag (the total amount of Ni, Co and Mn is <1.5 wt%) is used as general solid waste to make ceramsite.

[0070] (4) Add 1m 3 Mixed solution of soda ash and sodium sulfide (soda ash content 50kg / m 3 , sodium sulfide content 70kg / m 3 ) for deep impurity removal, controlling the reaction temperature to 70° C., the reaction time to 3 h, and the reaction endpoint pH to 6.0 to obtain a slag and a solution after deep impurity removal, wherein the slag (comprising copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide, with a total mass percentage of nickel sulfide and cobalt sulfide being 82.3%, and a total mass percentage of nickel hydroxide and cobalt hydroxide being 12.5%) is used as an impurity remover for the next batch of second-stage copper removal, i.e., the second impurity remover for the next batch of second-stage copper removal; and the solution after deep impurity removal is used for further recovery of nickel, cobalt, manganese and lithium.

[0071] Table 4 Example 4 impurity removal process test data

[0072]

[0073] Example 5

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

[0075] (1) In the waste ternary battery material leachate (pH value = 1.0) 10m 3 adding 300 kg of wet slag of a first impurity remover (prepared by adding alkali solution and sodium sulfide to a low-copper, iron, and aluminum lithium battery material leachate, including copper sulfide, nickel sulfide, cobalt sulfide, ferric hydroxide, and aluminum hydroxide, wherein the total mass percentage of nickel sulfide and cobalt sulfide is 76%) to perform a first stage of copper removal, controlling the reaction temperature at 90° C. and the reaction time for 1 hour to obtain copper slag and a solution after the first copper removal, wherein the copper slag is washed with water 10 times its mass, the washing water after washing is used as a solvent for a mixed solution of soda ash and sodium sulfide in a deep impurity removal process, and the washed copper slag is used for further copper recovery;

[0076] (2) adding 350 kg of wet slag of the second impurity remover (prepared by adding alkali solution and sodium sulfide to the leaching solution of low-copper, iron, and aluminum lithium battery materials, including copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide, wherein the total mass percentage of nickel sulfide and cobalt sulfide is 87.1%, and the total mass percentage of nickel hydroxide and cobalt hydroxide is 12.4%) to the solution after the first copper removal, and performing two-stage copper removal, controlling the reaction temperature to 90° C. and the reaction time to 1 hour, to obtain slag and the solution after the second copper removal, wherein the slag (including copper sulfide, nickel sulfide, cobalt sulfide, iron hydroxide and aluminum hydroxide, wherein the total mass percentage of nickel sulfide and cobalt hydroxide is 74.1%) is used as the impurity remover for the next batch of one-stage copper removal, i.e., the first impurity remover for the next batch of one-stage copper removal;

[0077] (3) After the second copper removal, a 30 wt% soda ash solution is added to the solution to remove iron and aluminum, and the pH value is adjusted to 4.0 to remove iron and aluminum. The reaction temperature is controlled at 95° C. and the reaction time is 1 h to obtain iron-aluminum slag and a solution after copper and iron-aluminum removal. The iron-aluminum slag is washed in a three-stage countercurrent manner and washed with water 10 times its mass. The washed water is added to the next batch of waste lithium battery leachate to remove copper in the next batch. The washed iron-aluminum slag (the total amount of Ni, Co and Mn is <1.5 wt%) is used as general solid waste to make ceramsite.

[0078] (4) Add 1m 3 Mixed solution of soda ash and sodium sulfide (soda ash content 50kg / m 3 , sodium sulfide content 70kg / m 3 ) for deep impurity removal, controlling the reaction temperature to 90° C., the reaction time to 1 hour, and the reaction endpoint pH to 6.5, to obtain a slag and a solution after deep impurity removal, wherein the slag (comprising the following components: copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide, and cobalt hydroxide, with the total mass percentage of nickel sulfide and cobalt sulfide being 87.4%, and the total mass percentage of nickel hydroxide and cobalt hydroxide being 7.7%) is used as an impurity remover for the next batch of second-stage copper removal, i.e., the second impurity remover for the next batch of second-stage copper removal; and the solution after deep impurity removal is used for further recovery of nickel, cobalt, manganese, and lithium;

[0079] (5) Process one more batch.

