ABSTRACT
Based upon the success of the early operations, bioleaching processes have gradually gained acceptance in the extractive metal industry. Approximately 18-25% of total copper is produced through bacterially assisted heap or dump leaching of low grade copper sulphide ores (Brierley and Brierley 2001, Watling 2006). Similarly, it was estimated in 1993 that 12-13% of total uranium production resulted from the bioleaching processes (Mwaba 1993). Biooxidation of refractory gold concentrates has proven to be a feasible alternative to roasting and pressure oxidation on a commercial scale (Rawlings et al. 2003, Clark et al. 2006). Nonetheless, bioleaching of base metal sulphides has been extensively investigated at laboratory and pilot scales and have proven feasible processes (Steemson et al. 1997, Gericke and Pinches 1999, van Staden 1998, Gilbertson 2000, Clark et al. 2006).
