WO2024066175A1

WO2024066175A1 - Method for removing carbonate radicals from lithium precipitation mother liquor

Info

Publication number: WO2024066175A1
Application number: PCT/CN2023/077161
Authority: WO
Inventors: 苗耀文; 李长东; 乔延超; 李波; 陈若葵; 阮丁山
Original assignee: 广东邦普循环科技有限公司; 湖南邦普循环科技有限公司
Priority date: 2022-09-30
Filing date: 2023-02-20
Publication date: 2024-04-04
Also published as: CN115571926B; CN115571926A

Abstract

The present application provides a method for removing carbonate radicals from a lithium precipitation mother liquor. The method comprises: mixing a lithium precipitation mother liquor with nickel-cobalt-manganese wastewater for reaction, and removing carbonate radicals from the lithium precipitation mother liquor to prepare nickel-cobalt-manganese carbonate slag. According to the present application, in the process of removing the carbonate radicals from the lithium precipitation mother liquor, the pH value does not need to be adjusted, the use of an acid liquor or an alkali liquor is avoided, and the content of the carbonate radicals in the lithium precipitation mother liquor can be greatly reduced, so that the carbonate radicals in the lithium precipitation mother liquor are efficiently and simply removed at low cost. Moreover, the nickel-cobalt-manganese carbonate slag is prepared while the carbonate radicals are removed, and the nickel-cobalt-manganese carbonate slag can be used for preparing a ternary positive electrode material, so that the effect of recycling nickel, cobalt and manganese from the nickel-cobalt-manganese wastewater is achieved.

Description

A method for removing carbonate from lithium precipitation mother liquor

Technical Field

The present application belongs to the field of environmental protection technology and relates to a method for removing carbonate from lithium precipitation mother liquor.

Background technique

With the increasing shortage of traditional energy sources such as oil, the development of new energy sources has received more and more attention, especially the demand for lithium batteries is growing rapidly. Lithium carbonate is an important component of lithium batteries. In industry, lithium is generally precipitated with excessive sodium carbonate. After solid-liquid separation, solid lithium carbonate and lithium precipitation mother liquor are obtained. Due to the efficiency of lithium precipitation, the lithium precipitation mother liquor still contains a large amount of lithium ions. If this part of the lithium precipitation mother liquor is directly discharged, it will cause a large amount of lithium loss. Therefore, the lithium precipitation mother liquor is generally evaporated and concentrated for lithium precipitation again. The lithium precipitation mother liquor needs to remove carbonate before entering the evaporation system. At present, the industry first uses sulfuric acid to treat it to remove carbonate in the lithium precipitation mother liquor, and then uses liquid alkali to adjust the lithium precipitation mother liquor to neutral before entering the evaporation and concentration system.

For example, CN113912090A discloses a method for recovering high-purity lithium carbonate by causticizing, freezing and removing mirabilite from lithium precipitate mother liquor, wherein a certain amount of calcium oxide is added to the lithium precipitate mother liquor for causticizing and stirring, the solution pH is adjusted to 12-14, the reaction is carried out for 2.0-8.5 hours, the temperature is 30-60°C, and the calcium carbonate precipitate and causticized solution are obtained after filtration, and the carbonate in the lithium precipitate mother liquor is removed. For example, CN112158865A discloses a method for recovering and recycling lithium in lithium precipitate mother liquor, wherein the method for removing lithium carbonate is to add hydrochloric acid to the lithium precipitate mother liquor, control the pH value of the mother liquor within the range of 4-7, the molar amount of chloride ions added to the hydrochloric acid is 1.5-3.0 times the molar amount of carbonate ions in the solution, and the lithium precipitate mother liquor and the hydrochloric acid are mixed and stirred in a buffer tank in turn, and heated while stirring, so that the carbon dioxide generated in the solution is discharged and the carbonate is removed. For example, CN105347364A discloses a closed-loop recovery method for lithium precipitation mother liquor in lithium carbonate production, wherein the method for removing carbonate ions is as follows: hydrochloric acid is added to the lithium precipitation mother liquor, the pH value of the mother liquor is controlled within the range of 3.5-6.5, the molar amount of chloride ions added to the hydrochloric acid is 1.1-3.0 times the molar amount of carbonate ions in the solution, and the carbon dioxide generated in the solution is discharged from the system as soon as possible by stirring, heating, natural evaporation, and vacuuming to achieve the removal of carbonate ions. the goal of.

