氟硅酸化学沉淀法净化萃余酸中的镁

Using H_2SiF_6 to Precipitate Magnesium from Raffinate of Wet-process Phosphoric Acid Purification by Chemical Precipitation

通过二次回归正交设计，实验研究了化学沉淀法净化未经浓缩的革余酸中镁离子的工艺条件，对氟硅酸用量、苹余酸水去除量、反应温度和反应时间四个因子进行了研究。实验结果表明：当氟硅酸用量为95．71g，除水量为80．41g，反应温度为36．02℃，反应时间为45．03min时，可使镁离子去除率达到最佳值，达到生产优等DAP的磷酸要求；实验得到的镁去除率（y）与氟硅酸用量（z1）、除水量（z2）、反应温度（z3）和反应时间（z4）的模型预测方程为：y=59．1785—0．541156z1＋0．425071z2—0．660951z3-1.635317z^21＋1．768750z1z2-6．392974z^22＋1．011250z1z3—0．9787502223—0．611140z^23-1．106885z^24.

The second-order orthogonal regression design was used to study the process of Mg^2＋ precipitation from raffinate acid （raffinate of wet-process phosphoric acid purification） which was not concentrated by chemical precipitation, and the factors of H2SiF6 usage, water evaporation amount from raffinate acid , reaction temperature and residence time were studied respectively. The experimental results indicated that the Mg^2＋ removed ratio would be optimal and reached the demand of superior DAP production when the H2SiF6 usage is 95.71g, water evaporation amount is 80.41g, reaction temperature is 36.02 and residence time is 45.03 min. The mathematics model to forecast the Mg^2＋ removed ratio from raffnate acid was obtained among H2SiF6 usage and water evaporation amount, reaction temperature and residence time, and the factors＇ effects can use below formula to explain.y=59.1785-0.541156z1＋0.425071z2-0.660951z3-1.635317z^21＋1.768750z1z2-6.392974z^22＋1.011250z1z3-0.9787502223-0.611140z^23-1.106885z^24.