Semiconductor Aspects of Chalcopyrite and its Relevance for Copper Bioleaching: A Review

ABSTRACT

The demand for copper drives hydrometallurgical innovation amidst high-grade resource depletion. Compared to pyrometallurgy, biohydrometallurgy presents eco-friendly, cost-effective solutions for ore processing. Semiconductor minerals, notably chalcopyrite, which corresponds to the largest source of copper in the earth’s crust, play a critical role. However, chalcopyrite electrochemical behavior in bioleaching remains underexplored. Therefore, this review emphasizes the exploration of irradiation’s influence on biohydrometallurgy, particularly through the utilization of photoreactions or mineral photo corrosion. The focus is on examining the semiconductor properties of chalcopyrite to incorporate it into biohydrometallurgical frameworks and to develop models elucidating the impact of light on the bioleaching of chalcopyrite.

KEY FINDINGS

1. Chalcopyrite leaching is governed by semiconductive properties rather than passive layer formation.

2. The transport of charge carriers across the space charge region may be the rate-limiting step in hydrometallurgical processes.

3. High solution potentials lead to charge carrier depletion and reduced reaction kinetics in the dark.

4. Electron injection into Fe3d S3p antibonding orbitals at low solution potentials increases charge carrier concentration, enhancing reduction and intermediate formation.

5. Light irradiation boosts reaction rates by exciting electrons, facilitating their capture by Fe³⁺ ions, aiding bioleaching, and injecting electrons into the photo-generated holes.

Suggestions for future research in the area of biohydrometallurgy:

1. Investigate conditions favoring the accumulation of majority charge carriers on the chalcopyrite surface.

2. Explore light irradiation with sufficient energy to excite electrons from the valence band to the empty orbitals between the valence and conduction bands and the conduction band itself, using different wavelengths.

3. Study the combined effects of light and iron-oxidizing microorganisms on chalcopyrite bioleaching.

4. Therefore, understanding and applying the semiconductor nature of chalcopyrite is crucial for improving hydrometallurgical processes and enhancing copper recovery efficiency through photo-biohydrometallurgy.

KEYWORDS:

• Semiconductor electrochemistry
• photo-bioleaching
• chalcopyrite
• light
• solution potential

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Universidade Estadual Paulista (UNESP) and financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001.