Kinetics Study of Thorium Silicate Dissolution in Sulfuric Acid Media

This study was conducted to investigate the kinetics of dissolution of pure thorium silicate (thorite mineral). This compound was synthesized by the hydrothermal method with a purity of 97.8%. The parameters affecting the dissolution kinetics of synthetic thorium silicate were optimized. The agitation speed of 450 rpm, sulfuric acid concentration of 4 M, and temperature of 100°C were determined as optimal conditions. According to scanning electron microscopy (SEM) images, as well as dynamic light scattering (DLS) and Brunauer–Emmett–Teller (BET) analyses before and after dissolution, the dissolution kinetics model of thorium silicate was determined based on the shrinking particle model. Using the Arrhenius equation, the activation energy was calculated to be 78.41 kJ/ mole. The thorium silicate dissolution mechanism was identified based on chemical control reaction. The reaction order of the concentration of sulfuric acid at different temperatures was 1.64 ± 0.44.