Energy-Saving Optimization of Lepidolite Roasting Process and Salt Precipitation Control of Lithium-Extracted Solution
The process and reaction principle of lithium extraction from lepidolite were analyzed.Thermo-dynamic calculation,energy consumption comparison and phase diagram analysis were carried out for the two key steps of lithium extraction process from lepidolite,namely roasting energy saving and hydrometal-lurgical salt precipitation.The results show that the energy consumption of ordinary tunnel kilns is slightly lower than that of ordinary rotary kilns.Considering both investment and heat exchange efficiency,hot air combustion-assisted rotary kiln process with grate cooler is the best sulfate roasting process for lithium ex-traction from lepidolite.Pure mirabilite can be obtained by crystallization of purified leaching solution at 0℃.Na2SO4·3K2SO4 double salt can be obtained by evaporation crystallization at 15～50℃,and the pre-cipitated Na2SO4·3K2SO4 at 25℃is the most.Only lithium-containing mixed salt can be obtained by e-vaporation crystallization at 100℃.
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