四元交互体系Li~＋，K~＋／Cl~－，SO_4^（2－）－H_2O50，7　

A Study on Equilibrium Solubilities in the Quaternary Reciprocal System of Li￣+, K￣+/Cr￣-,at 50℃ and 75℃

采用等温溶解平衡法测定了四元交互体系Ｌｉ～＋，Ｋ～＋／Ｃｌ～－，７５℃的溶解度和平衡溶液的物化性质（密度、粘度、折光率）．该四元交互体系５０，７５℃的溶解度等温图有５个相区：即Ｌｉ＿２ＳＯ＿４·Ｈ＿２Ｏ，ＫＬｉＳＯ＿４，ＫＣｌ，Ｋ＿２ＳＯ＿４，ＬｉＣｌ·Ｈ＿２Ｏ，７条单变量曲线，３个共饱点，其中Ｌｉ＿２Ｏ＿４·Ｈ）２Ｏ＋ＫＣｌ＋ＬｉＣｌ·Ｈ＿２Ｏ为一致零变量点。用我们以往提出的经验公式处理了平衡溶液的密度和折光率，由所测得的溶解度数据，求得了高温和高锂浓度下的电解质溶液Ｐｉｔｚｅｒ模型的离子相互作用参数。计算了各平衡溶液中盐的活度和水的活度。还计算了该四元交互体系２５℃的溶解度，考察了Ｐｉｔｚｅｒ电解质溶液理论在水－盐溶解度计算中的应用。

The eqtiibrium solubilities of title quaternary system were studied at 50,75℃ bythe isothernlal method. The phase diagrams of the system consist of seven solubility branch-es and have five crvstallization fields : KLiSO4, Li2SO4·H2O, KCl,K2SO4, and LiCl·H2O.The first one is the largest. Three invariant points exist in the system : LiCl· H2O +KCl +Li2SO4·H2O,KCl+K2SO4+KLiSO4,andKCl+KLiSO4+Li2SO4·H2O. The first one is acongrLient eutonic point , and the others are incongruent. The ion interaction pararneters ofthe Pitzer model for rnixed electrolyte solution at 50℃ and 75℃ were obtained by fitting thedetermined solubility data. The water activity of the equilibrium liquid, and the solubilityproduct of saIts were calculated. The empirical eqtiations of density and refractive index ofthe solution in relationto to its composition were used to correlate the data. The results arein good agreement.