采用等温溶解平衡法研究了四元体系Na+//Cl-,SO42-,NO-3-H2O在5、0、-5与-15℃下的相平衡关系。结果表明,4个温度下体系无复盐形成,平衡相图的构型基本一致;平衡相图均由3个结晶区(Na2SO4·10H2O、Na Cl和Na NO3)、3条单变量曲线(Na Cl-Na2SO4·10H2O、Na Cl-Na NO3、Na NO3-Na2SO4·10H2O)及1个共饱点(Na Cl-Na NO3-Na2SO4·10H2O)组成;4个温度下的平衡相图相比,随着温度的下降Na2SO4·10H2O结晶区不断扩大,Na Cl和Na NO3结晶区相对缩小;与该体系常温下的平衡相图相比,由于无复盐形成,低温下的相图大为简化。 The isothermal equilibrium method was used to study the phase equilibrium of the quaternary system Na + // Cl-, SO42- and NO-3-H2O at 5, 0, -5 and -15 ℃. The results show that there is no complex salt formed at four temperatures and the equilibrium phase diagram is basically the same. The equilibrium phase diagram consists of three crystallization zones (Na2SO4 · 10H2O, NaCl and NaNO3), three univariate curves (Na Cl-Na 2 SO 4 · 10H 2 O, Na Cl-Na NO 3, Na NO 3 -SO 4 SO 4 · 10H 2 O) and one co-saturate (Na Cl-Na NO 3 -NaSO 4 · 10H 2 O). Compared with the equilibrium phase diagram at 4 temperatures, With the decrease of temperature, the crystallization zone of Na2SO4 · 10H2O is expanding continuously, and the crystallization zones of NaCl and NaNO3 are relatively reduced. Compared with the equilibrium phase diagram of the system at room temperature, the phase diagram at low temperature is greatly simplified because of no double salt formation.