화학공학소재연구정보센터
Thermochimica Acta, Vol.370, No.1-2, 141-148, 2001
Non-isothermal thermoanalytical studies on the salt roasting of chalcopyrite using KCl
In an earlier study [1], the isothermal kinetics of salt roasting of chalcopyrite under an oxidizing atmosphere using KCl was studied in the temperature range 523-773 K. The salt roasting reaction was found to be chemically controlled at temperatures below 600 K both under static air and oxygen atmosphere. At higher temperatures, the process was not thermally activated because of a change in the chemistry of the process. In the present study, the salt roasting of chalcopyrite using KCl under oxygen and static air atmosphere was studied by non-isothermal thermoanalytical studies up to 723 K. The effect of salt content, heating rate and particle size on the salt roasting behavior was studied using TG/DTA techniques at a programmed linear heating rate. The TG and DTA studies reveal two distinct chemical processes, one operative up to 620 K and the other from 620 to 723 K. The integral method of Coats and Redfern was used for the treatment of non-isothermal kinetic data. The non-isothermal analysis confirmed the chemical control mechanism at temperatures below 620 K. However, the activation energy for the process derived from non-isothermal thermogravimetric analysis is almost twice as that deduced from isothermal measurements. In the temperature range 620-723 K, the kinetic data still obeys the interfacial reaction control model although the activation energy in this temperature range is very low.