However, the above-mentioned methods for removing carbonate ions are relatively complicated and require the addition of a pH regulator to adjust the pH value of the mother liquor, which is time-consuming and not conducive to expanding production.

Based on this, in order to avoid the use of acid and alkali solutions, it is necessary to apply for an efficient and green method for removing carbonate from lithium precipitation mother liquor.

Summary of the invention

The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

In view of the above-mentioned problems existing in the prior art, the purpose of the present application is to provide a method for removing carbonate from a lithium precipitation mother liquor. In the present application, the lithium precipitation mother liquor and nickel-cobalt-manganese wastewater are mixed and reacted to remove carbonate from the lithium precipitation mother liquor to prepare nickel-cobalt-manganese carbonate slag.

To achieve the above purpose, this application adopts the following technical solutions:

In a first aspect, the present application provides a method for removing carbonate from a lithium precipitation mother liquor, the method comprising the following steps: mixing the lithium precipitation mother liquor and nickel-cobalt-manganese wastewater and reacting them to remove carbonate from the lithium precipitation mother liquor and prepare nickel-cobalt-manganese carbonate slag.

In the present application, nickel-cobalt-manganese wastewater is used to remove carbonate in the lithium precipitation mother liquor. On the one hand, there is no need to adjust the pH value of the lithium precipitation mother liquor during the removal of carbonate, thereby avoiding the use of acid and alkali solutions. On the other hand, while removing carbonate in the lithium precipitation mother liquor, nickel-cobalt-manganese carbonate slag is also generated, which can be used for the preparation of ternary positive electrode materials.

In the present application, the use of aluminum salt or calcium oxide alone cannot effectively remove the carbonate in the lithium precipitation mother liquor, and more aluminum ions and calcium ions will be introduced after the carbonate is removed, so that the primary filtrate after the removal of carbonate from the lithium precipitation mother liquor needs to be further removed of impurity ions before it can be recycled.

In the present application, the equation for the reaction of the lithium precipitation mother liquor and the nickel-cobalt-manganese wastewater is as follows:

xNi ²⁺ +yCo ²⁺ +(1-xy)Mn ²⁺ +CO ₃ ^2- =Ni _x Co _y Mn _1-xy CO ₃ ↓, wherein 1＞x＞0, 1＞y＞0, 1＞1-xy＞0, for example, x is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, for example, y is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, for example, 1-xy is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9.

In the present application, the preparation method of the ternary positive electrode material is not limited. Exemplarily, the preparation method of the ternary positive electrode material includes: mixing nickel cobalt manganese carbonate slag and a lithium source and sintering them to prepare the ternary positive electrode material, wherein the lithium source includes but is not limited to lithium carbonate, lithium hydroxide or lithium acetate.

In the present application, the lithium precipitation mother liquor refers to the mother liquor discharged during the production of lithium carbonate. The main ions in the lithium precipitation mother liquor are Li ⁺ , and the main impurity is CO ₃ ^2- .

In the present application, the nickel-cobalt-manganese wastewater refers to the wastewater generated after recovering lithium and nickel-cobalt-manganese from retired ternary lithium batteries. The main ions in the nickel-cobalt-manganese wastewater are nickel ions, cobalt ions and manganese ions.

