Abstract

Precipitation of silica in concentrated sulfuric acid solutions was studied with laboratory-scale batch experiments. The effects of initial silicic acid concentration, temperature, and sulfuric acid concentration were studied. It was observed also in this work that the high ionic strength of the leaching solution drastically decreased the solubility of silica. The solubility was also studied using Gibbs energy minimization method and Pitzer model using the ChemSheet program. Good agreement was obtained between the model and experimental results. The precipitation reaction of silica was observed to follow a pseudo-first-order rate law. Based on the rate law used, an activation energy of 61.7 kJ mol⁻¹ was estimated. This implies a reaction-controlled mechanism of precipitation.