Method for preparing battery grade lithium hydroxide monohydrate

Abstract

The invention discloses a method for preparing battery grade lithium hydroxide monohydrate, which comprises steps: edulcoration and purification of lithium sulfate solution, freezing separation, preparation of lithium hydroxide monohydrate crude products, dissolution and purification of the lithium hydroxide monohydrate crude products and recrystallization. The method for preparing the battery grade lithium hydroxide monohydrate can obtain lithium hydroxide monohydrate finished products just through twice crystallization, and improves leaching efficiency of lithium. Sodium sulfafe decahydrate which is frozen and separated is washed through low temperature water, the lithium in the sodium sulfafe decahydrate is effectively recycled, the technological process is reduced, the yield of the lithium is further greatly improved, the investment of evaporator equipment is reduced, and the cost effectiveness is obvious.

Description

technical field [0001] The invention belongs to the technical field of battery material production, and in particular relates to a method for preparing battery-grade lithium hydroxide monohydrate. Background technique [0002] As one of the raw materials for lithium-ion battery materials, battery-grade lithium hydroxide is in increasing demand every year. At present, the methods for preparing battery-grade lithium hydroxide mainly include: spodumene concentrate sulfuric acid leaching freezing method and ordinary lithium carbonate lime causticization method. The lithium carbonate lime causticization method has not been applied on a large scale due to high cost, and spodumene The sulfuric acid leaching and freezing process of concentrate is widely used, but the current process of spodumene concentrate sulfuric acid leaching and freezing process requires three times of crystallization and purification to obtain qualified battery-grade monohydric hydroxide after leaching lithium...

AI Technical Summary

Problems solved by technology

At present, the methods for preparing battery-grade lithium hydroxide mainly include: spodumene concentrate sulfuric acid leaching freezing method and ordinary lithium carbonate lime causticization method. The lithium carbonate lime causticization method has not been applied on a large scale due to high cost. Spodumene The process of sulfuric acid leaching and freezing of concentrate is widely used, but the current process of spodumene concentrate sulfuric acid leaching and freezing must go through three times of crystallization and purification after leaching lithium from the ore to obtain lithium sulfate leaching solution to obtain qualified battery-grade monohydric hydroxide For lithium products, after three times of evaporation and crystallization, not only the amount of investment in the evaporator is large, but also the energy consumption is high, and a considerable part of the lithium liquid will be taken away by the evaporated steam during the evaporation and concentration of the lithium hydroxide solution, resulting in a further increase in the yield of lithium. This is the most fundamental reason why the lithium yield of this process has been low all the time. At the same time, another important reason for the low lithium yield is that the surface of the sodium sulfate decahydrate that is frozen and separated from the high-concentration lithium hydroxide solution is also frozen. A considerable part of lithium is taken away, so in order to reduce the production cost of battery-grade lithium hydroxide, in addition to shortening the process flow, the loss of lithium must also be reduced