采用等温溶解平衡法研究了三元体系KH₂PO₄-KCl-H₂O、NH₄H₂PO₄-NH₄Cl-H₂O在283.15 K时的相平衡,并用湿渣法与X射线衍射相结合的方法鉴定了平衡固相的组成与结构。结果表明,三元体系KH₂PO₄-KCl-H₂O和NH₄H₂PO₄-NH₄Cl-H₂O为简单共饱和型,无固溶体或加合物形成,每个相图包含1个不变点、2条单变量曲线和3个结晶区。运用Pitzer电解质溶液理论计算了简单三元体系KH₂PO₄-KCl-H₂O、NH₄H₂PO₄-NH₄Cl-H₂O的饱和溶解度数据,结果表明,KH₂PO₄-KCl-H₂O体系的相对平均偏差为0.046,均方根偏差为0.29,NH₄H₂PO₄-NH₄Cl-H₂O体系的相对平均偏差为0.044,均方根偏差为0.31,溶解度理论计算结果与实验值基本一致。

The phase equilibrium of KH₂PO₄-KCl-H₂O and NH₄H₂PO₄-NH₄Cl-H₂O at 283.15 K was determined by using isothermal dissolution equilibrium method.The composition and structure of equilibrium solid phase were identified by analy-sis of wet slag and X-ray diffraction.Results showed that the ternary systems KH₂PO₄-KCl-H₂O and NH₄H₂PO₄-NH₄Cl-H₂O were simple cosaturated,and no solid solution or adduct was formed.Each phase diagram contained one invariant point,two univariate curves and three crystallization regions.The saturated solubility data of simple ternary systems KH₂PO₄-KCl-H₂O and NH₄H₂PO₄-NH₄Cl-H₂O were calculated by Pitzer electrolyte solution theory.Results showed that the relative average deviation and the root mean square error of KH₂PO₄-KCl-H₂O system were 0.046 and 0.29 respectively,and the relative average deviation and the root mean square error of NH₄H₂PO₄-NH₄Cl-H₂O system were 0.044 and 0.31 respectively.The calculated value agreed with the experimental value well.