Extraction of Lithium from Medium to Low-Grade Lepidolite by Composite Sulfate Roasting-Water Leaching Method AITranslate

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Chinese Library Classification Number:TF826.3[冶金工程]

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Lithium in medium to low-grade lepidolite(0.93%Li)was extracted by roasting-water leaching method with sodium sulfate-calcium sulfate composite sulfate as roasting agent.The effects of roasting process parameters on the leaching rate of lithium were discussed.The thermodynamics and kinetics of the roasting process,the microscopic morphology and phase change of the roasted clinker were studied.The results show that the optimum roasting conditions are as follows:the mass ratio of lepidolite,Na₂SO₄and CaSO₄is 1∶0.197∶0.703,roasting temperature is 950℃and roasting time is 2 h.Under these conditions,the leaching rate of lithium can reach 94.8%by leaching with pure water.Under the optimum roasting conditions,the stable structure of lepidolite is destroyed,and its reactions with calcium sulfate and sodium sulfate mainly produce anorthite,albite and soluble lithium salt.Using unreacted shrinking core model to describe the kinetics of lepidolite roasting in the presence of sodium sulfate and calcium sulfate,the apparent activation energy of the roasting process is calculated to be 52.1 kJ/mol at 825~900℃,indicating that the roasting process is controlled by chemical reaction.