氨碱废液溶采二层盐制备优级液体盐工艺研究

针对内蒙古吉兰泰盐湖补水困难、二层盐硫酸根含量高、氨碱废液排量大后处理困难等技术难题,分别探究了二层盐饱和卤水混配氨碱废液制备液体盐工艺,以及氨碱废液混兑蒸馏水后溶采二层盐制备液体盐工艺。通过在线拉曼实验,测得该反应达到平衡需要1 h以上;探究了机械搅拌速率、化学反应时间、氨碱废液与蒸馏水混配比例等因素对液体盐氯化钠、硫酸根、钙离子含量的影响。结果表明：在硫酸根和钙离子物质的量比为1∶1、25 ℃、300 r/min条件下,氯化钙和硫酸钠的反应过程是二水硫酸钙结晶过程的速率控制步骤;二层盐饱和卤水混配氨碱废液制备液体盐工艺中,在相同条件下,反应120 min后分离可获得优级液体盐;氨碱废液混配蒸馏水后直接溶采二层盐制备液体盐工艺中,氨碱废液与蒸馏水体积混配比例为1∶（5.55~6.36）、25 ℃、300 r/min条件下,反应120 min后分离可获得优级液体盐。

Study on the process of preparing liquid salt of guaranteed reagent by dissolving two-layer salt in ammonia-alkali wastewater

In view of the technical problems of Jilantai Salt Lake in Inner Mongolia such as difficulty in replenishing freshwa-ter,high sulfate content in the two-layer salt and difficulty in post-treatment of ammonia-alkali wastewater,the process of preparing liquid salt by mixing two-layer salt saturated brine with ammonia alkali waste liquid and the process of preparing liquid salt by dissolving two-layer salt after mixing ammonia alkali waste liquid with distilled water were studied,respectively.From the online Raman experiment,it was measured that the reaction took more than 1 h to reach equilibrium.The ef-fect of mechanical stirring rate,chemical reaction time,mixing ratio of ammonia alkali waste liquid and distilled water on the contents of NaCl,SO₄^2- and Ca²⁺ in liquid salt were investigated.The results showed that the reaction process of CaCl₂ and Na₂SO₄ was the rate controlling step of CaSO₄·2H₂O reaction crystallization process under the conditions of the molar ratio of SO₄^2- and Ca²⁺ was 1∶1,25 ℃,300 r/min.Under the same conditions,it took more than 120 minutes to produce the liquid salt of guaranteed reagent during the technology route of preparing liquid salt by mixing two-layer salt saturated brine with ammonia alkali waste liquid.In the the process of preparing liquid salt by dissolving two-layer salt after mixing ammonia alkali waste liquid with distilled water,under the conditions of volume ratio of ammonia-alkali waste liquid to freshwater was1∶（5.55~6.36）,25 ℃,300 r/min,the optimal liquid salt was obtained by separation after reaction for 120 min.