The Mineralogical Effect on the Mesophilic Bioleaching of Copper from Smelter Dust and Flotation Concentrate

Nowadays, bacteria are widely used to recover copper from waste, ore, and concentrate. It is very important to understand bacterial performance in relation to materials with different mineralogy in order to select appropriate bacteria and improve bioleaching processes with high performance. As a consequence, the aim of this study is to investigate the effect of smelter dust and flotation concentrate mineralogy on copper recovery from the materials using mesophilic bacteria. The effect of processing material mineralogy on biological extraction of copper was investigated using a couple of material with different mineralogy, metallurgical dust and concentrate of Sarcheshmeh copper complex. Bioleaching experiments were performed by using mixed culture of A. ferrooxidans, A. thiooxidans and L. ferrooxidans from Sarcheshmeh Copper Mine in shaker utensils. Metallurgical dust mostly contained secondary sulphides products such as chalcocite and covellite, and concentrate mostly contained primary sulphides product such as chalcopyrite. The extraction rate of copper was achieved 0.835 g/L/day and 0.403 g/L/day from dust and concentrate, respectively. Also, kinetic studies showed that the rate constants of dust and concentrate were 0.125 day-1 and 0.010 day-1, respectively. The impact of mineralogical characteristics of the material on bioleaching operations was significant. Due to highly solubility rates of secondary sulphides, recovery rate and a higher overall copper recovery was obtained from dust in comparison to concentrate. Chalcopyrite oxidation was stopped at relatively low amounts (about 44%) and additional bioleaching time have not been improve it. The experiments showed that standard mesophilic culture at 35 ° C was very successful in bioleaching of secondary sulfide minerals, but bioleaching of primary copper sulfide minerals especially chalcopyrite by the culture was not effective.