Optionally, the molar ratio of the total content of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese wastewater to the carbonate content in the lithium precipitation mother liquor is (0.7-1.5): 1, for example, "0.7-1.5" can be 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5, preferably (0.8-1.4): 1. When the molar ratio of the total content of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese wastewater to the carbonate content in the lithium precipitation mother liquor is less than 0.7, the carbonate in the lithium precipitation mother liquor cannot be effectively removed. When the total content of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese wastewater and the carbonate content in the lithium precipitation mother liquor are in a suitable ratio, the effect of better removing carbonate in the lithium precipitation mother liquor can be achieved, and the introduction of excess impurity ions can be avoided at the same time.

Optionally, the reaction temperature is 50-150°C, for example 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C.

Optionally, the reaction time is 1-5 h, such as 1 h, 2 h, 3 h, 4 h or 5 h.

Optionally, after the reaction, the liquid and solid in the reaction system are separated once to obtain a primary filtrate and nickel cobalt manganese carbonate slag.

The present application does not limit the method of primary separation. By way of example, the method of primary separation includes but is not limited to pressure filtration or vacuum filtration.

Optionally, the nickel cobalt manganese carbonate slag is subjected to pulping and water washing, and the purpose of pulping and water washing is to wash away residual lithium ions and carbonate in the nickel cobalt manganese carbonate slag.

Optionally, the pulping water washing is followed by secondary separation to obtain a secondary filtrate and nickel, cobalt and manganese carbonate washing residue.

The present application does not limit the method of secondary separation. By way of example, the method of secondary separation includes but is not limited to pressure filtration or vacuum filtration.

Optionally, the secondary filtrate is returned to the lithium precipitation mother liquor for reuse.

The secondary filtrate contains lithium ions and carbonate ions. The secondary filtrate is returned to the lithium precipitation mother liquor for reuse, which can effectively avoid the loss of lithium.

Optionally, the secondary filtrate is evaporated and concentrated before being returned to the lithium precipitation mother liquor.

Optionally, the pulping and washing comprises: mixing the nickel cobalt manganese carbonate slag with water to form a nickel cobalt manganese carbonate slurry.

Optionally, the solid-liquid ratio of the nickel cobalt manganese carbonate slag and water is 1:(3-5), for example, "3-5" can be 3, 4 or 5.

In the present application, the solid-to-liquid ratio refers to the ratio of the mass of the nickel-cobalt-manganese carbonate slag to the mass of water.

As a preferred technical solution of the method described in the present application, the lithium precipitation mother liquor and aluminum salt are pre-reacted before the lithium precipitation mother liquor and nickel-cobalt-manganese wastewater are mixed and reacted.

In the present application, if the lithium precipitation mother liquor and aluminum salt are not pre-reacted and the lithium precipitation mother liquor, aluminum salt and nickel-cobalt-manganese wastewater are directly mixed at the same time, more aluminum hydroxide will be generated preferentially, affecting the recovery of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese wastewater; if the lithium precipitation mother liquor and nickel-cobalt-manganese wastewater are pre-reacted first and then the aluminum salt is added to react, part of the nickel-cobalt-manganese carbonate slag will dissolve to generate aluminum hydroxide, which is also not conducive to the recovery of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese wastewater.

In the present application, the lithium precipitation mother solution and the aluminum salt are pre-reacted in advance. The aluminum ions in the aluminum salt have the function of removing carbonate ions on the one hand, and on the other hand, they can be doped into the nickel cobalt manganese carbonate slag or coated on the surface of the nickel cobalt manganese carbonate slag as doping elements or coating elements, thereby improving the electrochemical performance of the prepared positive electrode material. In addition, the _CO2 generated during the reaction of the lithium precipitation mother solution and the aluminum salt can be recovered and used in the process of carbonizing the lithium precipitation after recovery.

Optionally, the aluminum salt includes at least one of aluminum sulfate and aluminum chloride.

Optionally, the molar ratio of aluminum ions in the aluminum salt to carbonate in the lithium precipitation mother solution is (0.05-0.15):1, for example, "0.05-0.15" can be 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14 or 0.15, preferably (0.08-0.12):1.

