Ore column leaching with thermophiles: I, copper sulfide ore

The concentrations of ferrous iron in ore column effluents and the pH of the effluents during the leaching of a copper sulfide ore were followed as an indication of the activity of the microbial populations that were established in the ore columns. The impact of this activity and the release of copper were influenced by addition of ferric iron to the irrigation solution, by imposed anoxic conditions and, particularly at higher temperatures, by precipitation of oxidised iron compounds. Moderately thermophilic, acidophilic actinobacteria appeared to dominate the microbial population at 47–57 °C with a transition to ferrous iron oxidation by thermophilic archaea as the temperature was increased above 60 °C.