Phase Equilibria in the Quaternary Systems KCl–PbCl2–ZnCl2–H2O and MgCl2–PbCl2–ZnCl2–H2O at 373 K

In this work, the method of isothermal dissolution equilibrium was applied to investigating the phase equilibria of quaternary systems KCl–PbCl2–ZnCl2–H2O and MgCl2–PbCl2–ZnCl2–H2O at 373 K throughout the entire concentration range. Isothermal solubility and water content diagrams were constructed based on the measured solubility of components and the coexisting solid phase, respectively. The experimental results indicate that the phase diagram of the quaternary system KCl–PbCl2–ZnCl2–H2O at 373 K consists of three invariant points, seven univariant isothermal solubility curves, and five single solid-phase crystalline regions corresponding to KCl, PbCl2, KCl·2PbCl2, 2KCl·ZnCl2, and ZnCl2. It is shown that the phase diagram of the quaternary system MgCl2–PbCl2–ZnCl2–H2O at 373 K is made up of two invariant points, five univariant isothermal solubility curves, and four single solid-phase crystalline regions corresponding to MgCl2·6H2O, PbCl2, MgCl2·ZnCl2·5H2O, and ZnCl2.