蛇纹石酸浸淋洗液中硫酸镁的溶析结晶优化

Study on Optimization of Extracting Magnesium Sulfate from Acidleaching Eluent of Serpentine by Solventing-out Crystallization

为了充分的利用我国含镁非金属矿资源,提高蛇纹石中所含镁资源的综合回收率,本研究提出了一种在常温常压下从蛇纹石矿淋洗液中富集镁元素的新工艺。该工艺采用了溶析结晶法对蛇纹石酸浸淋洗液中的镁进行回收,通过响应曲面法优化实验条件,明确较佳的结晶工艺条件。研究过程中考查了结晶温度、结晶时间以及溶析剂无水乙醇用量对硫酸镁结晶析出的影响及主要因素之间的交互作用,由研究结果可得较佳的优化条件为:结晶时间为97 min,结晶温度为18°C,无水乙醇用量为68 mL,该条件下硫酸镁的析出率可达93.52%,与回归方程模型的预测值相吻合。同时通过响应曲面图和等高线图分析,更加直观反映了各个因素对硫酸镁析出率的影响及交互作用的强弱,结果表明,无水乙醇用量显著影响硫酸镁的析出,结晶温度影响较小,无水乙醇用量与结晶温度及时间的交互作用都比较显著。研究过程中获得的结晶产物为棒条状的六水硫酸镁,符合国内Ⅳ类MgSO4·nH2O产品的生产要求。

In order to make full use of China's non-metallic mineral resources containing magnesium,and improve the comprehensive recovery rate of magnesium in serpentine,a new process of enriching magnesium from serpentine leaching solution at normal temperature and pressure was proposed. In this process, the solution crystallization method was used to recover the magnesium from the acid leaching solution of serpentine. The test conditions were optimized by response surface methodology to determine the optimal crystallization process conditions. In this study, response surface method was employed to optimize test conditions and select the best crystallization process conditions. In addition, the effect and interaction of crystallization time, temperature, and absolute ethanol consumption on magnesium sulfate crystallization efficiency were study. The results showed that the magnesium sulfate crystallization efficiency reached 93.52% under the optimum condition (crystallization time: 97 min, crystallization temperature: 18°C and absolute ethanol consumption: 68 mL). Moreover, the absolute ethanol consumption exhibited significant influence on magnesium sulfate crystallization, while temperature had the least effect, and the interaction between absolute ethanol consumption and crystallization temperature or time was significant. The crystalline product was rod-shaped magnesium sulfate hexahydrate, which met the production requirements of domestic class IV MgSO4·nH2O products.