Bioleaching of Metals from Tail-Serpentine by Aspergillus niger

Abstract

There are significant quantities of metallic elements contained in low-grade ores and mining residues. However, some of them potentially endanger the environment, as elements may be released into the environment in hazardous form. Hence, mining industries are seeking an efficient, economic technique to treat these ores. Bio-hydrometallurgical technique is a new method being developed for metal bioleaching, while hydrometallurgical techniques are either expensive, energy intensive or have negative impacts on the environment. In this paper, an attempt was made to prove that Aspergillus niger excreted a great amount of oxalic acid in the first 4 days, which exhibits good potential for metal solubilization. The result shows better bioleaching efficiency by the one-step process employing A. niger. A total of 1% (w/v) tail-serpentine suspension gave the maximum metal extraction yields (in percentage of the amount applied). Finally, maximum solubilization of 68, 20, 50, 16 and 67% were achieved for magnesium, iron, cobalt, nickel and manganese, respectively.