The 288.2 K Isothermal Evaporation Experiment of Potassium Precipitation Brine in West Taijinair Salt Lake

Abstract

Rubidium and cesium are important strategic resources, and West Taijinar Salt Lake is rich in rubidium and cesium reserves, while the concentration is low and the relationship with coexisting potassium and magnesium ions is complex. In order to understand the evaporative enrichment and salt precipitation patterns of rare elements such as lithium, rubidium, cesium, and boron of the brine after potassium precipitation in West Taijinar Salt Lake, the 288.2 K isothermal evaporation experiment was carried out. The experimental results show that during the evaporation process at 288.2 K, the following salts precipitate from the brine after potassium crystallization: halite (NaCl), bischofite (MgCl2·6H2O), carnallite (KCl·MgCl2·6H2O), hexahydrite (MgSO4·6H2O), epsomite (MgSO4·7H2O), boric acid (H3BO3), and lithium sulfate monohydrate (Li2SO4·H2O). The concentrations of lithium and boron are significantly enriched, the content of Li+ was enriched from 1.7 g/L to 5.63 g/L, and the B2O3 content was enriched from 6.72 g/L to 50.78 g/L. The isomorphism phenomenon of Rb+, Cs+, and K+ makes Rb+ and Cs+ enter potassium ore to form solid solution-type carnallite ((K, Rb)MgCl3·6H2O, (K, Cs)MgCl3·6H2O)) and reduce the content of brine. This study provides data support for the development and comprehensive utilization of lithium, boron, rubidium, and cesium resources in West Taijinar Salt Lake.