含钙硫酸镁溶液闪冷结晶过程颗粒粒度控制研究

Study on Particle Size Control in Flash Crystallization Process of Magnesium Sulfate Solution containing Calcium

工业硫酸镁废水通常采用蒸发浓缩与闪冷结晶结晶相结合的处理方法。文章针对含有少量钙离子的硫酸镁废水闪冷结晶结晶过程产品粒度过小的问题,对硫酸镁闪冷结晶结晶过程进行系统研究。通过静态平衡法实验确定了质量分数为0.1%的硫酸钙溶液中硫酸镁的溶解度,并确定不同温度条件下的硫酸镁平衡固相类型。同时采用单因素法考察了溶液浓度,闪冷压力和搅拌速度等闪蒸过程参数对硫酸镁晶体产品粒度的影响及其影响趋势。在单因素实验的基础上,通过正交实验确定硫酸镁溶液在实验考察范围内的闪冷结晶结晶优化结晶工艺:硫酸镁初始浓度为39.9%,闪冷压力为40.0 kPa,搅拌速率为350 r/min;其中闪冷压力为结晶粒度主要影响因素。

Industrial magnesium sulfate wastewater is usually treated by evaporation concentration combined with flash crystallization.In order to solve the problem of small particle size product obtained from flash crystallization process of magnesium sulfate wastewater containing a small amount of calcium,the flash crystallization process of magnesium sulfate was investigated systematically.The solubility of magnesium sulfate in 0.1%(mass fraction)calcium sulfate solution was determined by static method,and determined the crystal form of equilibrium solid phase at different temperature.Meanwhile,the single factor method was used to investigate the process parameters such as effect of initial concentration,vacuum and stirring rate on the average particle size of magnesium sulfate crystals and its trend.On the basis of single factor experiments,the optimized crystallization condition of flash crystallization was determined through orthogonal experiment:initial concentration of magnesium sulfate was 39.94%,vacuum was 40 kPa and stirring rate was 350 r/min,vacuum is the main influencing factor.