25℃下Na^+,K^+,Mg^(2+)//Cl^-,SO_4^(2-),NO_3^-,H_2O体系液固相平衡

Liquid-Solid Equilibrium of Na^+,K^+,Mg^(2+)//Cl^-,SO_4^(2-),NO_3^-,H_2O System at 25 ℃

应用等温溶解平衡法,研究了Na+,K+,Mg2+//Cl-,SO24-,NO3-,H2O六元体系在25℃的氯化钠饱和溶液中的相平衡关系,测定了溶解度,并绘制出相应的相图.研究结果表明,在25℃时,该体系在氯化钠饱和溶液中存在8种复盐,有15个二盐结晶区,25个零变量点;其中只有1个共结点,为Mg(NO3)2.6H2O,NaCl,MgCl2.6H2O,MgSO4.(1～6)H2O和KCl.MgCl2.6H2O五盐共饱点,其余均为反应点.在此基础上,研究了新疆硝酸盐卤水矿蒸发析盐规律.

Solubilities in the system Na^＋,K^＋,Mg^2＋//Cl^-,SO4^2-,NO^-3,H2O saturated with NaCl were investigated by isothermal method at 25 ℃.According to experimental data,the phase diagram was plotted.In this system,there are 8 double salts,15 regions saturated with two salts,and 25 invariant points.In these invariant points,one is an incongruent point saturated with Mg（NO3）2·6H2O,NaCl,MgCl2·6H2O,MgSO4·（1—6）H2O,KCl·MgCl2·6H2O,and the others are reaction points.Based on these results,the sequence of crystallization of salts from the brine during evaporation process was discussed.