Sulphation of chalcopyrite with steam and oxygen in the presence of some additives

Abstract

It has been observed that the sulphides undergo weathering process to produce the metal sulphates at a very slow rate. Therefore, higher conversion to sulphates may be achieved by creating aggressive conditions at higher temperature similar to that of weathering process by using a mixture of steam and oxygen. The results obtained by this method shows a conversion of 82.32% copper sulphate from a chalcopyrite concentrate at 773 K in presence of 10% Fe2O3. The role of different additives like ferric oxide, ferrous sulphate and sodium sulphate on sulphation of chalcopyrite with steam and oxygen was investigated. The copper sulphate formation without any additive was found to be 71.9% whereas the values were 84.4 and 86.5% with 10% Na2SO4 and 20% FeSO4 respectively at 773 K. The kinetics of the sulphation with additives has also been studied in the fixed bed in the temperature range 673-773 K in absence of external mass transfer effect due to particle size, how rate, etc. The reaction was found to be topochemical in nature. The activation energy values using the Arrhenius equation plots were obtained as 29.2 kJ/mol with 10% Fe2O3, 23.57 kJ/mol with 10% Na2SO4 and 21.03 kJ/mol with 20% FeSO4 in the above temperature range. The sulphated products were characterized by XRD and SEM studies.