Sulphation Kinetics of Zinc Sulphide with Ammonium Sulphate and Ammonium Bisulphate

Abstract

Studies on the kinetics of sulphation of zinc sulphide with ammonium sulphate have been carried out. The influence of temperature (448 K to 873 K), reaction atmosphere such as oxygen, nitrogen and air, amount of ammonium sulphate up to 330% stoichiometry and duration of roasting (up to 120 min) have been studied.The activation energy values using the Arrhenius equation were 84 and 36 kJ/mol in the temperature ranges of 448 K–548 K and 548 K–623 K respectively indicating two separate reaction mechanisms. To confirm the two reaction mechanisms, similar studies were carried out using ammonium bisulphate in the same temperature range. The activation energy was 42 kJ/mol which agreed well with that obtained in case of ammonium sulphate at higher temperature range studied. The activation energy values based on initial rates were 29 and 17 kJ/mol with ammonium sulphate and ammonium bisulphate respectively. Sulphation increased with addition of ammonium sulphate and ammonium bisulphate, more rapidly with the latter. Sulphation reaction of zinc sulphide with these two reagents were of first order.