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There are rich lithium resources in salt lakes. As a kind of energy metal in 21 Century, lithium has been widly used in all walks of life. Trace lithium and massive alkaline metals often coexist in salt lake brine, especially a large number of magnesium ions which have a similar nature with lithium-ions make the technology of extraction and separation of lithium-ions difficult and hamper the development of salt lake industries, especially the lithium salt industries. At present, the separation of magnesium and lithium in salt lake containing high magnesium- lithium ratio is a key technical problems in the development of salt lake brine.In this study,I take the West taijnar Salt Lake acidified brine (Mg / Li≈20) for the research object, proceed from the point of the comprehensive utilization of resources, lower cost of lithium-extraction ,and reform the method of traditional boron- magnesium coprecipitation.The method is that I add additives to improve the crystallization of calcium sulfate, calcium sulfate form rod-like crystallization, which form bridging role in the process of filter and reduce the inter-particle bonding of magnesium hydroxide, making the cake loose and reducing the filtration resistance, thus speed up the filtering speed significantly and reduce the loss of lithium. Compared to existing method of boron- magnesium coprecipitation,the loss of lithium is only 15%, which is decreased by more than 60%.The results show that: it is better to devided the addition of lime milk into two-step , control the pH of the first paragraph at 8, and the second at 10.5, so that magnesium ions can be completly removed.The loss of lithium is respectively about 10% and 5%, and about 55%～60% of lithium can be recovered through washing, so that the lost of lithium in coprecipitation of boron-magnesium is about 7%. At the same time, more than 75% of the boron entered into solid of the first paragraph, which is favorable to the leaching of boron, and the leaching rate of boron is about 45%.In the process of calcium removal,the loss of lithium is about 5.5%.Through washing, about 80% of the lithium can be recycled, and the lotion can be sued in lime slaking in order to recycling lithium.By adding mixed surfactant LAS/ASC precipitation in the process of vaporation, the entrainment of lithium in precipitated sodium chloride can be reduced, and the loss of lithium is about 6%.
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