[0080] Table 5 Example 5 impurity removal process test data

[0081]

[0082]

[0083] Comparative Example 1

[0084] This comparative example provides a method for removing impurities from waste lithium battery leachate, comprising the following steps:

[0085] (1) In the waste ternary battery material leachate (pH value = 1.0) 10m 3 80 kg of iron powder was added to remove copper, the reaction temperature was controlled at 50 ° C, the reaction time was 4 h, and sponge copper slag and copper-removed liquid were obtained, wherein the copper slag was washed with water 10 times its mass;

[0086] (2) Add 180 L of 27.5% hydrogen peroxide to the copper-removed solution, control the temperature at 50°C, and react for 2 hours;

[0087] (3) Add 2.5m 3 30wt% soda ash solution is used to remove iron and aluminum, and the pH value is adjusted to 4.0-4.5 for iron and aluminum removal. The reaction temperature is controlled at 95°C and the reaction time is 1 hour to obtain iron and aluminum slag and a solution after copper and iron and aluminum removal. The iron and aluminum slag is washed in a three-stage countercurrent manner and washed with water 10 times its mass. The washing water is added to the next batch of waste lithium battery leachate to remove copper in the next batch. The washed iron and aluminum slag is used as general solid waste to make ceramsite;

[0088] (4) Add 1m 3 Mixed solution of soda ash and sodium sulfide (soda ash content 50kg / m 3 , sodium sulfide content 20kg / m 3 ) for deep impurity removal, controlling the reaction temperature at 90°C, the reaction time for 1 hour, the pH value at the reaction end point to be 6.5, to obtain slag and a solution after deep impurity removal, wherein the slag is 200 kg.

[0089] Table 6 Comparative Example 1 impurity removal process test data

[0090]

[0091] Compared with the present invention, the above comparative example 1 has the following disadvantages:

[0092] ① After adding iron powder to replace copper, ferrous iron accounts for more than 90% of the total iron in the liquid after replacement, and hydrogen is also produced, which poses a safety risk;

[0093] ② Ferrous iron needs to be oxidized in advance before iron removal, and a large amount of hydrogen peroxide is required;

[0094] ③ The iron content in the oxidized liquid is 200% higher than that in the leaching liquid, resulting in an increase of not less than 100% in the iron-aluminum slag content during the iron-aluminum removal process. This results in a large amount of iron-aluminum slag, a long operation cycle, and increased washing water consumption.

[0095] ④ The amount of alkali solution increased by 2.5 times, and the cost of auxiliary materials is high;

[0096] ⑤ After washing, the amount of nickel, cobalt and other precious metals carried away from the iron-aluminum slag increased significantly compared to Example 2, and this part of the precious metals could not be effectively recovered;

[0097] ⑥ After deep impurity removal, the concentration of nickel, cobalt and other cobalt metals in the liquid further decreases, and the deep impurity removal slag is returned to the leaching process for recovery. Part of the nickel and cobalt will be lost with the leaching slag.

[0098] Comparative Example 2

[0099] This comparative example provides a method for removing impurities from waste lithium battery leachate, comprising the following steps:

[0100] (1) In the waste ternary battery material leachate (pH value = 1.5) 10m 3 adding 700 kg of wet slag (comprising copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide, wherein the total mass percentage of nickel sulfide and cobalt sulfide is 82.4% and the total mass content of nickel hydroxide and cobalt hydroxide is 6.8%) of the second impurity remover to remove copper, controlling the reaction temperature to 80° C. and the reaction time to 4 h to obtain copper slag and a solution after copper removal, wherein the copper slag is washed with water 10 times its mass, and the washed copper slag is used for further recovery of copper;

[0101] (2) adding 30 wt% soda ash solution to the copper-removed solution to remove iron and aluminum, adjusting the pH value to 4.5 to remove iron and aluminum, controlling the reaction temperature to 85° C., and the reaction time to 4 h to obtain iron-aluminum slag and a solution after copper, iron, and aluminum removal;

[0102] (3) Add 1m 3 Mixed solution of soda ash and sodium sulfide (soda ash content 50kg / m 3 , sodium sulfide content 70kg / m 3 ) for deep impurity removal, controlling the reaction temperature at 85°C, the reaction time for 2h, and the reaction end point pH value at 6.0 to obtain slag and a solution after deep impurity removal, which is used to further recover nickel, cobalt, manganese and lithium.

[0103] Table 7 Comparative Example 2 impurity removal process test data

[0104]

