DISSOLUTION KINETICS OF PYRITE ORE BY HYDROCHLORIC ACID

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 ¥a-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