Purification of lithium chloride from brine

What is LiCl

Lithium chloride (formula LiCl) is a typical ionic compound with excellent solubility in polar solvents such as water. It is one of the primary sources of Lithium (Li+) metal. LiCl is mainly extracted from lithium brines.

Lithium brine deposits

Liquid lithium brine reservoirs are located beneath salt flats, known as salars, most of which are in South America, Canada, and China. Other lithium-rich brine resources include geothermal, seawater and oil field brines. Brine has a theoretical lithium content of about 3 %.

Use of Lithium chloride

Lithium chloride is mainly used for the production of lithium metal by electrolysis of a LiCl/KCl. LiCl is also used as a brazing flux for aluminium in automobile parts. It is frequently used as desiccants (for drying air streams) or in biochemical applications to precipitate RNA from cellular extracts.

How does it work?

The innovation is based on partial concentration by RO to roughly 40,000 mg/L concentrates followed by electrodialysis using demineralized water as the receiving water and concentrate to a level above 80,000 mg/L dissolved solids. After chelating IX and evaporation, a crystallizer is used to produce the final product, such as lithium chloride etc.

What is the proposed unit operation train

NF → RO + ED → EV → Crystallization

NF – Nanofiltration, RO – reverse osmosis, ED – electrodialysis, EV - evaporation

How could the block flow diagram work

The common NF permeate could be concentrated up to 4 times by RO with no antiscalant.

The RO retentate could be concentrated 2 times by EDR with no antiscalant.

The ED concentrate is purified by the B and Si removal unit.

The final concentration step is evaporation combined with LiCl / NaCl crystallization step. The product is commodity grade LiCl.

Benefits of using MEGA electrodialysis in conventional lithium brine extraction processes

The current invention method aims to increase the Li yield of the entire production by recovering more lithium from the extraction process itself and additionally from the waste mother liquors. The main benefits of electrodialysis are:

• Special configuration ED reduces the complexity of production and waste management.
• ED is reaching high levels of silica and boron retention over 97 %.
• Electrodialysis lowers the amount of water-salt solutions for handling.
• Electrodialysis is saving costs for evaporation and crystallization.
• Electrodialysis is pulling ions resulting in 80,000 mg/L maximal concentration for LiCl .
• Green technology.

Limited lithium reserves and the increasing costs of its recovery are increasing pressure on lithium brine processors, who are facing new challenges in the cost and efficiency of current lithium brine recovery methods. Therefore MEGA has developed this new solution for lithium brine mining.