Influence of CO2 supplementation on bioleaching kinetics in stirred tank reactor (STR).

The demand for CO2 was investigated during bioleaching of sulphidic materials in a stirred tank reactor using a bacterial consortium which included Leptospirillum ferriphilum, Acidithiobacillus caldus and Sulphobacillus. Batch tests were carried out in 2 litre reactors at 10% w/w solid load using a copper concentrate from flotation of a black shale organic-rich ore in which the carbonates dissolve in acidic conditions to produce CO2. The results showed that Fe oxidation (and thus microbial activity) was delayed when air was injected without CO2-supplementation, and that CO2-supplementation improved leaching kinetics. A methodology to determine gas/liquid transfer components and to asses CO2 limitations in the system showed that the microorganisms were not only sensitive to the transfer rate of CO2 from the gas to the liquid phase, but also to the availability of CO2 in solution.
The demand for CO2 was investigated during bioleaching of sulphidic materials in a stirred tank reactor using a bacterial consortium which included Leptospirillum ferriphilum, Acidithiobacillus caldus and Sulphobacillus. Batch tests were carried out in 2 litre reactors at 10% w/w solid load using a copper concentrate from flotation of a black shale organic-rich ore in which the carbonates dissolve in acidic conditions to produce CO2. The results showed that Fe oxidation (and thus microbial activity) was delayed when air was injected without CO2-supplementation, and that CO2-supplementation improved leaching kinetics. A methodology to determine gas/liquid transfer components and to asses CO2 limitations in the system showed that the microorganisms were not only sensitive to the transfer rate of CO2 from the gas to the liquid phase, but also to the availability of CO2 in solution.