Evaporation Studies For The Salt Lake Brine In The Dongtaijinaier Salt Lake,Qaidam Basin

Salt lakes are widely distributed in China. It is well known that the evaporation path of brines is essential for the comprehensive utilization of salt lake resources. Therefore, the fundamental evaporating studies are necessary to reveal the process of deposit in salt lakes. It provides an evidence for the rule of salt precipitation in the brine evaporation and comprehensive utilization for brine resources.In the thesis, the surface brine in the Dongtaijinaier Salt Lake and the mother liquor after potassium separating were studied by the natural evaporation in situ and isothermal evaporation at50℃in lab, respectively. The component contents both in solid and liquid phases and the physicochemical properties including density, pH in the liquid phases were determined systematically. During the evaporating processes, the crystallized order of salts for both sample of brines were demonstrated. According to the experimental data, the relation between the component contents and the percent of evaporating lose in the liquid phase diagrams and the crystallization paths as well as the physicochemical properties versus evaporating lose rate diagrams were plotted.(1) The natural evaporation process of the surface brine in the Dongtaijinaier, the evaporation experiment results showed there are nine types of salts corresponding to halite, epsom, picromerite sylvinite hexahydrite, carnallite, kainite bischofite and lithium salt while borate was not crystallized out but concentrate further in the relatively mother liquor. The relative amounts of salts crystallized from the same volumes of600L brines were that:94.59kg of halite,168.11kg of epsom salt19.10kg of picromerite,1.76kg of sylvinite,4.04kg of hexahydrite,3.46kg of carnallite,2.46kg of kainite,0.16kg of lithium salt,1.95kg of bischofite. The crystallized paths agree well with the quinary metastable equilibrium system of Na+, K+, Mg2+//Cl-, SO42-H2O at15℃. For the mother liquor of potassium separated sample, the mounts of crystallized hexahydrite, and carnallite salt through freezing in the potassium separated from of the55.1kg mother liquid were that:260g of halite,4740g of hexahydrite,1580g of carnallite,7.7g of halite,680g of bischofite and107g of lithium sulfate monohydrate when the brine of2.5kg was evaporated at50℃.(2) The evaporation experiments with the surface brines from Dongtaijiner Lake, The ion concentrations were varied regularly according to the changes of the percent of evaporating lose. More amounts of halite and sylvinite were crystallized out, so we can use this solution to produce pure bischofite. And then lithium salt and boron salt were not crystallized out but concentrate in the mother liquor. The mounts of crystallized hexahydrite, and carnallite salt through freezing in the potassium separated mother liquor brines, the results demonstrated it was possible to make a high concentrated lithium-containing brine through the solar pond technique. The component contents and physicochemical properties including density, pH in the liquid phase were also determined. With the rate of evaporating lose increasing for the two samples, density of liquid phase increases whereas pH value decreases. This results could be used as a good references for exploiting salt resources.