Acidic and Ammonium Sulphate Leaching of Historic Copper Tailings from Copperbelt Province, Zambia

Acid and ammonia leachingLeaching was carried out on old froth flotation copper tailingsCopper tailings from the Copperbelt Province in ZambiaZambia. The following parameters were studied: type of acid, leachingLeaching time, residence time, pulp density, and temperatureTemperature. Over 80% of Cu was extracted during leachingLeaching with sulphuric and hydrochloric acid. On the other hand, leach efficiency for manganeseManganese was around 70%. By comparison, sulphuric acid yielded a slight higher leach efficiency for copper and manganeseCopper and manganese than hydrochloric acid. LeachingLeaching time and temperatureTemperature had a little influence on the recoveryRecovery of copperCopper under acidic leachingLeaching. By comparison, leach efficiency of manganeseManganese was more dependent on the time than copperCopper. The optimum time was four hours for ammonia leachingLeaching. Analysis of the leach solution with ICP-OES showed that ammonia leachingLeaching was more selective for copperCopper than manganeseManganese.