Dissolution kinetics of pyrite ore by hydrochloric acid

Abstract

Dissolution kinetics of pyrite ore (sourced from Nigeria) by hydrochloric acid were investigated. The elemental composition was determined by Inductively Coupled Plasma-Mass Spectrometry, while the mineral phase was characterized by powder X-ray diffractometry. The major elements in the ore were Fe (42.76 %), S (31.89 %), Si (7.35 %) and Zn (4.76 %). The minor elements consisted of Pb (2.63 %), Ag (1.39 %), and Mn (0.03 %), whi-le traces of Ca, Mg, V, Sb, Ni and Ra were also found. The major compounds in the ore were FeS2 and Fe2 (SO4)3, with associated mineral phases of ¥á-SiO2, Mn3O5, PbS and ZnS. The effects of HCl concentration, tem-perature and particle size on the dissolution rate indicated that about 76.4 % of the ore of < 0.1 mm particle size was dissolved at 80 ¢ªC and stirring rate of 360 rpm. The dissolution rate was also dependence on hydrogen ion concentration of the reaction system. Activation energy of 38.8 kJ mol-1 and Arrhenius constant of 3.00 s-1 were obtained for the dissolution, confirming the rate controlling mechanism to be diffusion controlled surface chemi-cal reaction