In this study, the solubility of zinc sulfide has been collected from the literature at pH 2 to 11, temperature 23 to 250 °C, pressure 0.6 to 150 bar, and ionic strength 0 to 4.6 m. A solubility model has been developed based on the combination of Pitzer theory calculated activity coefficient and speciation of the Zn-HS-OH-Cl aqueous system. In total, around 230 solubility data were collected as the input database, the model was fitted in Matalab 2020a with the particle-swarm optimization. The updated model is able to predict the ZnS solubility saturation index (SI) with 95% confidence interval 0.04 SI unit, which suggested good accuracy under model conditions. Due to the extremely low solubility of the ZnS itself, these errors correspond to only around 0.07 ppm of [Zn(II)], which is less than the error of measurement for field samples. For all pH conditions, Zn-HS complexes and Zn-Cl complexes have strong influence on the aqueous soluble zinc solubility. This new model with accurate ZnS solubility prediction will help field operators to better control the ZnS scaling and corrosion problem.

Subject
Stability, Ion speciation, Modeling, Solids, Solubility, Acidity, Constants, Ion concentrations, Saturation index, Brines, Sulfides, Zinc, High temperature
Keywords:
zinc sulfide, scale, solubility modeling, high temperature, high pressure, high TDS, ion complexes
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2022
Association for Materials Protection and Performance (AMPP)
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