Research On Colour-Removal From Raw Lithium Carbonate In Zabuye Lake, Tibet

Zabuye Lake is a typical carbonate salt lake in Qinghai-Tibet Plateau. The content of lithium is above 1000mg/l, and the ratio of Mg to Li is low. So Li2CO3 can separate out directly.Zheng Mianping , the famous academician of Research and Development Center of Saline Lake and Epithermal Deposits, Chinese Academy of Geological Sciences, and the high-tech Ltd. of lithium industry in Zabuye Tibet have done research on extracting lithium from salt lakes for many years. Their production process is 'freeze-concentration-crystallization'. The content of Li2CO3 in the mixed salt production is about 20%-60%. Besides Li2CO3, this raw production contains Na+, K+, Cl-, SO42- and some unknown coloring component.To remove the color from the raw Li2CO3, many research efforts have been done. First, the causation of coloring has been studied. Then, three experiments, washing experiment, acid dissolve experiment and bicarbonating experiment, have been designed for decolorization. The best one is bicarbonating treatment. These efforts are introduced in this paper.Through these treatments, the refined Li2CO3 can measure up to the industry standard. Some valuable experimental data are obtained, which will provide the basis for optimization of production practices and parameters.The Pitzer theory is applied to predict the solubility of salt in Li+,Na+(K+)//Cr, CO32--H2O system, and the phase diagram is made. According to the mathematical model, the material consumptions are calculated, which are accurate enough to meet most experimental results. This will be an active contribution to the lithium industry.