Solubility Prediction for the Reciprocal Quaternary System (Li~+, Mg~(2+)//Cl~-, (SO_4)~(2-)-H_2O) at 273.15 K Using Pitzer Ion-interaction Model

摘要

Solubilities of the reciprocal quaternary system (Li~+, Mg~(2+)//Cl~-, (SO_4)~(2-)-H_2O) at 273.15K were calculated using Pitzer and its extended HW model. The values of the Pitzer single-salt parameters β~((0)), β~((1)), β~((2)) and C~Φ for LiCl, MgCl_2, Li_2SO_4, and MgSO_4, the mixed ion-interaction parameters θ_(Li,Mg), θ_(Cl,SO_4), Ψ_(Li,Mg,Cl), Ψ_(Li,Mg,SO_4), Ψ_(Li,Cl,SO_4) and Ψ_(Mg,Cl,SO_4), and the Debye-Huckel parameter A~Φ in the system at 273.15K were derived either temperature-dependent equation or through fitting solubility data of the ternary system by multiple linear regression method. Based on the Janecke indexes, the phase diagram was plotted. This study affords the necessary parameters for solubility predictions of complicated systems and establishes a theoretical basis for the separation of these valuable minerals from salt lake brine.