西藏扎北盐湖夏季卤水自然蒸发实验研究

摘要

西藏扎北盐湖位于藏北高原腹地,其卤水类型属硫酸钠亚型,富含Li、K、B等元素.为综合利用该湖的液态矿产资源,于西藏当地对该盐湖富锂卤水进行自然蒸发实验.实验以Na+,Mg2+//Cl-,(SO2-4) -H2O四元体系15℃等温相图及K+,Mg2+//(SO2-4)-H2O三元体系15℃介稳相图为参考,绘制了扎北盐湖夏季卤水在秋季自然蒸发结晶路线图,研究了卤水在蒸发过程中液相的化学组成变化以及其蒸发析盐规律.结果表明,在蒸发过程早期(成卤率23.9％),锂浓度达1.2 g/L时,锂开始以Na3 LiSO4·3H2O等复盐形式大量分散析出；硼在整个蒸发过程中以硼砂( Na2B4O7·10H20)等形式分散析出难于富集；钾以钾镁矾(K2SO4·MgSO4·6H2O)和钾石盐(KCl)形式蒸发浓缩的后期大量析出.实验为扎北盐湖的盐田工程设计及制卤工艺操作提供了必要的基础数据,也可为我国西藏硫酸钠亚型盐湖卤水的综合利用提供一定参考.%Zabei Salt Lake is located in the central region of Northern Tibet, China. The sodium sulfate subtype brine of Zabei Salt Lake is rich in Li, K, B and other elements. For comprehensive utilization of mineral resources of the salt lake, natural evaporation of the lithium-rich brine was carry out in the site of DXC Field Observation Station nearby Zabei Salt Lake. Based on the phase diagram of Na* ,Mg2+//Cl-, SO2-4- H2O and K+ 、Mg2+ //SO2-4- H2O 15 °C system, the salts crystallization path of the brine natural evaporation was drawn. And the variation of elements contents in the liquid phase and solid phase through the evaporation was discussed. The results showed that; lithium and boron is precipitated as lithium double salt and borax in the whole evaporation process, and potassium is precipitated as leonite and sylvite until the brine is extremely concentrated. The experiment provide the basic data for future comprehensive utilization of Zabei Salt Lake.