Lithium hydroxide purification and separation method and lithium hydroxide purification and separation system

Abstract

The invention belongs to the technical field of lithium sulfate based lithium hydroxide production and particularly relates to a lithium hydroxide purification and separation method and a lithium hydroxide purification and separation system. The method includes steps: 1) filtering mixed solution of sodium sulfate and lithium hydroxide through a nanofiltration device to realize sodium sulfate purification and separation and obtain lithium hydroxide solution; 2) concentrating the obtained lithium hydroxide solution to obtain concentrated lithium hydroxide solution. The system comprises a reactor, the nanofiltration device and a disc-tube reverse osmosis device or an evaporation and concentration device in sequential series connection. The nanofiltration device comprises a primary nanofiltration unit or multiple levels of nanofiltration units in sequential series connection, and each nanofiltration unit is provided with a disc nanofiltration membrane. On the whole, according to the lithium hydroxide purification and separation method, sodium sulfate and lithium hydroxide can be separated directly, and easiness in control and low energy consumption in process are realized; in addition, the lithium hydroxide solution passing through the membranes is high in purity, addition of chemical agents is avoided, and low treatment difficulty, few procedures and short process in impurity removal treatment are realized.

Description

technical field [0001] The invention belongs to the technical field of producing lithium hydroxide from lithium sulfate, in particular to a method and system for purifying and separating lithium hydroxide. Background technique [0002] Lithium is an important strategic resource material and an indispensable raw material for modern high-tech products. my country's proven total reserves of lithium resources rank second in the world, but lithium production only accounts for about 5% of the global total, and it is a net importer of lithium products. [0003] Lithium carbonate is the basic material for the production of secondary lithium salts and lithium metal products, so it has become the most used lithium product in the lithium industry, and other lithium products are basically downstream products of lithium carbonate. The production process of lithium carbonate can be divided into salt lake brine extraction and ore extraction according to the source of raw materials. At pr...

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Problems solved by technology

This process has the advantages of large energy consumption, high processing cost and difficulty, high cost, time-consuming, low efficiency and serious pollution.

[0015] After removing impurities, plate and frame filtration is mostly used. Due to the large pore size of the filter cloth, its precision is reduced, resulting in a high solid content in the feed liquid, and the subsequent process does not use effective means to intercept solid impurities, resulting in low product quality. ; The evaporation and concentration process requires more equipment, and the maintenance cost and difficulty are higher

Evaporation and concentration waste water resources and pollute the environment, which is not conducive to the sustainable and healthy development of enterprises

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