Dissolution of Colemanite in Aqueous Solutions Saturated with Both Sulfur Dioxide (SO2) Gas and Boric Acid

Boron compounds that are produced from boron ores are important industrial materials. In this report, an alternative method for the formation of boric acid obtained via the reaction between colemanite and sulfuric acid in aqueous media was studied. For this purpose, the kinetics and mechanism of the dissolution of colemanite were investigated in saturated boric acid solutions that were saturated with SO2 gas. In the experiments, the particle size, solid-to-liquid ratio, stirring speed, and temperature were chosen as parameters. As a result, the conversion rate increased as the particle size and solid-to-liquid ratio each decreased and the temperature increased; however, the effect of stirring speed was very minimal. In addition, the conversion rate was determined to fit the Avrami model, and the activation energy of the process was estimated to be 50.15 kJ/mol. The integrated rate equation for this conversion was determined to be as follows: -ln(1 - X) = (1.26 × 105)[SO2]D-1.52(S/L)-0.14 e-6031/Tt0.73.