Non-homogeneous biofilm modeling applied to bioleaching processes

Area of Science:

• Biogeochemistry
• Computational Modeling
• Microbial Ecology

Background:

• Bioleaching is crucial for metal recovery from ores.
• Understanding biofilm dynamics is key to optimizing bioleaching processes.
• Mineral passivation limits the efficiency of metal solubilization.

Purpose of the Study:

• To develop a novel 2D non-homogeneous biofilm model for studying microorganism-scale reactions in bioleaching.
• To investigate the spatial and temporal relationships between chemical reactions, microorganism growth, and biofilm morphology.
• To analyze the impact of inorganic precipitate formation on diffusion limitations and mineral solubilization.

Main Methods:

• A particle-based modeling strategy was employed to represent discrete phases and contact reactions.
• Simulations incorporated diffusion limitations caused by inorganic particle accumulation.
• The model studied chemical chalcopyrite leaching and the behavior of iron and sulfur-oxidizing microorganisms.

Main Results:

• Chalcopyrite passivation occurs due to impervious solid layer formation, hindering diffusion.
• Chemolithoautotrophic biofilms delay passivation by forming corrosion pits and increasing porosity via sulfur dissolution.
• Low iron concentrations favor flat biofilm morphology, enhancing sulfur dissolution over iron oxidation.

Conclusions:

• The developed biofilm model accurately represents heterogeneous systems with abiotic particles.
• Biofilm strategies can effectively mitigate passivation, improving bioleaching efficiency.
• Understanding biofilm morphology and microbial activity is critical for optimizing mineral processing.