Hadi Abdollahi - School of Mining, College of Engineering, University of Tehran, Tehran ۱۴۳۹۹۵۷۱۳۱, Iran
Seyed Ziaedin Shafaei - School of Mining, College of Engineering, University of Tehran, Tehran ۱۴۳۹۹۵۷۱۳۱, Iran
Mohammad Noaparast - School of Mining, College of Engineering, University of Tehran, Tehran ۱۴۳۹۹۵۷۱۳۱, Iran
Z Manafi - School of Mining, College of Engineering, University of Tehran, Tehran ۱۴۳۹۹۵۷۱۳۱, Iran- Department of Mining Engineering, Mineral Processing Division (Mineral-Metal Recovery and Recycling Research Group), Suleyman Demirel University, Isparta TR۳۲۲۶۰, Tur

Bioleaching processes for extraction of Cu and Mo from molybdenite cons. are more environmentally friendly and consume less energy than conventional technologies, yet less economically efficient. One necessary step towards arriving at a cost-effective bioleaching process is using appropriate methodology to optimize pertinent factors in such processes. To this end, the present study employed Response Surface Methodology to optimize important factors in a molybdenite bioleaching process by mix mesophilic microorganism using shake flasks. The effect of change in the levels of molybdenite concentration, pyrite and silver ion concentration as additives - in the range 3-9%, 1-5%, and 0-1.2gr/l, respectively - on the rate of Cu and Mo bioleaching was studied using a Central Composite Design. The results showed a statistically significant effect of silver ion and molybdenite concentration, and to a lesser pyrite concentration, on the rate of bioleaching of Cu and Mo. Further, different mediums and additives were evaluated for copper and molybdenum extraction from molybdenite concentrate in bioleaching process. Small amounts of silver (100mgr/l AgSO4) dramatically accelerated the copper dissolution process. Addition of FeS2 and sulfur with ferrous sulfate accelerated the acidification and raised the oxidation-reduction potential of solution (medium) with an inoculation of 15% (v/v) of active and adapted indigenous mesophilic bacteria, thus resulting in an overall increase in Mo dissolution efficiency.

additive, biohydrometallurgy, Cu and Mo dissolution, mixed mesophilic bacteria, modeling and optimization, molybdenite concentrate