杂质离子对MgCl2和CO2反应-萃取-醇析耦合过程的影响

Effects of impurity ions on coupled reaction-extraction-alcohol precipitation process of MgCl_2 and CO_2

通过反应-萃取-醇析耦合过程,将Mg Cl2和CO_2制备成碳酸镁和氯化氢气体是盐湖老卤资源化利用的有效途径。系统地研究了老卤中Na^+、K^+、Ca^(2+)对MgCl_2和CO_2反应-萃取-醇析耦合过程得到的固体产物晶型晶貌的影响。结果表明,Na^+和K^+对耦合过程的影响相似,固体产物均为高纯棒状三水碳酸镁(MgCO_3·3H_2O),且Na^+和K^+均能选择性吸附在MgCO_3·3H_2O晶体的轴面(1 0 1),阻碍该晶面的生长,使得棒状MgCO_3·3H_2O直径变小;Ca^(2+)对反应-萃取-醇析耦合过程有不利的影响,由于CaCl_2能参与反应,生成球状无定形纳米钙镁碳酸盐,使得三水碳酸镁纯度降低。

The preparation of nesquehonite（MgCO_3·3H_2O） and hydrogen chloride by MgCl_2 and CO_2 based on a coupled reaction-extraction-alcohol precipitation process is an effective way for the comprehensive utilization of brine. The effects of impurity ions Na^＋, K^＋ and Ca^（2＋） in brine on the morphology of the solid product obtained in the coupled reaction-extraction-alcohol precipitation process are investigated systematically. The results indicate that Na^＋ and K^＋ have a similar influence on the coupled process. The products are rod-like high purity MgCO_3·3H_2O when Na^＋ and K^＋ are added. Moreover, Na^＋ and K^＋ can be selectively absorbed onto the axial face（1 0 1） of MgCO_3·3H_2O, that will hinder the growth along the（1 0 1） direction and resulting a decrease in the diameter of MgCO_3·3H_2O. Ca^（2＋） shows a negative effect on the coupled process. The added impurity CaCl_2 can react with CO_2 and form spherical amorphous nano Mg/Ca-carbonate, which will decrease the purity of the solid products.