Influência de tamanho das partículas na cinética de reação entre scheelita e HC1.

Abstract

The present work aims to study the influence of particle size on the scheelita leaching reaction with hydrochloric acid and to test the Shrinking model. Core "with conversion rate control by the thin layer of the reaction product. The reaction kinetics: CaW04 (s) + 2HC1 (aq) H2W0 (s) + Ca C12 (aq) was followed using a glass bench reactor The double wall wall together with a thermostat circulator obtaining isothermal and total mixing conditions From the Scheelita de Santa Luzia (Pb) concentrates, particle samples of average diameters 40, 81,115 and 163 µm were prepared. microphotographs of these samples.The conversion of Scheelita with time was determined volumetrically in Ca ++ terms reacted at temperatures 40, 60 and 80 ° C and HCl concentration being 2M. Leaching kinetics are interpreted in terms of the Shrinking Core model: 1-2 / 3 • x- (1-x) 2/3 = Kp-t, where x, Kp, t represent conversion, parabolic constant and reaction time respectively. The relationship between the Scheelite conversion in terms of the parabolic constant (Kp) of the Shrinking Core model and the Initial mean particle diameter (dp) in the range 40 to 163 ym was found to be: Kp = (dpo) -0.65. The activation energy (Ea) of Scheelita leaching with HCl was calculated equal to 11.3k Cal / mol.