THE FERRIC FLUOSILICATE LEACHING OF LEAD CONCENTRATES .1. KINETIC-STUDIES

A new hydrometallurgical leaching process, which dissolves lead concentrates with acidified ferric fluosilicate solution, has been investigated for the selective extraction of lead and zinc from lead concentrates containing galena. The leaching of the Pine Point lead concentrate by ferric fluosilicate solutions was studied under various experimental conditions in the temperature range 20-degrees-C to 95-degrees-C. Temperature had a pronounced effect on the dissolution of the concentrates. The rates of lead leaching are very rapid over the temperature range 38-degrees-C to 95-degrees-C. The kinetics of zinc extraction are much lower than those of lead extraction. The reaction rates for the dissolution of galena were found to be controlled by surface chemical reaction. The apparent activation energy of the leaching reaction was calculated to be 62.1 kJ/mol. The initial concentrations of Pb2+, H+, and Fe3+ in the lixiviant do not have a significant effect on the rate or extent of lead extraction under the experimental conditions in this study.