Investigation of kinetics and mechanism of priceite leaching in sulphuric acid solutions

The leaching kinetics and mechanism of priceite having the formula of 4CaO5B2O37H2O was investigated in sulphuric acid solutions. For the dissolution process, the effects of reaction temperature, sulphuric acid solution concentration, solid/liquid ratio, particle size, and stirring speed were investigated as effective parameters for the experiments. The experimental data indicated that the dissolution rate increased with the increasing reaction temperature, the decreasing particle size, and the solid/liquid ratio. The conversion rate increased up to 1.0 mol/dm3 with the increasing acid concentration, and then decreased with the increasing acid concentration over concentrations of 1 mol/dm3. It was also determined that the stirring speed had no significant effect on the dissolution rate. The dissolution process of priceite in sulphuric acid solution was tested with regard to heterogeneous and homogeneous reaction models, and it was found that the dissolution rate was controlled by first order pseudo-homogeneous reaction model. The activation energy of the dissolution process was determined as 26.07 kJmol-1. The results were evaluated graphically and statistically. The experimental data were found to fit well with the mathematical model.