Sulfur enhancement effects for uranium bioleaching in column reactors from a refractory uranium ore

Area of Science:

• Biotechnology
• Metallurgy
• Environmental Science

Background:

• Refractory uranium ores pose challenges for traditional bioleaching.
• Optimizing microbial consortia and process conditions is crucial for efficient uranium recovery.

Purpose of the Study:

• To assess the feasibility of sulfur enhancement for uranium bioleaching.
• To investigate the impact of sulfur on microbial community dynamics and ore characteristics.
• To elucidate the mechanism of sulfur-enhanced uranium bioleaching.

Main Methods:

• Column reactor bioleaching experiments using a mixed culture of *Acidithiobacillus ferrooxidans*, *Acidithiobacillus thiooxidans*, and *Leptospirillum ferriphilum*.
• Comparative analysis of uranium extraction with and without sulfur addition.
• Kinetic modeling, ore residue characterization, and bacterial community analysis.

Main Results:

• Uranium extraction reached 86.2% with 1 g/kg sulfur enhancement over 77 days, a 12.6% increase compared to the control.
• Kinetic analysis indicated an internal diffusion through the product layer-controlled model.
• Sulfur enhancement improved ore permeability by strengthening the porosity of the passivation layer.
• A balanced ratio (approx. 1:1) of iron-oxidizing and sulfur-oxidizing bacteria was observed, enhancing ore decomposition.

Conclusions:

• Sulfur enhancement is a feasible and effective strategy for improving uranium bioleaching from refractory ores.
• The mechanism involves enhanced ore permeability and a balanced microbial community structure.
• This approach offers a promising method for increasing uranium recovery efficiency.