OXIDATION OF COBALTITE .1. PROCESS MINERALOGY

The control of arsenic is important in oxidation roasting and leaching of cobaltite. Oxidation roasting below 823 K did not show any crystal structural change in cobaltite, but heating to 923 K yielded Go-As-ox ide, whose composition is varied. Direct oxidation of cobaltite to cob alt oxides with traces of arsenic was observed by roasting at 1023 K o r above. The distribution of arsenic within the particles gradually de creased from the outer region to the center of the particles. The arse nic concentration within the particles decreased with the increase of temperature, suggesting temperature dependence on arsenic removal from the lattice of cobaltite. In this article, the process mineralogy of the oxidation of cobaltite is presented at various temperatures. The r esults from X-ray diffraction (XRD) analysis, reflected light microsco pic analysis; and scanning electron microscopic analysis of the roaste d cobaltite concentrates together with a rationalized thermodynamic an alysis are presented.