[0105] Compared with Example 1, Comparative Example 2 uses the second impurity remover as the impurity remover for the first copper removal step. The Ni content in the resulting copper slag is relatively high, and the loss of valuable metals is relatively high. This is because an excess of impurity remover needs to be added to achieve more thorough copper removal, resulting in a high nickel content and a low Cu / Ni (mass ratio) in the copper slag after copper removal. The present invention uses two-stage impurity removal. First, an excess of a larger amount of impurity remover is added in the second copper removal step to more thoroughly remove copper. Then, the process returns to the first copper removal step to remove most of the copper in the leachate. This ensures that the nickel in the first impurity remover added in the first step replaces copper with high efficiency, and the Cu / Ni (mass ratio) in the final copper slag is also high.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for removing impurities from waste lithium battery leachate, characterized in that: The following steps are involved: A first impurity remover is added to the waste lithium battery leachate to perform a first stage of copper removal to obtain copper slag and a first copper-removed solution; Adding a second impurity remover to the first copper-removed solution for two-stage copper removal to obtain a slag and a second copper-removed solution, wherein the obtained slag is used as a first impurity remover for impurity removal of the next batch of waste lithium battery leachate; adding alkali to the second copper-removed solution to adjust the pH value to 4.0-4.5 to precipitate iron and aluminum, thereby obtaining iron-aluminum slag and a solution after removing iron, aluminum and copper; Adding soda ash and sodium sulfide to the solution after removing iron, aluminum and copper for deep impurity removal to obtain a slag and a solution after deep impurity removal, and using the obtained slag as a second impurity remover for removing impurities in the next batch of waste lithium battery leachate; Using the deeply impurity-removed solution to recover nickel, cobalt, manganese and lithium; Wherein, the first impurity remover comprises copper sulfide, nickel sulfide, cobalt sulfide, ferric hydroxide and aluminum hydroxide, and the total mass percentage of nickel sulfide and cobalt sulfide in the first impurity remover is greater than 70%; The second impurity remover comprises copper sulfide, nickel sulfide, cobalt sulfide, nickel hydroxide and cobalt hydroxide, wherein the total mass percentage of nickel sulfide and cobalt sulfide in the second impurity remover is more than 80%, and the total mass percentage of nickel hydroxide and cobalt hydroxide is 5-15%; In the deep impurity removal process, the added soda ash and sodium sulfide are a mixed solution of soda ash and sodium sulfide, in which the mass percentage of soda ash is 5-20% and the mass percentage of sodium sulfide is 5-20%.

2. The method for removing impurities from waste lithium battery leachate according to claim 1, wherein: The wet basis mass of the first impurity remover is 3-20% of the amount of the waste lithium battery leachate; the reaction temperature in the copper removal process is 50-90° C., and the reaction time is 1-5 hours.

3. The method for removing impurities from waste lithium battery leachate according to claim 1, wherein: The added wet basis mass of the second impurity remover is 3.5-40% of the amount of the waste lithium battery leachate; the reaction temperature in the second stage copper removal process is 50-90° C., and the reaction time is 1-5 hours.

4. The method for removing impurities from waste lithium battery leachate according to claim 1, wherein: In the second copper-removed solution, alkali is added to adjust the pH to precipitate iron and aluminum. The reaction temperature is 80-95° C. and the reaction time is 1-5 hours.

5. The method for removing impurities from waste lithium battery leachate according to claim 1, wherein: In the step of adding alkali to the second copper-removed solution to adjust the pH to precipitate iron and aluminum, the alkali used is at least one of soda ash and sodium hydroxide.

6. The method for removing impurities from waste lithium battery leachate according to claim 1, wherein: In the deep impurity removal process, the reaction temperature is 70-90° C., the reaction time is 1-3 hours, and the pH value at the reaction end point is 6.0-6.

5.

7. The method for removing impurities from waste lithium battery leachate according to claim 1, wherein: The pH value of the waste lithium battery leachate is 1.0-2.0, and the leachate includes the following components: Ni 35-65g / L, Co 15-35g / L, Mn 10-25g / L, Cu 0-10g / L and greater than 0, Fe 0-10g / L and greater than 0, Al 0-10g / L and greater than 0; the Cu content in the first solution after copper removal is less than 1g / L, and the mass of Cu contained in the first copper slag after washing with water is greater than 15 / the mass of Ni contained; the Cu content in the second solution after copper removal is less than 2mg / L; and the Cu content in the solution after deep impurity removal is less than 0.5mg / L, Fe is less than 3mg / L, and Al is less than 1mg / L.

8. The method for removing impurities from waste lithium battery leachate according to claim 1, wherein: At least one of the conditions (a) and (b) is met: (a) the copper slag is cleaned with water, and solid-liquid separation is performed to obtain the cleaned copper slag and copper slag wash water, the cleaned copper slag is used to recover copper, and the copper slag wash water is used as a solvent for a mixed solution of soda ash and sodium sulfide used in a deep impurity removal process; (b) washing the iron-aluminum slag with water, separating the solid and the liquid, obtaining washed iron-aluminum slag and iron-aluminum slag washing water, and adding the obtained iron-aluminum slag washing water to the next batch of waste lithium battery leachate for impurity removal.

9. The method for removing impurities from waste lithium battery leachate according to claim 8, wherein: When the copper slag is washed with water, the mass of the water used is 2-10 times the wet mass of the copper slag; when the iron-aluminum slag is washed with water, the cleaning method used is three-stage countercurrent washing, and the mass of the water used is 2-10 times the wet mass of the iron-aluminum slag.

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