In the present application, when the amount of aluminum salt added is too much or too little, the electrochemical properties of the prepared positive electrode material will be affected. Only when the amount of aluminum salt added is moderate can the performance of the prepared positive electrode material reach the optimal level.

Optionally, the temperature of the pre-reaction is 50-150°C, for example 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C.

Optionally, the pre-reaction time is 0.5-3 h, such as 0.5 h, 1 h, 2 h, 2.5 h or 3 h.

Compared with the prior art, this application has the following beneficial effects:

(1) The present application does not require pH adjustment during the process of removing carbonate from the lithium precipitation mother liquor, thus avoiding the use of acid or alkali solution, and can significantly reduce the carbonate in the lithium precipitation mother liquor, thereby achieving efficient, simple and low-cost removal of carbonate from the lithium precipitation mother liquor.

(2) The method for removing carbonate in the present application not only removes carbonate but also prepares nickel cobalt manganese carbonate slag. The nickel cobalt manganese carbonate slag can be used for the preparation of ternary positive electrode materials, thereby achieving the effect of recovering nickel cobalt manganese from nickel cobalt manganese wastewater. The method in the present application can be applied to battery recycling, hydrometallurgy and other fields, and has a wide range of applicability.

(3) Further, in the present application, in the process of removing carbonate from the lithium precipitation mother solution, the lithium precipitation mother solution is preliminarily The aluminum salt is pre-reacted. The aluminum ions in the aluminum salt can remove carbonate ions on the one hand, and can be doped into the nickel cobalt manganese carbonate slag or coated on the surface of the nickel cobalt manganese carbonate slag as doping elements or coating elements on the surface of the nickel cobalt manganese carbonate slag on the other hand, thereby improving the electrochemical performance of the prepared positive electrode material. In addition, the _CO2 generated during the reaction of the lithium precipitation mother liquor and the aluminum salt can be recovered and used in the process of carbonization of lithium precipitation.

Other aspects will be apparent upon reading and understanding the drawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are used to provide further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

FIG. 1 is a flow chart of removing carbonate from lithium precipitation mother solution in an embodiment of the present application.

Detailed ways

The technical solution of the present application is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only to help understand the present application and should not be regarded as specific limitations of the present application.

In one embodiment, the present application provides a method for removing carbonate from a lithium precipitation mother liquor, and the flow chart is shown in Figure 1, comprising the following steps: reacting the lithium precipitation mother liquor and nickel-cobalt-manganese wastewater, performing a primary separation after the reaction to obtain a nickel-cobalt-manganese carbonate slag and a primary filtrate, slurrying and washing the nickel-cobalt-manganese carbonate slag, and performing a secondary separation by filter pressing to obtain a nickel-cobalt-manganese carbonate washing slag and a secondary filtrate, and the secondary filtrate is returned to the original lithium precipitation mother liquor after evaporation and concentration, and the carbonate is removed again.

Example 1

This embodiment provides a method for removing carbonate from a lithium precipitation mother solution, comprising the following steps:

S1: 2L lithium precipitation mother liquor and 4.4L nickel-cobalt-manganese wastewater were measured, wherein the content of carbonate in the lithium precipitation mother liquor was 29.8g/L, the content of nickel ions in the nickel-cobalt-manganese wastewater was 4.48g/L, the content of cobalt ions was 4.50g/L, and the content of manganese ions was 4.20g/L;

S2: 2L lithium precipitation mother liquor and 4.4L nickel-cobalt-manganese wastewater were placed in a reaction tank and reacted at 80°C for 2h;

S3: Cooling the reacted solution to 25° C., separating the reacted liquid and solid by filter pressing, and obtaining 6.3 L of a primary filtrate containing nickel cobalt manganese carbonate slag and a carbonate content of 0.09 g/L;

S4: The nickel cobalt manganese carbonate slag is pulped, washed and filtered to remove the lithium ions entrained in the nickel cobalt manganese carbonate slag. The secondary filtrate obtained is evaporated and concentrated and returned to the lithium precipitation mother liquor to continue to remove carbonate ions. The solid-liquid ratio of the nickel cobalt manganese carbonate slag to water during the pulping and washing process is 1:3.

