Measurements and predictions of mineral solubilities in the quaternary systems NaCl plus KCl + SrCl2 + H2O, NaCl + MgCl2 + SrCl2 + H2O and KCl + MgCl2 + SrCl2 + H2O at 308 K

This paper describes the measurements and predictions for mineral solubilities in the quaternary systems NaCl + KCl + SrCl2 + H2O, NaCl + MgCl2 + SrCl2 + H2O, KCl + MgCl2 + SrCl2 + H2O and subsystem MgCl2 + SrCl2 + H2O at 308 K in detail. The isothermal dissolution equilibrium method was used to determine the solubility of each salt in systems experimentally. Each stable phase diagram was constructed according to the measured results. The ternary system MgCl2 + SrCl2 + H2O has two invariant points, three solubility curves and three crystallization regions (MgCl2 center dot 6H(2)O, SrCl2 center dot 2H(2)O and SrCl2 center dot 6H(2)O). There is one invariant point, three solubility curves and three crystallization regions (NaCl, KCl and SrCl2 center dot 6H(2)O) in the quaternary system NaCl + KCl + SrCl2 + H2O. Two invariant points, five solubility curves and four crystallization regions (NaCl, MgCl2 center dot 6H(2)O, SrCl2 center dot 2H(2)O and SrCl2 center dot 6H(2)O) are included in the quaternary system NaCl + MgCl2 + SrCl2 + H2O. In the quaternary system KCl + MgCl2 + SrCl2 + H2O, the double salts KCl center dot MgCl2 center dot 6H(2)O were found as its ternary system KCl + MgCl2 + H2O, thus this quaternary system contains three invariant points, seven solubility curves and five crystallization regions (KCl + MgCl2 center dot 6H(2)O + KCl center dot MgCl2 center dot 6H(2)O + SrCl2 center dot 2H(2)O + SrCl2 center dot 6H(2)O). Using the fitted mixing parameter Psi(Mg),(Sr),(Cl) and the Pitzer parameters available in literatures, the phase equilibria of four systems listed above were predicted with the Pitzer ion interaction model. The calculations are in adequate agreement with the experimental values.

Automated summary

This paper provides detailed measurements and predictions of mineral solubilities in different salt systems. The phase diagrams were constructed based on experimental results, and the Pitzer ion interaction model was used to predict the phase equilibria. The predicted values were in good agreement with the experimental data.