KINETIC STUDIES OF OXIDATION OF COPPER SULPHIDE

Abstract

Reactions between gases and solids play an important part in many metallurgical processes and the need for understanding the mechanisms involved in these reactions cannot be overemphasized. In the present work, kinetics of oxidation of compacted spheres of synthetic cuprous sulphide in air was studied in the temperature range of 750-95d0C. The reaction was followed by measuring SO2 titrimetrically. The reaction is highly exothermic and the heat generated at the reaction front can influence the kinetics and this 'aspect has been taken into consideration in the present work. The temperature of the sample was measured by using fine Pt..Pt/13% Rh thermocouple wires embedded in the centre of the pellet. The process was found to be topochemical and the heat released at the reacting interphase of the compact manifested itself in rise intemperature of the sample than its surroundings. These temperature differences subsequently levelled off after 2) minutes and remained constant during rest of the experiment. The previous intestigetors '-5 unfortunately failed to recognise the significant contri• bution of the exothermic nature of the reaction towards deciding the true controlling mechanism, therefore, led to conclude that the reaction is chemically controlled. The results obtained are analysed on the basis of heat and mass transfer phenomenon. Systematic study was made by analysing separately the experimental results in well defined two regions. The one is referred as 'Transition Period' or 'non-isothermal' period where temperature of the sample initially overshoots the tempera- tune of surrounding. The second is referred as isothermal period where the temperature differences cease and practi-cally no 'offset' was observed during this period. Attempt was also made to study the effect of certain variables, viz., a flow rate, porosity, pellet die., etc., etc. on the oxidation kinetics of copper sulphide pellets. Transport steps are found to be the rate controlling and in the later case, i.e., the effect of variables is in fair agreement with the work reported earlier l"5