ASSESSMENT OF A NIGERIAN CHALCOPYRITE ORE DISSOLUTION IN SULFURIC ACID MEDIUM

Abstract

This paper presents a study of dissolution kinetics of a Nigerian chalcopyrite ore in sulfuric acid lixiviant. The effects of acid concentration, temperature and particle diameter on the dissolution rates of chalcopyrite ore have been examined. The dissolution rates are significantly influenced by increase in temperature, hydrogen ion concentration [H+], and decrease in particle diameter. The experimental data for the dissolution rate have been analyzed with the shrinking core model which shows the rate controlling step for the dissolution of chalcopyrite ore occurs via surface chemical solution. With 4 M H2SO4 solution, about 91.6% of 10 g/L chalcopyrite ore at 80 degrees C was dissolved within 120 min using -90+75 rtm particle diameter. The reaction order with respect to hydrogen ion concentration was found to be 0.57 with correlation coefficient 0.968. The calculated activation energy, (Ea) value of 44.9 kJ/mol for the dissolution process was established. However, the SEM morphology of the residues from leaching process showed that about 8.4% of the initial solid material contained admixtures of Fukuchilite (Cu0.42Fe0.58S2), and elemental sulphur (S degrees) and are formed around the shrinking core of the unreacted material.