A revised description of the binary CaCl2-H2O chemical system up to solution-mineral equilibria and temperatures of 250 °C using Pitzer equations. Extension to the multicomponent HCl-LiCl-NaCl-KCl-MgCl2-CaCl2-H2O system
Arnault Lassin, Laurent André
Abstract
Calcium chloride is a highly soluble chemical compound involved in variable amounts in many natural and industrial environments. The description of its chemical properties and mineral-solution equilibrium conditions must cover a wide range of temperatures and chemical compositions, including saline solutions. This article reports an improved model for the thermodynamic accurate description of the CaCl 2 -H 2 O chemical system according to the Pitzer formalism from 25 to 250 °C, over the whole concentration range between pure water and the solubility of salts (up to 30 M). It accounts for the aqueous speciation of the CaCl 2 electrolyte, according to the partial molar properties of the Ca 2+ , CaCl + , CaCl 2 0 and Cl − aqueous species described by the HKF theory. The numerical stability, resulting from the lowered ionic strength in comparison to full dissociation, facilitates the development of temperature-dependent models for ternary systems containing the main major cations: H + , Li + , Na + , K + , and Mg 2+ .