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The Effect of Different Additives and Medium on the Bioleaching of Molybdenite for Cu and Mo Extraction Using Mix Mesophilic Microorganism

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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.
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... Recently, several bioleaching experiments have been carried out to evaluate the extraction of copper, molybdenum and rhenium from molybdenite concentrate. The results have indicated the successful removal of copper from Mo-concentrate within a short period of bioleaching using mesophilic and thermophilic (moderate and extreme) microorganisms; however, difficulties with low dissolution kinetics were observed for molybdenum and rhenium (Abdollahi et al., 2013a(Abdollahi et al., , 2013b(Abdollahi et al., , 2014(Abdollahi et al., , 2015. These experiments are essential in terms of expanding our knowledge and understanding such complex systems. ...
... Rhenium bearing minerals were neither detected by optical mineralogy nor instrumental techniques (XRD and SEM). Studies have shown that rhenium as elemental form is located within the molybdenite crystalline lattice (Abdollahi et al., 2013a(Abdollahi et al., , 2013b(Abdollahi et al., , 2014(Abdollahi et al., , 2015. ...
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