阅读说明：本技术 一种去除中间物料硫酸锂溶液中钙离子的氢氧化锂母液及其方法 (Lithium hydroxide mother liquor for removing calcium ions in intermediate material lithium sulfate solution and method thereof ) 是由 雷浪 孟岩 王文洪 高青健 邓勇 邓雅杰 于 2020-06-16 设计创作，主要内容包括：本发明公开了一种去除中间物料硫酸锂溶液中钙离子的氢氧化锂母液及其方法,所述氢氧化锂母液按质量百分比包括以下组分,一水氢氧化锂8％-10％,氢氧化钠1％-2％,硫酸锂3％-5％,硫酸钠2％-3％,其余为水,具体操作方法为使用氢氧化锂母液调节硫酸锂溶液的PH值至11-12,氢氧化锂母液中的硫酸根离子与硫酸锂溶液中的钙离子产生硫酸钙沉淀,滤除硫酸钙沉淀。本技术方案采用氢氧化锂母液作为去除硫酸锂溶液中钙离子的去除剂,其组成母液混合液的组分及其配比,经过实际的工艺验证,对比,在去除钙离子含量上具有良好的效果,且不会给工艺增加额外的操作程序。(The invention discloses a lithium hydroxide mother liquor for removing calcium ions in an intermediate material lithium sulfate solution and a method thereof, wherein the lithium hydroxide mother liquor comprises, by mass, 8% -10% of lithium hydroxide monohydrate, 1% -2% of sodium hydroxide, 3% -5% of lithium sulfate, 2% -3% of sodium sulfate and the balance of water, and the specific operation method comprises the steps of adjusting the pH value of the lithium sulfate solution to 11-12 by using the lithium hydroxide mother liquor, generating calcium sulfate precipitates by using sulfate ions in the lithium hydroxide mother liquor and calcium ions in the lithium sulfate solution, and filtering the calcium sulfate precipitates. According to the technical scheme, the lithium hydroxide mother liquor is used as a remover for removing calcium ions in the lithium sulfate solution, the components of the mother liquor mixed liquor and the proportion thereof are formed, and the actual process verification shows that the lithium hydroxide mother liquor has a good effect on removing the calcium ion content by comparison, and no extra operation procedure is added to the process.)

1. A lithium hydroxide mother liquor for removing calcium ions in intermediate material lithium sulfate is characterized in that: the lithium hydroxide mother liquor comprises, by mass, 8% -10% of lithium hydroxide monohydrate, 1% -2% of sodium hydroxide, 3% -5% of lithium sulfate, 2% -3% of sodium sulfate and the balance of water.

2. The lithium hydroxide mother liquor for removing calcium ions in the intermediate material lithium sulfate according to claim 1, which is characterized in that: the lithium hydroxide mother liquor comprises, by mass, 10% of lithium hydroxide monohydrate, 2% of sodium hydroxide, 5% of lithium sulfate, 3% of sodium sulfate and the balance of water.

3. The lithium hydroxide mother liquor for removing calcium ions in the intermediate material lithium sulfate according to claim 1, which is characterized in that: the lithium hydroxide mother liquor comprises, by mass, 8% of lithium hydroxide monohydrate, 1% of sodium hydroxide, 3% of lithium sulfate, 2% of sodium sulfate and the balance of water.

4. The lithium hydroxide mother liquor for removing calcium ions in the intermediate material lithium sulfate according to claim 1, which is characterized in that: the lithium hydroxide mother liquor comprises, by mass, 9% of lithium hydroxide monohydrate, 1.5% of sodium hydroxide, 4% of lithium sulfate, 2.5% of sodium sulfate and the balance of water.

5. A method for removing calcium ions in lithium sulfate by using the lithium hydroxide mother liquor as claimed in claims 1 to 4, which is characterized in that: and (3) regulating the pH value of the lithium sulfate solution to 11-12 by using the lithium hydroxide mother solution, generating calcium sulfate precipitates by sulfate ions in the lithium hydroxide mother solution and calcium ions in the lithium sulfate solution, and filtering the calcium sulfate precipitates.

6. The method for removing calcium ions in lithium sulfate by using lithium hydroxide mother liquor as claimed in claim 5, wherein the method comprises the following steps: the calcium sulfate precipitate is filtered by filter cloth.

7. The method for removing calcium ions in lithium sulfate by using lithium hydroxide mother liquor as claimed in claim 6, wherein the method comprises the following steps: the filter cloth is 108c type filter cloth.

