吉兰泰盐湖卤水冻硝及冻硝母液蒸发析盐规律研究

随着盐湖资源长期开采,吉兰泰盐湖卤水逐渐老化,导致再生盐品质逐年下降。为解决卤水老化、SO₄ ^2-富集等问题,对吉兰泰盐湖所处的Na ⁺、Mg ²⁺∥Cl ^-、SO₄ ^2--H₂O体系,采用恒温冷冻法与强制蒸发恒温平衡法,对船采区卤水冷冻析硝和冻硝后卤水蒸发析盐规律进行研究。考察了冻硝温度、加水率、冻硝时间等因素对析硝率和SO₄ ^2-去除率的影响以及蒸发水率对蒸发析盐规律的影响。结果表明：船采区卤水加水率为8%（质量分数）时,卤水密度降至1.197 8 g/cm ³,在-10 ℃冷冻12 h,冻硝后的卤水密度为1.186 6 g/cm ³,卤水中SO₄ ^2-质量浓度降至8.84 g/L,芒硝析出率为73.76%;冻硝后卤水在25 ℃蒸发,卤水密度达到1.260 1 g/cm ³,氯化钠析出率为93.14%,析出固相中氯化钠纯度为96.23%。该研究为船采区卤水生产高品位再生盐的工艺优化提供了理论依据。

Study on salt crystallization law of brine frozen mirabilite and frozen mirabilite mother liquor evaporation in Jilantai Salt Lake

The brine of Jilantai Salt Lake is aging gradually with the exploitation of salt lake resources for a long time,which leads to the decline of recycled salt quality year by year. In order to solve the problems such as brine aging and SO₄ ^2- enrichment,aiming at the Na ⁺,Mg ²⁺∥Cl ^-,SO₄ ^2--H₂O system in Jilantai Salt Lake,the salt crystallization law of frozen mirabilite of dredging area brine and frozen mirabilite mother liquor evaporation was studied by constant temperature freezing method and forced evaporation constant temperature equilibrium method.The effect of freezing mirabilite temperature,water addition rate and frozen mirabilite time on denitrification rate and SO₄ ^2- removal rate were investigated.And the evaporation rate on the salt crystallization of evaporation was also studied.The optimum condition of freezing mirabilite was as follows：the brine addition rate was 8%（mass fraction）,the brine density decreased to 1.197 8 g/cm ³,freeze for 12 h under -10 ℃,then the brine density was low to 1.186 6 g/cm ³,the mass concentration of SO₄ ^2- in brine decreased to 8.84 g/L and the precipitation rate of mirabilite was 73.76%. After the frozen mirabilite,the brine was evaporated until density of the brine reaching 1.260 1 g/cm ³ under 25 ℃.The precipitation rate and purity of sodium chloride were 93.14% and 96.23%,respectively.This study provides a theoretical basis for the optimization of brine production of high grade recycled salt in ship mining area.