25℃下Na+,K+,Mg2+//Cl-,SO2-4,NO-3,H2O体系液固相平衡

摘要

应用等温溶解平衡法,研究了Na+,K+,Mg2+//Cl-,SO2-4,NO-2,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+, Mg2+//Cl-, S024- , NO-3, H2 0 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 · 6H20, NaCl, MgCl2 · 6H20,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.