Green Extraction Of Lithium From Waste Lithium Aluminosilicate Glass-Ceramics Using A Water Leaching Process

An acid-free leaching process for lithium extraction from waste lithium aluminosilicate (LAS) glass-ceramics was investigated. Lithium was extracted by a water leaching process after calcination with CaO or a CaO-CaCl2 mixture. Compared to extraction using only CaO calcination, the addition of CaCl2 to CaO can significantly reduce the Si:Ca mixing ratio as well as the thermal treatment temperature. A drastic decrease in thermal treatment and leaching time was observed during the experiments. Base don thermodynamics calculations and X-ray diffraction analysis, the crystalline phase that determined the lithium extraction mechanism was investigated. In substituting CaO with CaCl2, the lithium leaching rate initially decreased or remained constant due to a decrease in the LiAlO2 phase. However, the lithium leaching rate gradually increased with increasing CaCl2 substitution rate, caused by an increase in the formation of the LiCl phase. In addition to lithium, calcium and chloride were also observed during the water leaching process. The leaching rate was independent of the thermal treatment and leaching time. Considering conventional lithium purification techniques, a green process for lithium extraction, purification, and recovery from waste LAS glass-ceramics is proposed. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.