Kinetics of copper dissolution from low grade mine tailings subjected to microwave pre-treatment

The extraction of copper from chalcopyrite contained in mine tailings is investigated. Dry mine tailings of a particle size of 75 μm are used in this study. The leaching process includes pre-heating of the mine tailings in a domestic microwave oven for 6 min followed by leaching with 0.5M sulphuric acid in a water bath at various temperature values and leaching times. The results referring to the effect of the leaching time and the temperature reveal that copper recovery increases slightly with the increase of the factors studied. The microwave pre-heating has no notable effect on the copper dissolution efficiency. Shrinking core models are used to determine the dissolution reaction mechanism. The diffusion through the product layer determined by the shrinking core model is found the rate determining step. The Arrhenius plots are used to determine the apparent activation energy which is found ranging from 7.7 kJ/mol to 22.69 kJ/mol.