川东达州地区地下卤水75℃等温蒸发析盐规律研究

Study on salting-out law of the underground brine in Dazhou area,East Sichuan through isothermal evaporation at 75℃

四川东部达州地区地下卤水资源丰富,卤水储量约为8.23×10^(8) m^(3),富含钠、钾、锂、硼、铷、溴等元素。实验研究了该卤水在75℃等温蒸发过程中溶液pH变化规律、各种元素在溶液和固相中的富集规律,并通过X射线衍射(XRD)检测析出矿物的种类,确定了矿物的析出顺序。实验研究结果表明:溶液pH随着蒸失率的增加而降低;氯化钠在整个蒸发过程中大量析出,氯化钾在蒸失率达到77.3%时开始大量析出,蒸发接近末尾时钙、硼都有部分析出;蒸发过程中矿物的析出顺序为氯化钠→氯化钠+氯化钾→氯化钠+氯化钾+硼酸,蒸发过程中的析盐规律与K+,Na+,Mg^(2+)∥Cl^(-)-H_(2)O(75℃)四元相图吻合。根据蒸发实验数据初步设计出卤水资源利用工艺路线。该研究结果为川东地下卤水的开发和综合利用提供了可靠的基础数据。

Abundant underground brine resources are in the Dazhou area of eastern Sichuan,with reserves of about 8.23×10^(8) m^(3),which are rich in sodium,potassium,lithium,boron,rubidium,bromine and other elements.The change of pH,the enrichment regularity and salting out law during the process of isothermal evaporation at 75℃of the brine was investigated in the experiment.The types of precipitated salts were detected by XRD,and the precipitation order of salts was determined.Experimental research results showed that the solution pH decreased with increasing loss rate.Sodium chloride largely precipitated in the whole evaporation process.Potassium began to largely precipitate as potassium chloride when the evaporation rate reached 77.3%.When the evaporation was near the end,both calcium and boron were partially analyzed.The order of appearance of the salt was:sodium chloride→sodium chloride^(+)potassium chloride→sodium chloride^(+)potassium chloride^(+)boric acid.The law of evaporation was the same as the phase diagram of K^(+),Na^(+),Mg^(2+)∥Cl^(-)-H_(2)O(75℃).Preliminary design of the process route for the utilization of brine resources was based on the evaporation experiment data.The research results provided reliable basic data for the development and comprehensive utilization of underground brine in eastern Sichuan.