Abstract:

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.

Key words: anticline structural area, deep brine, natural evaporation, phase diagram of Na⁺,K⁺,Mg²⁺//Cl^-—H₂O