Pilot study: On the distribution of elements throughout the Mount Gunson tailings.

Abstract

Heavy metals copper, lead, zinc, cobalt and nickel released from the mining and processing of copper-bearing sulphide minerals at the Mount Gunson Cattle Grid district in central South Australia, were studied to determine their geochemical behaviour and distribution in near surface environments in three tailings impoundments. The Cattle Grid mine was in operation during 1972 - 1986, producing approximately 7.4 million tonnes of tailings. This study of the tailings showed that oxidation of sulphide minerals in the upper 2m of the tailings; coupled with a system dominated by evaporation, led to the occurrence of water-soluble secondary salts in the oxidation zone, resulting in an average pH of 5. In contrast, element fluctuation within the reduced environment at depths below 2m is a function of mineral, grainsize partitioning upon deposition, grade of ore being mined and the efficiency of the extraction process resulting in an average pH of 8.