Kinetics of Coal Desulfurization in An Oxidative Acid Media

Abstract

Tests were carried out for determining pyrite dissolution present in carbon in an aqueous media by using sulfuric acid and hydrogen peroxide as oxidant. The main objective is the evaluation of an oxidative treatment in acid media focused on the elimination of pyrite from coal. The influence of several parameters such as temperature, acid, and hydrogen peroxide concentrations were investigated. It was found that the dissolution curves for pyritic sulfur follow the kinetic model of the shrinking core model, with diffusion through the solid product of the reaction as the controlling stage. Additional tests show the preferential release of iron from pyrite leaving a reacted “polysulfide” or “metal deficient” layer. Results also indicate that, in aqueous solutions of 0.5 M of H2SO4 at 60°C and with an increase in hydrogen peroxide concentration, pyrite dissolution increases around 50%. The results also show the peroxide degradation due to the presence of iron ions and the coal matrix.