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

The results of a leaching kinetics study of low-grade zinc silicate ore wit h sulfuric acid are presented. Effect of ore particle size, reaction temper ature, 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 soli d:liquid ratio was maintained constant at 1:20 g/ml. Leaching kinetics indi cate that diffusion through the product layer is the rate controlling proce ss 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.