Deep impurity removal method for cell-grade lithium chloride

Abstract

The invention provides a deep impurity removal method for cell-grade lithium chloride. The method comprises the following steps: a lithium-containing solution is subjected to preliminary impurity removal, then pH is regulated to 10-12, the solution passes through a chelating cation exchange resin column, so that bivalent or higher metal cations in the lithium-containing solution are adsorbed, a lithium-containing purified liquid is obtained and is evaporated, crystallized and dried, and cell-grade lithium chloride is obtained; then the chelating cation exchange resin column is replaced with deionized water, pickled with a hydrochloric acid solution and subjected to reacted acid washing with deionized water, alkaline washing with a sodium hydroxide solution and residual alkali washing withthe deionized water sequentially, and the recyclable chelating cation exchange resin column is obtained. According to the deep impurity removal method for cell-grade lithium chloride, deep impurity removal of cell-grade lithium chloride can be completed once, cell grade is reached, precipitates cannot be produced, impurity removal cost and environmental protection risks are reduced, lithium recovery rate is increased, and the chelating cation exchange resin column is recyclable, so that the impurity removal cost is saved.

Description

technical field [0001] The invention relates to the technical field of lithium production, in particular to a deep impurity removal method for battery-grade lithium chloride. Background technique [0002] In the process of using spodumene, lepidolite leached lithium sulfate solution or lithium chloride-containing brine to prepare anhydrous lithium chloride, the current production method is to put calcium chloride solution into the solution or use sodium salt freezing method Obtain the crude lithium chloride liquid, then add impurity remover for many times, filter for many times to remove various impurity ions, and finally evaporate and crystallize to obtain lithium chloride product; or use lithium carbonate and lithium hydroxide to directly react with hydrochloric acid to obtain lithium chloride solution, the lithium chloride product is obtained after evaporation and crystallization. [0003] In the process of producing battery-grade lithium chloride, after obtaining the pr...

AI Technical Summary

Problems solved by technology

[0004] 1. Calcium ions and magnesium ions in the solution react with the impurity remover to form precipitates, which need to be separated by filtration. In order to facilitate the treatment of waste residue, these two kinds of precipitates are generally separated by filtration, which leads to high energy consumption and labor intensity.

Chloride ions and lithium ions will also be entrained in the precipitation, which will not only increase the cost of environmental protection but also increase the loss of lithium during waste residue treatment.

[0005] 2. It takes a long time for calcium ions to react with sodium carbonate to form calcium carbonate precipitation, and the initial precipitation particle size is very fine, which is difficult to filter. It takes about ten hours of reaction time to form precipitation grains, and the time cost is huge

[0006] 3. Calcium ions react with sodium carbonate to form calcium carbonate precipitates. The effect of removing calcium ions often does not meet the requirements for the production of battery-grade products, and multiple removal operations are required.

[0007] 4. The reaction of magnesium ions and sodium hydroxide to produce magnesium hydroxide precipitation needs to be carried out under alkaline conditions with a pH value greater than 11, which increases the risk of scaling on the inner walls of pipes and containers

[0008] At present, scientific research workers have done extensive research on the production methods of lithium chloride, and have researched and developed various deep impurity removal methods such as adding EDTA and organic extractants, but the cost is high, the number of impurity removals is high, and the process is difficult. Large losses are a common problem with these methods

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