Kinetics and Mechanism of Palladium Pressure-Cyanide Dissolution

Abstract

At room temperature and pressures, the reaction between sodium cyanide and platinum group metals (PGMs) does not occur because of poor kinetics. However, at elevated temperatures, PGMs can be leached by sodium cyanide like the reaction of gold. However, few rate expression which describe the leaching of Palladium in cyanide solution has been developed. In this paper, the rate of Palladium dissolution was measured in pressure clear cyanide solution using a Palladium rotating disk. The data at different rotation speed, cyanide concentrations, temperature and oxygen pressure are obtained. The dissolution rates were independent of rotation speed for oxygen-saturated solutions between 100-400rpm. With increasing temperature the dissolution rate is increased. With increasing cyanide concentration and oxygen pressure, the dissolution rate first increased to a maximum value and then decreased.