Determination of the Optimum Conditions for the Dissolution of Colemanite in H3PO4 Solutions

The Taguchi method is an engineering design optimization methodology that improves the quality of existing products and processes and simultaneously reduces their costs very rapidly, with minimum engineering resources and development man hours. In this study, this method was utilized to investigate the effect of various parameters for determining the optimum dissolution conditions of colemanite (Ca2B6O11·5H2O) in phosphoric acid solutions. The parameters investigated were the acid concentration, particle size, stirring speed, and reaction time. The most significant parameters affecting the solubility were the reaction time and particle size, whereas the acid concentration and stirring speed had a lesser effect. The optimum dissolution conditions were determined as follows: reaction time, 12 min; particle size, 2.4 mm; acid concentration, 2.7 M; stirring speed, 450 rpm; reaction temperature, 94 (degree)C; solid-to-liquid ratio, 0.25. Under these conditions, it was found that boron extraction from colemanite ore was 100%.