Bioleaching of copper from samples of old flotation tailings (Copper Mine Bor, Serbia)

Abstract

Bioleaching of samples taken from depths of 10, 15, and 20 m from old flotation tailings of the Copper Mine Bor was conducted in shaken flasks using the extremely acidic water of Lake Robule as lixiviant. The yields of copper after five weeks of the bioleaching experiments were 68.34±1.21 % for the 15-m sample, 72.57±0.57 % for the 20-m sample and 97.78±5.50 % for the 10-m sample. The obtained results were compared to the results of acid leaching of the same samples and it was concluded that bioleaching was generally more efficient for the treatment of samples taken from depths of 10 and 20 m. The content of pyrite in the 20-m sample, which contained the highest amount of this mineral, was reduced after bioleaching. The benefits of this approach are recovery of substantial amounts of copper, reducing the environmental impact of flotation tailings and the application of abundant and free water from the acidic Robule Lake as lixiviant. The obtained results showed that bioleaching could be more efficient than acid leaching for copper extraction from flotation tailings with higher sulfide contents.