Prediction of phase equilibria in multicomponent water-salt systems by means of translation method

Abstract

The translation method which can produce all the geometrical figures and closed phase equilibria diagram for multicomponent water-salt systems was described. The phase equilibria in quinaryNaCl - KCl -MgCl2 - CaCl2 - H2O (25°C) system which is an important part of the more complex oceanic Na, K, Mg, Ca//Cl, SO4- H2O system were determined using translation method. Three invariant points of quadruple saturation, tenmonovariant curves of triple saturation and twelvedivariant fields of double saturation salts were identified in the system. Two of the curves extend between the quinary invariant points while the other eightare generated from extension of the relevant quaternary invariant points into the quinary composition. A total phase equilibria diagram for the quinary NaCl - KCl - MgCl2 - CaCl2 - H2O system at 25°C was constructed on the basis of obtained results. The diagram was fragmented into divariant fields of common crystallization of two salts. A good agreement was observed between the results obtained in this work and the available data in literature.