Kinetics of sulfuric acid leaching of low-grade zinc silicate ore

The results of a leaching kinetics study of low-grade zinc silicate ore with sulfuric acid are presented. Effect of ore particle size, reaction temperature, and acid concentration on zinc dissolution rate were determined. The results obtained show that leaching of about 94% of zinc is achieved using - 200 + 270 mesh ore particle size at a reaction temperature of 70 degrees C for 180 min reaction time with 10% sulfuric acid concentration. The solid:liquid ratio was maintained constant at 1:20 g/ml. Leaching kinetics indicate that diffusion through the product layer is the rate controlling process during the reaction. The activation energy was determined to be about 3.2 kcal/mol, which is characteristic for a diffusion-controlled process. (C) 2000 Elsevier Science B.V. All rights reserved.