Technical Field

The invention relates to industrial lithium salt production, in particular to lithium hydroxide mother liquor for removing calcium ions in an intermediate material lithium sulfate solution and a method thereof.

Background

Lithium is an important strategic material and is an indispensable important raw material for modern high-tech products. The total reserve of lithium resources proved by China is the second place in the world, but the lithium yield only accounts for about 5 percent of the total global yield, and the lithium-rich lithium battery is an importation country of lithium products.

Meanwhile, when lithium-related products, namely lithium ion batteries, are applied to new energy automobiles, high-nickel and high-energy density cathode materials become development trends, and currently, the high-nickel cathode materials generally adopt lithium hydroxide as a raw material, so that the lithium hydroxide has a longer market prospect compared with lithium carbonate due to the advantages of lithium hydroxide in crystal structures, solubility and the like.

The existing lithium hydroxide is mainly prepared by adopting a sulfuric acid method, and the lithium hydroxide product is finally obtained by the procedures of roasting, soaking, lithium precipitation, acidification, purification and the like, adding sodium hydroxide into the refined lithium sulfate to decompose lithium hydroxide, freezing to separate sodium to remove sodium sulfate, and carrying out primary evaporative crystallization, redissolution purification, secondary evaporative crystallization and the like on the sodium-separated mother liquor. In the process, the intermediate product lithium sulfate solution contains a large amount of calcium ions, so that the calcium ions of the final product exceed the standard, and the quality of the lithium hydroxide product is influenced finally.

Based on the above, a lithium hydroxide mother liquor for removing calcium ions in the intermediate material lithium sulfate solution and a method thereof are researched and developed.

Disclosure of Invention

The invention aims to: the lithium hydroxide mother liquor for removing calcium ions in the intermediate material lithium sulfate solution and the removing method solve the problems, the concentration of the calcium ions in the intermediate material lithium sulfate solution is reduced to 0-30ppm by setting the components and the proportion of the lithium hydroxide mother liquor, and byproducts are prevented from being generated in the preparation process of lithium hydroxide, so that the technical problems of high impurity calcium content in a lithium hydroxide product in the existing preparation process are solved.

In order to achieve the purpose, the invention adopts the technical scheme that: the lithium hydroxide mother liquor for removing calcium ions in intermediate material lithium sulfate comprises, by mass, 8% -10% of lithium hydroxide monohydrate, 1% -2% of sodium hydroxide, 3% -5% of lithium sulfate, 2% -3% of sodium sulfate and the balance of water.

The technical scheme mainly aims at the intermediate material lithium sulfate solution in the production process of lithium hydroxide, the lithium sulfate solution contains a large amount of calcium ions, and if the calcium ions are not removed, the calcium ion content of the final lithium hydroxide product exceeds the standard, the purity is reduced, and the performance advantage of the final lithium hydroxide product is reduced.

Therefore, the technical scheme provides a lithium hydroxide mother liquor, wherein the lithium hydroxide mother liquor comprises lithium hydroxide monohydrate, sodium hydroxide, lithium sulfate and sodium sulfate, hydroxide ions and sulfate ions in the mother liquor fully react with calcium ions in a lithium sulfate solution under an alkaline condition to generate calcium sulfate precipitate, and then the calcium sulfate precipitate is removed.

The lithium hydroxide mother liquor in the technical scheme is a solution obtained after evaporation of the prepared lithium hydroxide, so that the mother liquor of the lithium hydroxide solution in the production process can be used for effectively treating materials in the production process, and the method is simple in operation steps and strong in operability.

In the technical scheme, the feasibility and the removal cost of subsequent process operation are fully considered in solution components in the lithium hydroxide mother liquor, if sodium ions are introduced, the sodium ions can be removed in the process of producing the lithium hydroxide, and if sodium sulfate is removed by freezing sodium precipitation, the additional removal cost cannot be added to the process by the introduction of the sodium ions, and meanwhile, the introduced lithium ions are inherent to the solution and cannot bring corresponding removal workload to the subsequent production operation; sulfate ions in the lithium hydroxide mother liquor can react with calcium ions in the lithium sulfate solution to generate calcium sulfate, and the calcium sulfate is filtered and removed, so that the aim of reducing the calcium ions in the lithium sulfate solution is fulfilled, and meanwhile, the introduction of hydroxide ions creates a good alkaline environment for the reaction of the calcium ions and the sulfate ions in the lithium sulfate solution, and is beneficial to the generation of calcium sulfate precipitate.

