西藏班戈湖淡化湖水的自然蒸发和析盐规律

Natural evaporation and crystallization of Bangor salt lake water in Tibet

全球气候变暖给青藏高原的湖泊带来极大的影响,湖泊面积的扩大使湖水淡化严重,针对淡化碳酸盐型盐湖的研究意义重大。现场自然蒸发实验以班戈湖淡化碳酸盐型盐湖为研究对象,以Na+、K+/Cl-、SO2-4、CO2-3-H2O五元体系298 K介稳相图为指导,探讨了湖水的p H值变化以及碱金属元素含量对矿物析出的影响。实验结果显示,淡化湖水在自然蒸发过程中需要经历更长的时间才能出现矿物沉淀。湖水的p H值在经历一个缓慢的降低过程后,在蒸发后期又迅速升高,这主要与湖水中的CO2-3、HCO-3和OH-含量有关,且与之正相关。在影响淡化湖水酸碱性质的主要碱金属元素中,Na的作用大于K,最后是Li。与之对应的矿物也由中性向碱性转变,表现出的矿物析出顺序为芒硝、石盐、钾芒硝、碳酸钠矾和天然碱。利用不同矿物的析出特性可以分阶段进行回收提取,对盐湖资源开发具有现实意义。

Considering the huge impact of global warming on lakes on Qinghai-Tibet Plateau and the serious lake desalination resulting from expanded lake area, the research on carbonate-type desalinated saline lakes is of great significance. Taking the carb0nate-type salt lake of Bangor Lake as the research object, the on-spot natural evaporation experiment has explored the pH changes in lake water and the effect of alkali metal elements content on mineral separation under the guidance of 298 K metastable phase diagram of quinary system of Na＋, K＋/Cl- , SO2-4, and CO32--H2O, Experimental results show that mineral deposits from desalinated lake water would be developed in a longer period in the context of natural evaporation. After a slow reduction process, the pH value of lake water is increased rapidly in the late stage of evaporation, which is mainly related to and positively correlated with the contents of CO^-, HCO3 and OH- in the lake water. Among the main alkali metal elements that affect the acid-base property of desalinated lake water, the role of Na exceeds that of K, followed by Li. Their corresponding minerals are also changed from neutral to alkali property; and the order of separated minerals is mirabilite, halite, aphthitalite, burkeite and trona. Based on the separation characteristics of different minerals, they can be recovered and extracted by stages, which is practically significant in the development of the salt lake resources.