Ferrous iron oxidation and uranium extraction by Thiobacillus ferrooxidans

Area of Science:

• Biotechnology
• Environmental Science
• Hydrometallurgy

Background:

• Uranium extraction from low-grade ores presents economic and environmental challenges.
• Microbial leaching offers a potential solution for efficient metal recovery.
• Thiobacillus ferrooxidans is a key microorganism in bioleaching processes.

Purpose of the Study:

• To investigate the microbiological oxidation of ferrous iron by Thiobacillus ferrooxidans for uranium extraction.
• To determine the influence of agitation and aeration on oxidation kinetics.
• To evaluate uranium solubilization efficiency from low-grade ore.

Main Methods:

• Batch and continuous culture systems were employed.
• Parameters like agitation and aeration were controlled to optimize oxygen transfer.
• Kinetic analysis using an adapted Monod equation (Vmax, K) was performed.
• Power requirements for leaching were calculated.

Main Results:

• Agitation and aeration significantly influenced oxygen saturation, mass transfer, and ferrous iron oxidation rates.
• Kinetic parameters (Vmax, K) were determined for Thiobacillus ferrooxidans.
• Initial leaching achieved 68% uranium extraction within nine days.
• Regrinding and secondary leaching increased uranium solubilization to 87%.

Conclusions:

• Thiobacillus ferrooxidans effectively facilitates uranium extraction through ferrous iron oxidation.
• Process parameters like agitation and aeration are critical for optimizing bioleaching efficiency.
• A two-stage leaching process, including regrinding, significantly enhances overall uranium recovery from low-grade ores.