Kinetics of salt roasting of chalcopyrite using KCl

The process of salt roasting appears to be very promising because it lowers the reaction temperature and leads to water soluble chloride salt. This paper presents the kinetics of salt roasting of chalcopyrite using KCl as the chlorinating agent. Isothermal thermogravimetric studies were carried out in the temperature range of 523-773 K under oxygen, static air and argon atmospheres. It is observed that the weight gain is more in the presence of oxygen than in static air. Weight loss is observed when salt roasting is carried out under an inert atmosphere. It is deduced that the reaction is chemically controlled at temperatures below 600 K both under static air and oxygen atmosphere. At higher temperatures, the process is not thermally activated. The weight gain decreases with increase in temperature because of a change in the chemistry of the process. The roasting experiments carried out in a horizontal electric tube furnace under an oxygen atmosphere shows that up to 96% Cu can be recovered from the chalcopyrite by salt roasting with KCl and subsequent water leaching. (C) 2000 Elsevier Science B.V. All rights reserved.