A Taguchi Optimization Study about the Dissolution of Colemanite in Ammonium Bisulfate (NH4HSO4) Solution

In this study, the optimum conditions of the dissolution of colemanite (2CaO.3B2O3.5H2O) ore in ammonium bisulfate (NH4HSO4) solution were examined by using Taguchi fractional design methods, and an alternative reactant for boric acid extraction process from colemanite ore was specified. The studied parameters and optimum conditions for the dissolution process were the following; reaction temperature: 50˚C, solid/liquid ratio: 0.1 g/mL, particle size: -80 mesh, mixing speed: 600 rpm, and reaction time: 25 minutes. Particle size, mixing speed, and reaction time had the most significant effect on dissolution when compared to the others. Accordingly, the dissolution efficiency of colemanite was found to be 99.54% under optimum conditions and using NH4HSO4 as a solvent enabled the selective separation of boron from the colemanite ore. The ammonium sulphate formed as a by-product was converted into NH4HSO4 by the addition of the appropriate stoichiometric amount of sulfuric acid and fed back into the dissolution vessel.