西藏扎布耶盐湖卤水273K等温蒸发实验

273K isothermal evaporation of the Zabuye salt lake brine, Tibet,China

西藏扎布耶盐湖卤水中蕴藏着丰富的矿产资源,具有巨大的开发利用价值。盐田相分离技术是盐湖卤水资源开发利用的有效手段,而盐湖卤水蒸发实验是盐田相分离技术的基础。通过对西藏扎布耶盐湖冬季卤水进行273 K等温蒸发实验,研究了蒸发过程中盐类结晶析出规律,发现扎布耶冬季卤水273 K等温蒸发析盐顺序为石盐、芒硝、硼砂、泡碱、钾石盐、碳酸锂,与Na+、K+//Cl-、CO2-3、SO2-4—H2O五元水盐体系298 K相图有一定区别;锂在实验中得到了有效的富集,与原卤水相比浓缩倍数达3.66倍;钾主要以钾石盐的形式于蒸发实验中后期结晶析出,可得到较高品位的钾混盐,其中钾石盐品位最高可达到17.13%,很适合后续提取;硼砂在整个蒸发过程均有析出,相比高温条件,硼砂析出较分散且含量不高,不利于其利用。扎布耶年均气温在0℃左右,该等温蒸发实验可为低温条件下开发利用扎布耶盐湖卤水资源提供基础依据。

Zabuye salt lake is located in the interior of the Tibetan Plateau, China. With its brine rich in mineral resources, the lake is of great economic value. Those resources can be effectively exploited using solar pond technology. As a foundation for solar pond technology, evaporation experiments on salt lake brine were conducted in this study. An isothermal evaporation experiment was carried out at 273 K on the winter brine from Zabuye salt lake. According to the experiment, the crystallization path of salts has been obtained, and the precipitation sequence during 273 K isothermal evaporation was halite （NaC1）, mirabilite （Na2SO4·10H20）, borax （Na2B407· 10H20）, natron （Na2CO3· 10H20）, sylvite （KC1）, and zabuyelite （Li：CO3）, which is different from that of the metastable phase diagram of the quinary system Na＋, K＋//CI-, CO-2/3 SO-2/4-H20 at 298 K. In the experiment, lithium was enriched effectively in the brine, with its concentration up to 3.66 times compared with that of the original brine. Potassium precipitated as sylvite in the late stage of the evaporation process, and the content of potash reached 17.13% in solid phases. Although borax precipitated during the whole evaporation process, high grade borax cannot be obtained in the experiment. The data of the isothermal evaporation experiment at 273 K can be used as the foundation to exploit the Zabuye salt lake brine resources.