柴达木盆地南翼山背斜构造区卤水自然蒸发实验

柴达木盆地南翼山背斜构造区卤水属高钙、低镁的氯化钙型卤水,微量元素硼、锂、锶、碘等含量相对较高,具有较高的综合利用价值。选取南翼山背斜构造区约3 000 m处深层卤水在自然状态下蒸发结晶,分析各种离子在固、液相中的分布规律、盐类结晶规律、结晶形态及微量离子的富集规律。结果表明:在室外自然状态下蒸发时,析出的盐中发现了不常见的异性结构的石盐、钾石盐和疑似K（NH₄）Mg₂Cl₆·12H₂O的类光卤石;石盐阶段和钾石盐阶段析盐规律符合Na⁺,K⁺,Mg²⁺//Cl^-—H₂O 相图,钾石盐、光卤石、南极石阶段符合K⁺,Na⁺,Ca²⁺,Mg²⁺//Cl^- —H₂O体系25 ℃简干图;微量离子中,Li ⁺、Br^-、I^-一直富集,其他离子在蒸发后期有不同程度的析出,三氧化二硼可以富集至18.77 g/L,Li⁺最高可以富集至6.520 g/L。蒸发所得的钾混盐是提钾优质原料,实验结果可以为后期综合利用提供参考。

Experiment on natural evaporation of brine in Nanyishan anticline structural area of Qaidam Basin

The brine in Nanyishan anticline structural area of Qaidam Basin is calcium chloride type brine with high calcium and low magnesium.The content of lithium,strontium and iodine is relatively high,which has high comprehensive utilization value.The deep brine about 3 000 m away from Nanyishan anticline structure area was selected and evaporated and crystallized in natural state.And the distribution of various ions in solid and liquid phases,as well as salt crystallization,crystal morphology and enrichment of traceions were analyzed.The results showed that: when the salt was evaporated in the outdoor natural state,the unusual halite,sylvite and carnallite like K（NH₄）Mg₂Cl₆·12H₂O were found in the precipitated salt.The salt evolution law of the halite stage and sylvite stage was basically consistent with the phase diagram of K⁺,Na⁺,Mg²⁺//Cl^- —H₂O,and that of the sylvite,carnallite and antarctic stage was consistent with K ⁺,Na⁺,Ca²⁺,Mg²⁺//Cl^- —H₂O system 25 ℃ simplified diagram;Among the trace ions,Li ⁺、Br^-、I^- had been enriched and other ions precipitated in different degrees in the later stage of evaporation,B₂O₃ could be enriched to 18.77 g/L,and Li⁺ could be enriched to 6.520 g/L.The potassium mixed salt obtained by evaporation was a good raw material for extracting potassium.The test results could provide a reference for later comprehensive utilization.