Study on Slag Phase Control of Thermal Reduction of Spodumene

Aiming at the problems of low utilization rate of spodumene resources and serious environmental pollution, our team proposes a clean process to produce manganese-silicon alloy for lithium enrichment by carbothermal reduction of spodumene. In this process, the melting point and viscosity of the slag phase are very high, which affects the slag discharge and slag–metal separation. Therefore, this experiment considers the addition of CaO as a slagging agent based on the previous process and tests and analyzes the slag phase under different CaO contents. When the CaO content is 30%, the slag phase is mainly Ca2Al2SiO7; the reduction rate of lithium is 99.02%; the direct yield of the alloy is 89.12%; and the melting point of the slag is 1260 °C. It can melt and wrap the alloy before removing the alloy, which has heat preservation and oxidation resistance. The viscosity of the slag at 1360 °C is 0.11 Pa·s, which is within the optimum viscosity range of the slag in actual industrial production. Experiments show that the addition of CaO is beneficial to the removal of lithium and the separation of slag and metal, which lays a good foundation for the industrialization development of the previous process and improves the economic benefits of the whole process.