<p>Chalcopyrite bioleaching often faces challenges such as prolonged processing times, low recoveries, large operational footprints, and difficulties in maintaining consistent microbial activity, particularly when dealing with low-grade ores. This study employs a bio-hydrometallurgical method using bio-acid derived from the bioleaching of pyrite ore, which transforms coal tailings wastes from Central Appalachian and Illinois Basins that would otherwise need to be treated to mitigate acid mine drainage into a valuable leaching agent. The research investigates the dissolution behavior and leaching kinetics of high-grade chalcopyrite in spent medium bio-acid, examining the synergistic effects of solution pH and oxidation–reduction potential on copper extraction, with an optimal leaching efficiency of 59.88% achieved in 48 h at 75 ℃. Factors such as temperature and stirring speed also significantly influence leaching efficiency. Advanced material characterization techniques, including Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM–EDS) and X-ray Diffraction (XRD), revealed the mineral surface transformations and the formation of insoluble species such as elemental sulfur and jarosite, which may impact leaching kinetics and efficiency. The application of X-ray Photoelectron Spectroscopy showed the presence of intermediate products (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$CuS\,and\,Cu_{2} S$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>C</mi> <mi>u</mi> <mi>S</mi> <mspace width="0.166667em" /> <mi>a</mi> <mi>n</mi> <mi>d</mi> <mspace width="0.166667em" /> <mi>C</mi> <msub> <mi>u</mi> <mn>2</mn> </msub> <mi>S</mi> </mrow> </math></EquationSource> </InlineEquation>) that are formed during chalcopyrite dissolution. The leaching activation energy was determined to be 39.01 kJ/mol between 25 ℃ to 75 ℃, indicating an intra-diffusion control mechanism. These findings indicate the potential of using waste-derived bio-acid for copper extraction, presenting a sustainable and efficient alternative to conventional methods. Mechanistic insights on the synergistic effect of pH and solution potential on chalcopyrite dissolution were elucidated, and recommendations for optimizing leaching conditions and scaling up for industrial applications were discussed.</p> Graphical Abstract <p></p>

Chalcopyrite Leaching in Waste-Derived Bio-Acid: Part I – Mechanistic Insights and Leaching Kinetics

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发表日期：

2025年12月10日

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Emmanuel Yaw Owusu-Fordjour,
Xinbo Yang,
Wei Liu,
Jacob P. Burke,
Michael L. Free

摘要

Chalcopyrite bioleaching often faces challenges such as prolonged processing times, low recoveries, large operational footprints, and difficulties in maintaining consistent microbial activity, particularly when dealing with low-grade ores. This study employs a bio-hydrometallurgical method using bio-acid derived from the bioleaching of pyrite ore, which transforms coal tailings wastes from Central Appalachian and Illinois Basins that would otherwise need to be treated to mitigate acid mine drainage into a valuable leaching agent. The research investigates the dissolution behavior and leaching kinetics of high-grade chalcopyrite in spent medium bio-acid, examining the synergistic effects of solution pH and oxidation–reduction potential on copper extraction, with an optimal leaching efficiency of 59.88% achieved in 48 h at 75 ℃. Factors such as temperature and stirring speed also significantly influence leaching efficiency. Advanced material characterization techniques, including Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM–EDS) and X-ray Diffraction (XRD), revealed the mineral surface transformations and the formation of insoluble species such as elemental sulfur and jarosite, which may impact leaching kinetics and efficiency. The application of X-ray Photoelectron Spectroscopy showed the presence of intermediate products ( $CuS\,and\,Cu_{2} S$ $C u S a n d C u_{2} S$ ) that are formed during chalcopyrite dissolution. The leaching activation energy was determined to be 39.01 kJ/mol between 25 ℃ to 75 ℃, indicating an intra-diffusion control mechanism. These findings indicate the potential of using waste-derived bio-acid for copper extraction, presenting a sustainable and efficient alternative to conventional methods. Mechanistic insights on the synergistic effect of pH and solution potential on chalcopyrite dissolution were elucidated, and recommendations for optimizing leaching conditions and scaling up for industrial applications were discussed.

Graphical Abstract