Study On Extracting Lithium From Lepidolite And Preparation Of Lithium Chloride

The development of lithium has been enlarged in many high-tech fields. Accelerated the exploitation of lithium resource and improved the technology of lithium salts' working are new tasks in the world inorganic salt industry. This paper mainly declares the method of extracting lithium from lepidolite and preparing the lithium chloride by double-decompose reaction with material lithium sulfate and calcium chloride.Firstly, the method of extracting lithium from lepidolite has been studied. During the study, many factors, such as: density of H2SO4 solution, reaction ratio of materials, reaction temperature and time, are studied how to effect the extraction yield of Li2O. After these studies, the optimal conditions are summarized: 50% H2SO4 solution and lepidolite powder which has been grounded to a particle size of 80~100microns, react at 2:1ratio,120℃ temp for 8h～10h. Marinated it with two times volume of reaction solution for 12h. Detected the ions in solution, such as Li,K,Na,Mg,Al,Si,Fe, et al by ICP-AES. The extraction yield of Li2O can reach over 95%.Neutralizing the excessive acid in solution with Ca(OH)2, adjusting the pH value to 12~13 sequentially. Most heavy metal ions can be removed as hydroxide. Vaporizing the solution till the volume to 1/5 raw liquid. Cooling it, K,Na sulfate mostly can be removed at 0℃ temp. So the content of Li2SO4 solution is about 1.6mol/L.Secondly, the process of preparing LiCl with Li2SO4 and CaCl2 by double-decompose reaction has been studied. During the study, many factors, such as: reaction ratio, temp, time and pH value, temp of drying product, all of these are studied clearly how to effect the purity of LiCl. After these study, the optimal conditions are obtained. The raw materials, Li2SO4 and CaCl2, react at the equal mol, 90℃ temp for 30min. Cooling, filtrating, the mother liquor of LiCl is obtained. Neutralizing the liquor with 6mol/LHCl, adding BaCl2 to remove the excessive SO42-, and remove the excessive Ba2+ and Ca2+ with Li2CO3. Filtrating, liquor till the LiCl solution is nearly saturate, adjusting the pH to neutral. Condensing sequentially, the LiCl solution begins to crystallization, then fries the crystal in porcelain crucible.The product, LiCl, is obtained. The product has been analyzed.The purity of LiCl can reach over 99.0%, according to the standards of LiCl-1.Lastly, compared the operating costs with old processes. The compare declares that this process of preparation of LiCl by double-decompose reaction is not only cheaper obviously but also easier to get raw materials.