In this embodiment, it is calculated that the molar ratio of the total content of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese wastewater to the carbonate content in the lithium precipitation mother liquor is 1.02:1.

Example 2

S1: 2L lithium precipitation mother liquor and 8.5L nickel-cobalt-manganese wastewater were measured, wherein the content of carbonate in the lithium precipitation mother liquor was 25.6g/L, the content of nickel ions in the nickel-cobalt-manganese wastewater was 2.83g/L, the content of cobalt ions was 1.42g/L, and the content of manganese ions was 2.65g/L;

S2: Place 2L lithium precipitation mother liquor and 8.5L nickel-cobalt-manganese wastewater in a reaction tank and react at 120°C for 3h;

S3: Cooling the reacted solution to 25° C., separating the reacted liquid and solid by filter pressing, and obtaining 10.3 L of a primary filtrate containing nickel cobalt manganese carbonate slag and a carbonate content of 0.04 g/L;

In this embodiment, it is calculated that the molar ratio of the total content of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese wastewater to the carbonate content in the lithium precipitation mother liquor is 1.2:1.

Example 3

S1: 2L lithium precipitation mother liquor and 3.4L nickel-cobalt-manganese wastewater were measured, wherein the content of carbonate in the lithium precipitation mother liquor was 26.8g/L, the content of nickel ions in the nickel-cobalt-manganese wastewater was 6.84g/L, the content of cobalt ions was 2.75g/L, and the content of manganese ions was 3.84g/L;

S2: Add 2L lithium precipitation mother liquor and 16.8g aluminum sulfate into the reaction tank, pre-react at 80°C for 1h, then add 3.4L nickel-cobalt-manganese wastewater and react at 80°C for 2h;

S3: Cooling the reacted solution to 25° C., separating the reacted liquid and solid by filter pressing, and obtaining 5.3 L of primary filtrate with aluminum-doped or aluminum-coated nickel-cobalt-manganese carbonate slag and a carbonate content of 0.09 g/L;

S4: The aluminum-doped or aluminum-coated nickel cobalt manganese carbonate slag is pulped, washed and filtered to remove lithium ions entrained in the aluminum-doped or aluminum-coated nickel cobalt manganese carbonate slag, and the obtained secondary filtrate is evaporated and concentrated and returned to the lithium precipitation mother liquor to continue to remove carbonate ions, wherein the solid-liquid ratio of the aluminum-doped or aluminum-coated nickel cobalt manganese carbonate slag to water during the pulping and washing process is 1:3.

In this embodiment, it is calculated that the molar ratio of the total content of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese wastewater to the carbonate content in the lithium precipitation mother liquor is 0.89:1, and the molar ratio of aluminum ions to carbonate in the lithium precipitation mother liquor is 0.11:1.

Example 4

S1: 2L lithium precipitation mother liquor and 5L nickel-cobalt-manganese wastewater were measured, wherein the content of carbonate in the lithium precipitation mother liquor was 31.3g/L, the content of nickel ions in the nickel-cobalt-manganese wastewater was 6.12g/L, the content of cobalt ions was 3.69g/L, and the content of manganese ions was 3.44g/L;

S2: Add 2L lithium precipitation mother liquor and 16g aluminum sulfate into the reaction tank, pre-react at 120°C for 2h, then add 5L nickel-cobalt-manganese wastewater and react at 130°C for 2h;

S3: The reaction solution was cooled to 25°C and the reaction liquid and solid were separated by filter press. Second separation, to obtain aluminum-doped or aluminum-coated nickel-cobalt-manganese carbonate slag and 6.9 L of primary filtrate with a carbonate content of 0.06 g/L;

In this embodiment, it is calculated that the molar ratio of the total content of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese wastewater to the carbonate content in the lithium precipitation mother liquor is 1.1:1, and the molar ratio of aluminum ions to carbonate in the lithium precipitation mother liquor is 0.09:1.

