Recycling Lithium from Waste Lithium Bromide to Produce Lithium Hydroxide.

Lithium resources face risks of shortages owing to the rapid development of the lithium industry. This makes the efficient production and recycling of lithium an issue that should be addressed immediately. Lithium bromide is widely used as a water-absorbent material, a humidity regulator, and an absorption refrigerant in the industry. However, there are few studies on the recovery of lithium from lithium bromide after disposal. In this paper, a bipolar membrane electrodialysis (BMED) process is proposed to convert waste lithium bromide into lithium hydroxide, with the generation of valuable hydrobromic acid as a by-product. The effects of the current density, the feed salt concentration, and the initial salt chamber volume on the performance of the BMED process were studied. When the reaction conditions were optimized, it was concluded that an initial salt chamber volume of 200 mL and a salt concentration of 0.3 mol/L provided the maximum benefit. A high current density leads to high energy consumption but with high current efficiency; therefore, the optimum current density was identified as 30 mA/cm. Under the optimized conditions, the total economic cost of the BMED process was calculated as 2.243 USD·kgLiOH. As well as solving the problem of recycling waste lithium bromide, the process also represents a novel production methodology for lithium hydroxide. Given the prices of lithium hydroxide and hydrobromic acid, the process is both environmentally friendly and economical.