OXIDATION KINETICS OF SULFIDE COPPER BEARING PELLETS

Abstract

This paper studies the results of investigating oxidation kinetics of pellets from copper concentrate produced by Gaisky GOK under conditions of controlled convective heat and mass exchange at the minimum radiation component of heat transfer between heated (450–700 °С) gaseous oxidant (air) and pellets. It was found that as the air consumption increases, the initial oxidation decelerates though theoretically it was proved that the oxidant contact with pellet surface does not limit the process. The paper includes formulas deduced by the author for calculating the period of pellet heating up to temperature of initial oxidation and heated air. It was determined that the higher mechanical strength of pellets decreases the speed and completeness of pellet oxidation. The positive effect of increased oxidant (air) consumption on the oxidation speed due to the lack of external diffusion slow-down is explained by a shorter pellet heating period. Experimental activation energy (Е = 155,1÷337,1 kJ/mole) is typical for kinetic or transition mode at 450–500 °С and pellet strength 718,1 and 932,0 N, and for diffusion mode (E = 33,3÷57,4 kJ/mole) at 500–700 °С. The ratio of efficient diffusion in active layer pores was calculated for an isometric part of the kinetic curve at 600 °C. The indicated part shows Knudsen diffusion.