Bioleaching of Sulphide Minerals with <i>Sulfobacillus acidophilus</i> at 45°C

Abstract

Copper sulphide ore bioleaching processes are currently under full development in Chile and worldwide, for treatment of: secondary sulphide in heaps [1], low-grade ores in dumps, and concentrates in reactors at high temperatures [2]. Abundant knowledge is available in the literature and great experience has been gathered about the behavior of mesophilic microorganisms and their application in bioleaching of sulfides in heaps and dumps [, as well as, about the behavior of extreme thermophilic microorganisms in reactors [. However, there is little information about the behavior of some moderately thermophilic microorganisms in the dissolution of chalcopyrite and pyrite at 45oC [. This is the case ofS. acidophilus, a gram-positive rod shaped that often forms endospores and grow at temperature optima, generally between 45 and 55°C. It has been characterized as a chemolithoheterotrophic bacteria that obtains energy from the oxidation of ferrous iron or from reduced sulfur compounds and that utilizes yeast extracts as a carbon source [.S. acidophiluswas isolated by Golovacheva and Karavaiko [ and described by Norris et al. [. Limited literature exists about its participation in bioleaching processes. In this work, we present experimental results obtained from the bioleaching of chalcopyrite and pyrite withS. acidophilusat 45°C, and compare them with those obtained withAt. ferrooxidansat 30°C.