Solubility and Solid Phase Composition in Boiling-Temperature Na2CO3-Na2SO4 Solutions -A Modeling Approach

摘要

Scaling by Na2CO3-Na2SO4 double salts constitutes a severe problem in black liquor evaporators.Being able to predict the solubility and solid phase composition of these species would help minimize the adverse effects of scaling.A thermodynamically-based model for predicting the solubility and solid-phase composition for burkeite precipitates was applied to solid solutions of dicarbonate,a carbonate-rich double salt identified in Na2CO3-Na2SO4 precipitates.The model was also used in an attempt to represent the solubility behavior in high-temperature Na2CO3-Na2SO4 solutions containing an additional anion (OH~-and Cl~-).The results agree with the hypothesis of a common ion effect in black liquor-type solutions;no anomalies in the formation and the composition of the solid phase were observed.