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A COMPREHENSIVE PHYSICOCHEMICAL MODEL OF SYNTHETIC BAYER LIQUORS

Königsberger, E., May, P.M. and Hefter, G.

A physicochemical model based on the Pitzer equations has been developed to represent the thermodynamic properties of synthetic Bayer liquor solutions, consisting of the components NaOH – NaAl(OH)4 – Na2CO3 – Na2SO4 – NaCl – NaF – Na2C2O4 (sodium oxalate) – NaHCOO (sodium formate) – NaCH3COO (sodium acetate) – H2O. The model calculates, in a thermodynamically consistent manner, heat capacities, enthalpies, activity and osmotic coefficients, vapour pressures, boiling point elevations and densities of these solutions as well as the solubilities of gibbsite, Al(OH)3, boehmite, AlOOH, sodium oxalate, and other relevant solid phases in synthetic Bayer liquors over the concentration and temperature ranges of industrial interest. Possible extensions of the model to predict the properties of actual plant liquors and applications to Bayer process simulation will be presented.