In the technical scheme, the sodium sulfate solution is adopted as the component of the mother solution mixed solution in the lithium hydroxide mother solution, the sodium sulfate solution is adopted instead of the sodium carbonate solution, the sodium carbonate solution can react with the lithium hydroxide to generate lithium carbonate precipitate, and the lithium carbonate precipitate is a byproduct in the lithium hydroxide preparation process, namely other products are introduced in the whole preparation process, so that the production operation cost is increased, and the sodium sulfate solution is preferably used as the component of the lithium hydroxide mother solution.

The selection of the components and the proportion of the mixed solution of the lithium hydroxide mother liquor in the technical scheme is not routine selection of a person skilled in the art, nor can be simply obtained by the person skilled in the art through routine techniques or limited experiments, and the selection of the components of the mixed solution fully considers the removal of calcium ions in the lithium sulfate solution, and also considers the operation and treatment cost in the preparation process of the lithium hydroxide not to be increased, and can reduce the calcium ions in the lithium sulfate solution to the lowest level, namely less than 0.15 g/l.

Further, the lithium hydroxide mother liquor comprises, by mass, 10% of lithium hydroxide monohydrate, 2% of sodium hydroxide, 5% of lithium sulfate, 3% of sodium sulfate and the balance of water.

Further, the lithium hydroxide mother liquor comprises, by mass, 8% of lithium hydroxide monohydrate, 1% of sodium hydroxide, 3% of lithium sulfate, 2% of sodium sulfate and the balance of water.

Further, the lithium hydroxide mother liquor comprises, by mass, 9% of lithium hydroxide monohydrate, 1.5% of sodium hydroxide, 4% of lithium sulfate, 2.5% of sodium sulfate and the balance of water.

The invention also provides a method for removing calcium ions in lithium sulfate by using the lithium hydroxide mother liquor, which is characterized by comprising the following steps: and (3) regulating the pH value of the lithium sulfate solution to 11-12 by using the lithium hydroxide mother solution, generating calcium sulfate precipitates by sulfate ions in the lithium hydroxide mother solution and calcium ions in the lithium sulfate solution, and filtering the calcium sulfate precipitates.

In the technical scheme, the lithium hydroxide mother liquor is used as an additive for removing calcium ions in the lithium sulfate solution, and the lithium hydroxide mother liquor is obtained by evaporating the lithium hydroxide solution prepared from the lithium hydroxide, so that the selection of the removal solvent does not increase the cost of corresponding operation from the material source, and meanwhile, the effect of well reducing the content of the calcium ions can be realized after the addition; the pH value of the lithium sulfate solution is adjusted to 11-12 by using the lithium hydroxide mother liquor, so that a good alkaline environment is provided for the generation of calcium sulfate precipitate, and the content of calcium ions in the solution can be reduced to the maximum.

Compared with the conventional technology in which the pH value is adjusted by adding calcium oxide, the method has the advantages that the introduction of new calcium ions into the intermediate product lithium sulfate solution is avoided, and thus, related preparation procedures are reduced.

In the technical scheme, the generated calcium sulfate precipitate is removed in a filtering mode, and the same removing mode can be adopted for multiple times, so that the content of calcium ions in the lithium sulfate solution is further reduced.

Further, the calcium sulfate precipitate is filtered by adopting a filter cloth, wherein the calcium sulfate precipitate is preferably removed by adopting a filter cloth filtering mode, and the type of the filter cloth is 108C type.

Compared with the prior art, the invention has the advantages that:

1) according to the technical scheme, the lithium hydroxide mother liquor is used as a remover for removing calcium ions in the lithium sulfate solution, the components of the mother liquor mixed liquor and the proportion thereof are formed, and the actual process verification shows that the lithium hydroxide mother liquor has a good effect on removing the calcium ion content by comparison, and no extra operation procedure is added to the process.

2) According to the method for removing the calcium ions in the lithium sulfate solution, the lithium hydroxide mother solution is adopted for producing the calcium sulfate precipitate, and the main components in the mixed solution of the lithium hydroxide mother solution are hydroxide ions and sulfate ions, so that a good alkaline environment is provided for the generation of the calcium sulfate precipitate, and the maximum amount of the calcium ions in the lithium sulfate solution can be removed conveniently.

Detailed Description

The present invention will be further explained below.