Mohammad Zaki Mubarok

Bioleaching of Supergene Porphyry Copper Ores from Sungai Mak Gorontalo of Indonesia by an Iron- and Sulfur-Oxidizing Mixotrophic Bacterium

Environmentally friendly mining technologies have to be developed extensively to avoid the impact of mining activities with respect to environmental concern. One example of such technology is bioleaching which has been developed worldwide and is regarded as an appropriate technology for the extraction of metals from polymetallic ores such as supergene porphyry copper ores, mainly consisting of secondary copper sulfides, including chalcocite (Cu2S), covellite (CuS), or oxide minerals, i.e., cuprite (Cu2O) and tenorite (CuO). The extraction process for this complex ore generally requires high temperature, high pressure and/or high acid concentration. For the economic extraction of valuable copper from such ores, the bioleaching of supergene porphyry copper ore from Sungai Max in Southeast Sulawesi of Indonesia was investigated in shake-flask experiments at room temperature (28 °C) for 14 days using an iron- and sulfur-oxidizing bacterium (Alicyclobacillus sp.) indigenous to an Indonesian mine site. The main mineralogical composition of gangue minerals contained in this ore sample included quartz, muscovite, kaolinite and alunite. The relatively high copper extraction efficiencies were obtained over a 14-day period of the bioleaching experiments as a function of pH, pulp density and NaCl concentration. Therefore, the findings of this study provide the first information of bioleaching process of supergene porphyry copper ores in Indonesia that may highly be useful for developing an economical and environmentally friendly extraction process of such complex ores.

Isolation and phylogenetic characterization of iron-sulfur-oxidizing heterotrophic bacteria indigenous to nickel laterite ores of Sulawesi, Indonesia: Implications for biohydrometallurgy

The main objective of this study was to isolate and phylogenetically identify the indigenous iron-sulfur-oxidizing heterotrophic bacteria capable of bioleaching nickel from laterite mineral ores. The bacteria were isolated from a nickel laterite mine area in South Sulawesi Province, Indonesia. Seven bacterial strains were successfully isolated from laterite mineral ores (strains SKC/S-1 to SKC/S-7) and they were capable of bioleaching of nickel from saprolite and limonite ores. Using EzTaxon-e database, the 16S rRNA gene sequences of the seven bacterial strains were subjected to phylogenetic analysis, resulting in a complete hierarchical classification system, and they were identified as Pseudomonas taiwanensis BCRC 17751 (98.59% similarity), Bacillus subtilis subsp. inaquosorum BGSC 3A28 (99.14% and 99.32% similarities), Paenibacillus pasadenensis SAFN-007 (98.95% and 99.33% similarities), Bacillus methylotrophicus CBMB 205 (99.37% similarity), and Bacillus altitudinis 41KF2b (99.37% similarity). It is n...