Example 5

S2: Add 2L lithium precipitation mother liquor and 14.5g aluminum sulfate of aluminum chloride into the reaction tank, pre-react at 120°C for 2h, then add 4.8L nickel-cobalt-manganese wastewater and react at 100°C for 4h;

S3: Cooling the reacted solution to 25° C., separating the reacted liquid and solid by filter pressing, and obtaining 5.3 L of primary filtrate with aluminum-doped or aluminum-coated nickel-cobalt-manganese carbonate slag and a carbonate content of 0.08 g/L;

In this embodiment, it is calculated that the molar ratio of the total content of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese wastewater to the carbonate content in the lithium precipitation mother liquor is 0.89:1, and the molar ratio of aluminum ions to carbonate in the lithium precipitation mother liquor is 0.12:1.

Example 6

The only difference from Example 1 is that the amount of nickel-cobalt-manganese wastewater used is 6L. In this embodiment, it is calculated that the molar ratio of the total content of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese wastewater to the carbonate content in the lithium precipitation mother liquor is 1.4:1, and the volume of the primary filtrate is 7.9L.

Comparative Example 1

This comparative example provides a method for removing carbonate from a lithium precipitation mother solution, comprising the following steps:

S2: Add 2L lithium precipitation mother liquor, 16g aluminum sulfate and 5L nickel-cobalt-manganese wastewater into the reaction tank and react at 80°C for 2h;

S3: Cooling the reacted solution to 25° C., separating the reacted liquid and solid by filter pressing, and obtaining 6.9 L of a primary filtrate having a solid slag and a carbonate content of 0.08 g/L;

S4: The solid slag is pulped, washed and filtered to remove lithium ions entrained in the solid slag. The secondary filtrate obtained is evaporated and concentrated and returned to the lithium precipitation mother liquor to continue to remove carbonate ions. The solid-liquid ratio of the solid slag to water in the pulping and washing process is 1:3.

Comparative Example 2

The method for removing carbonate from lithium precipitation mother solution in this comparative example comprises the following steps:

S1: Measure 2L of lithium precipitation mother solution and weigh 55.6g of calcium oxide, wherein the content of carbonate in the lithium precipitation mother solution is 29.8g/L;

S2: Adjust the pH value of the solution to 12.2 and react at 80°C for 2h;

S2: Cooling the reacted solution to 25°C, separating the reacted liquid and solid by filter pressing, and obtaining 1.9L of filtrate containing calcium carbonate slag and carbonate content of 3.6g/L;

S4: The calcium carbonate slag is pulped, washed and filtered to remove the lithium ions entrained in the calcium carbonate slag. The secondary filtrate obtained is evaporated and concentrated and returned to the lithium precipitation mother liquor to continue to remove carbonate ions. The solid-liquid ratio of the calcium carbonate slag to water in the pulping and washing process is 1:3.

Performance testing:

The content of carbonate in the primary filtrate is detected by double indicator neutralization method; the content of metal ions in the primary filtrate is detected by atomic absorption spectrometry.

The contents of various ions in the primary filtrate after removing carbonate from the lithium precipitation mother liquor in Examples 1 to 6 and Comparative Examples 1 to 2 are shown in Table 1.

Table 1

The removal rate of CO ₃ ^2- is the ratio of the difference between the content of CO ₃ ^2- in the lithium precipitation mother liquor and the content of CO ₃ ^2- in the primary filtrate after removing carbonate to the content of CO ₃ ^2- in the lithium precipitation mother liquor.

analyze:

