西台吉乃尔盐湖析钾老卤及冻卤25℃等温蒸发实验研究

Study on isothermal evaporation of potassium⁃extracted old brine and frozen brine in West Taijinar Salt Lake at 25℃

为了有效利用西台吉乃尔盐湖析钾后老卤及冻卤中的锂、硼等元素,对西台吉乃尔盐湖析钾后老卤和冻卤展开了25℃等温蒸发实验,采用化学分析、X射线粉晶衍射等方法对析出固体矿物的含量及物相进行了分析,并依据Li^(+),Mg^(2+)∥Cl^(-),SO_(4)^(2-)—H_(2)O四元体系25℃介稳相图对盐类析盐路线进行了理论分析。结果表明,析钾老卤蒸发过程主要析出钠石盐、光卤石、水氯镁石、四水泻盐和一水硫酸锂,其中Li^(+)富集到5.4 g/L左右时开始析出锂盐,而硼富集到46.73 g/L时仍无明显析出;冷冻后老卤蒸发过程中可获得较高品质的水氯镁石,冷冻脱硫后可以提高Li^(+)的富集浓度,但最终仍有一水硫酸锂析出。该老卤25℃的蒸发析盐规律与Li^(+),Mg^(2+)∥Cl^(-),SO_(4)^(2-)—H_(2)O四元体系25℃介稳相图基本一致。

In order to effectively utilize the boron and lithium in the old brine and frozen brine of West Taijinar Salt Lake,the isothermal evaporation of potassium‐extracted and frozen potassium‐extracted brine in West Taijinar Salt Lake was conducted.The chemical analysis and x-ray powder crystal diffraction methods were used to analysis the content and phase compositions of solid phase.The theoretical route of crystallization was analyzed using the metastable phase diagram of the quaternary system Li^(+),Mg^(2+)∥Cl^(-),SO_(4)^(2-)—H_(2)O at 25℃.The results indicated that the evaporation process of the potassiumextracted old brine mainly precipitated halite,carnallite,bischofite,starkeyite,lithium sulphate monohydrate.Lithium salt began to precipitate when Li^(+)was enriched to about 5.4 g/L,while there was still no obvious precipitation when boron was enriched to 46.73 g/L.High quality bischofite could be gained at the evaporation stage of old brine with pre‐frozen,and the concentration of lithium ion was increased compared with the former,but the lithium sulphate monohydrate was still precipitated in final.The crystallization route was basically consistent with the metastable phase diagram law of the quaternary system Li^(+),Mg^(2+)∥Cl^(-),SO_(4)^(2-)—H_(2)O at 25℃.