Hydrochemistry and behavior of K, Li and B in summer evaporation of Yiliping salt lake brine in Qaidam Basin

摘要

? 2019 by Journal of Lake Sciences. ? 2019 by Journal of Lake Sciences. Combining with the metastable phase diagram of reciprocal quinary system Na + , K + , Mg 2+ //Cl - , SO 4 2- -H 2 O, the projection phase diagram of water and sodium, this paper studied hydrochemical characteristics of the sulfate-type brine from Yiliping salt lake in Qaidam Basin. They were changed seasonally due to freshwater mixation, selective leaching, and annual temperature difference as the most important factor. While the brine temperature lowered to 0°C, mirabilite crystallized from the brine, the metamorphic coefficient MgSO 4 /MgCl 2 declined sharply, and the hydrochemical characteristic transitioned from magnesium sulfate-type to chloride-type. In this paper, the evaporation experiment of Yiliping brine L10 and L20 had been operated at 20-25°C, and experimental results had been compared with theoretical calculations in the following ways including the evaporation route, chemical compositions of liquid and solid phase, XRD patter analysis, hydrochemical characteristic coefficients, ion behaviors, salt-forming characteristics, and so on. As a result, they were in good agreement with the relative error 5%. Theoretical calculations of the metastable phase diagram Na + ,K + , Mg 2+ //Cl - ,SO 4 2- -H 2 O could be used to guide the actual sulfatetype-brine evaporation better. Then, this paper studied the potash-forming characteristic from the magnesium sulfate-type salt lake brine at 25°C combining with hydrochemical characteristic coefficients KCl/MgCl 2 and MgSO 4 /MgCl 2 . While the metamorphic coefficient MgSO 4 /MgCl 2 is above 0.13, epsomite has crystallized together with potash. Finally, the behavior of Li and B during further evaporation of brine had been theoretical calculated by using several phase diagrams including Li + , borate, and Mg 2+ ions. While the mass ratio of Mg 2+ /Li + in the brine was above 27, it was considered that Li and B had accumulated fully in the concentrated brine in the deposition stage of bischofite and epsomite, and the brine accumulated rate declined to 2.50%-3.20%. So it's necessary to extract Li and B from the brine by utilizing new technologies. This results provide theoretical support for the exploitation and comprehensive utilization of the very high Mg 2+ /Li + and Mg 2+ /B 2 O 3 mass ratio sulfatetype-brine. Combining with the metastable phase diagram of reciprocal quinary system Na + + , K + + , Mg 2+ 2+ //Cl - - , SO 4 4 2- 2- -H 2 2 O, the projection phase diagram of water and sodium, this paper studied hydrochemical characteristics of the sulfate-type brine from Yiliping salt lake in Qaidam Basin. They were changed seasonally due to freshwater mixation, selective leaching, and annual temperature difference as the most important factor. While the brine temperature lowered to 0°C, mirabilite crystallized from the brine, the metamorphic coefficient MgSO 4 4 /MgCl 2 2 declined sharply, and the hydrochemical characteristic transitioned from magnesium sulfate-type to chloride-type. In this paper, the evaporation experiment of Yiliping brine L10 and L20 had been operated at 20-25°C, and experimental results had been compared with theoretical calculations in the following ways including the evaporation route, chemical compositions of liquid and solid phase, XRD patter analysis, hydrochemical characteristic coefficients, ion behaviors, salt-forming characteristics, and so on. As a result, they were in good agreement with the relative error + + ,K + + , Mg 2+ 2+ //Cl - - ,SO 4 4 2- 2- -H 2 2 O could be used to guide the actual sulfatetype-brine evaporation better. Then, this paper studied the potash-forming characteristic from the magnesium sulfate-type salt lake brine at 25°C combining with hydrochemical characteristic coefficients KCl/MgCl 2 2 and MgSO 4 4 /MgCl 2 2 . While the metamorphic coefficient MgSO 4 4 /MgCl 2 2 is above 0.13, epsomite has crystallized together with potash. Finally, the behavior of Li