Abstract

The main concern of this study is to find a feasible and economical technique to recover metals from oxide low-grade ore microbially. Owing to the large quantities of metals that are embodied in low-grade ores and mining residues, these are considered new sources of metals. On the other hand they potentially imperil the environment, as the metals they contain may be released to the environment in a hazardous form. Hence, mining industries are seeking an efficient technique to handle these ores. Pyrometallurgical and hydrometallurgical techniques are either very expensive or have a negative impact on the environment. That is why a new environmental strategy called "sustainable development" is coming into perspective. This study employs heterotrophic leaching that falls into this new environmental strategy. In this study, by employing Aspergillus niger , the feasibility of recovery of metals from a mining residue is shown. A. niger exhibits good potential in generating varieties of organic acids effective for metal solubilization. Organic acid effectiveness was enhanced when sulphuric acid was added to the medium. Different agricultural wastes were evaluated and the maximum solubilization of 68%, 46% and 34% was achieved for copper, zinc and nickel, respectively. Also iron codissolution of 7% was gained.