Metastable Phase Equilibrium in the Reciprocal Quaternary System LiCl+MgCl2+Li2SO4+MgSO4+H2O at 348.15 K and 0.1 MPa

摘要

The metastable solubilities and the physicochemical properties including density and pH of the reciprocal quaternary system(LiCl+MgCl2+Li2SO4+MgSO4+H2O) at 348.15 K and 0.1 MPa were determined using the isothermal evaporation method.The dry-salt diagram and water-phase diagam were plotted based on the experimental data.There are five invariant points,eleven nnivariant curves,and seven crystallization zones corresponding to hexahydrite,tetrahydrite,kieserite,bischofite,lithium sulfate monohydrate,lithium chloride monohydrate and lithium carnallite.Comparison between the stable and metastable diagrams at 348.15 K indicates that the metastable phenomenon of magnesium sulfate is obvious,and the crystallization regions of hexahydrite and tetrahydrite disappear in the stable phase diagram.A comparison of the metastable dry-salt phase diagrams at 308.15,323.15 and 348.15 K shows that with the increasing of temperature the epsomite crystallization zone disappears from the dry-salt phase diagram of 303.15 K,and a new kieserite crystallization zone is presented at 348.15 K.The density and pH in the metastable equilibrium solution present regular change with the increasing of J(a)necke index J(2Li+),and the calculated densities using the empirical equation agree well with the experimental values.