Dissolution kinetics of tellurium from gold concentrate during alkaline sulphide leaching

Abstract

Alkaline sulphide leaching was adopted to extract tellurium from tellurium-bearing gold concentrate for the first time. The tellurium leaching kinetics were studied. The influence of average particle size, stirring speed, leaching temperature, Na 2 S concentration, and NaOH concentration on the tellurium extraction were investigated. It was found that tellurium extraction could reach 79.14% under the optimum conditions: 17.77 μm average particle size, 500 r/min stirring speed, 80 g/L Na 2 S concentration, 30g/L NaOH concentration, 80°C leaching temperature, 4:1 liquid to solid ratio, and 180 minutes leaching time. The interface transfer and diffusion through the product layer or insoluble substance layer were the rate-controlling steps. The leaching kinetics equation was established, and the activation energy was 34.384 kJ/mol.