Lithium recovery from pretreated α‐spodumene residue through acid leaching at ambient temperature

Abstract A novel alkaline hydrothermal approach for low‐temperature conversion of α‐spodumene into Li2SiO3 residue was proposed, providing a promising method for extracting lithium from α‐spodumene as a pretreatment process. This work proposed a systematic investigation for extracting lithium from the residue by acid leaching and preparing lithium carbonate. The reaction feasibility between Li2SiO3 and acids (HCl and H2SO4) was first evaluated through thermodynamic calculation. Compared with the leaching effects of hydrochloric acid and sulphuric acid, sulphuric acid is the preferred leaching agent due to its higher extraction efficiency for lithium and lower acid consumption. Lithium extraction efficiency from the residue achieved up to 87.48% under the following optimized conditions: 0.75 mol/L H2SO4, 0.4 times the theoretical amount of acid, 10 min, 30°C, and 100 rpm. Based on the optimized conditions, the lithium‐containing solution was concentrated through three consecutive cycles of leaching, which obtained a concentration of 17.78 g/L for lithium. The leaching solution was purified by CaO‐Na2CO3, resulting in the removal rates of SiO32−, Mg2+, and Ca2+ of 84.22%, 95.51%, and 90.55%, respectively. Finally, the solution was precipitated with sodium carbonate to prepare Li2CO3. This paper facilitates the development of an economical process for efficient lithium extraction from spodumene at low temperatures.