Table 1 is a statistical table of the content of each ion in the primary filtrate after removing carbonate in Examples 1 to 6 of the present application and Comparative Examples 1 to 2. It can be seen from Examples 1 to 6 that the use of nickel-cobalt-manganese wastewater to react with the lithium precipitation mother liquor or the use of aluminum salt and the lithium precipitation mother liquor for pre-reaction and then the reaction with the nickel-cobalt-manganese wastewater can significantly reduce the content of carbonate in the lithium precipitation mother liquor, and when the molar ratio of the total content of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese wastewater to the carbonate content in the lithium precipitation mother liquor is moderate, it can ensure the removal effect of carbonate and avoid the introduction of too many impurity ions; when the total content of nickel ions, manganese ions and cobalt ions in the nickel-cobalt-manganese wastewater is relatively high, although the carbonate in the lithium precipitation mother liquor can also be removed well, more nickel ions, manganese ions and cobalt ions will be introduced into the primary filtrate.

It can be seen from the data of Comparative Example 1 that if the lithium precipitation mother liquor, aluminum salt and nickel-cobalt-manganese wastewater are mixed together, although the carbonate ions in the lithium precipitation mother liquor can be removed, due to the mutual influence between aluminum ions and nickel ions, manganese ions and cobalt ions, a relatively large number of impurity ions remain in the primary filtrate, and aluminum ions also affect the formation of nickel-cobalt-manganese carbonate slag.

It can be seen from the data of Comparative Example 2 that the use of calcium oxide alone cannot effectively remove the carbonate in the lithium precipitation mother liquor, and a relatively large amount of calcium ions will remain in the obtained primary filtrate.

The applicant declares that the present application illustrates the detailed method of the present application through the above-mentioned embodiments, but the present application is not limited to the above-mentioned detailed method, that is, it does not mean that the present application must rely on the above-mentioned detailed method to be implemented. Technical personnel in the relevant technical field should understand that any improvement to the present application, equivalent replacement of raw materials of the products of the present application, addition of auxiliary ingredients, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present application.

Claims

A method for removing carbonate from lithium precipitation mother liquor, wherein the method comprises the following steps:

The lithium precipitation mother liquor and the nickel-cobalt-manganese wastewater are mixed and reacted to remove the carbonate ions in the lithium precipitation mother liquor to prepare the nickel-cobalt-manganese carbonate slag.
The method according to claim 1, wherein the molar ratio of the total content of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese wastewater to the carbonate content in the lithium precipitation mother liquor is (0.7-1.5):1, preferably (0.8-1.4):1.
The method according to claim 1 or 2, wherein the reaction temperature is 50-150°C;

Optionally, the reaction time is 1-5h.
The method according to any one of claims 1 to 3, wherein after the reaction, the liquid and solid in the reaction system are separated once to obtain a primary filtrate and nickel cobalt manganese carbonate slag;

Optionally, the nickel-cobalt-manganese carbonate slag is pulped and washed.
The method according to claim 4, wherein the pulping is washed with water and then subjected to secondary separation to obtain secondary filtrate and nickel, cobalt and manganese carbonate washing residue;

Optionally, the secondary filtrate is returned to the lithium precipitation mother liquor for reuse;

Optionally, the secondary filtrate is evaporated and concentrated before being returned to the lithium precipitation mother liquor.
The method according to claim 4 or 5, wherein the pulping and washing comprises: mixing the nickel cobalt manganese carbonate slag with water to form a nickel cobalt manganese carbonate slurry;

Optionally, the solid-to-liquid ratio of the nickel-cobalt-manganese carbonate slag to water is 1:(3-5).
The method according to any one of claims 1 to 6, wherein the lithium precipitation mother liquor and the aluminum salt are pre-reacted before the lithium precipitation mother liquor and the nickel-cobalt-manganese wastewater are mixed and reacted.
The method according to claim 7, wherein the aluminum salt comprises at least one of aluminum sulfate and aluminum chloride.
The method according to claim 7 or 8, wherein the aluminum ions in the aluminum salt and the precipitate The molar ratio of carbonate in the lithium mother solution is (0.05-0.15):1, preferably (0.08-0.12):1.
The method according to any one of claims 7 to 9, wherein the temperature of the pre-reaction is 50 to 150° C.;

Optionally, the pre-reaction time is 0.5-3h.