Kinetic study of silver leaching from semiconductor waste

Abstract

Semiconductor waste can cause serious problem in term of storage and pollution since its contains high concentration of heavy metals. However, this waste is also one of the potential silver recovery source. During the last decade, recovery has become more favorable in waste treatment. Kinetic study has been performed during leaching process. This study involves non-catalytic reaction of particles with surrounding fluid and shrinking core model approach has been used to describes the actual kinetics of the process. Some parameters were investigated, such as types of leaching agent, HCl and NaCl concentration, liquid to solid ratio and stirring speed as well. Several mathematical models have been selected to represent the actual kinetics. The experimental data was obtained at 200 liquid to solid ratio and 200 rpm of stirring speed using mix solution of 0.5M HCl-3.0M NaCl as leaching medium. From the experiment it was shown that the shrinking core model was able to describe the silver leaching behaviour and indicated that the outward diffusion of silver chloro complex is the rate-controlling step.