1632 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
chalcopyrite is a yellow-brassy colour, which is inconsistent
with the simple interpretation based on its small band gap.
This implies a more complex structure that preferentially
absorbs light in the blue region. The upper valence band of
chalcopyrite is antibonding in character, which means the
removing an electron from it does not necessarily result in
bond breaking. However, injecting an electron in this band
might assist in bond breaking, which explains the ferrous-
promoted mechanism and the redox-potential window
sometimes seen. However, to dissolve chalcopyrite at high
rates, a high potential is required to extract electrons from
deeper bonding orbitals.
ACKNOWLEDGMENTS
The author would like to thank Dr Leslie Bryson for many
hours of discussion on this topic.
REFERENCES
Biegler, T. and Horne, M.D., 1985. The Electrochemistry
of Surface Oxidation of Chalcopyrite. J. Electrochem.
Soc., 132, 1363–1369.
Bryson, L.J., Crundwell, F.K. 2014. The anodic dissolu-
tion of pyrite (FeS2) in hydrochloric acid solutions.
Hydrometallurgy, 143, pp. 42–53.
Bryson, L.J., van Aswegen, A., Knights, B. and Crundwell,
F.K., 2016. Investigation of the Mechanism of
Dissolution of Chalcopyrite using Photo-Effects,
Hydrometallurgy Conference 2016: Sustainable
Hydrometallurgical Extraction of Metals. Southern
African Institute of Mining and Metallurgy, Cape
Town.
Crundwell, F.K., 1988a. Effect of iron impurity in zinc
sulfide concentrates on the rate of dissolution. AIChE
Journal, 34 (7), pp. 1128–1134.
Crundwell, F.K., 1988b. The influence of the elec-
tronic structure of solids on the anodic dissolution
and leaching of semiconducting sulphide minerals.
Hydrometallurgy, 21 (2), pp. 155–190.
Crundwell, F.K., 2013. The dissolution and leaching of
minerals: Mechanisms, myths and misunderstandings.
Hydrometallurgy, 139, pp. 132–148.
Crundwell, F.K., 2015. The semiconductor mechanism
of dissolution and the pseudo-passivation of chal-
copyrite. Canadian Metallurgical Quarterly, 54 (3),
pp. 279–288.
Crundwell, F.K., Van Aswegen, A., Bryson, L.J., Biley, C.,
Craig, D., Marsicano, V.D., Keartland, J.M., 2015.
The effect of visible light on the dissolution of natu-
ral chalcopyrite (CuFeS2) in sulphuric acid solutions.
Hydrometallurgy, 158, pp. 119–131.
Figure 7. Band structure of chalcopyrite, shown the absorption peak of visible light, and the upper valence band which has
anti-bonding/non-bonding character
chalcopyrite is a yellow-brassy colour, which is inconsistent
with the simple interpretation based on its small band gap.
This implies a more complex structure that preferentially
absorbs light in the blue region. The upper valence band of
chalcopyrite is antibonding in character, which means the
removing an electron from it does not necessarily result in
bond breaking. However, injecting an electron in this band
might assist in bond breaking, which explains the ferrous-
promoted mechanism and the redox-potential window
sometimes seen. However, to dissolve chalcopyrite at high
rates, a high potential is required to extract electrons from
deeper bonding orbitals.
ACKNOWLEDGMENTS
The author would like to thank Dr Leslie Bryson for many
hours of discussion on this topic.
REFERENCES
Biegler, T. and Horne, M.D., 1985. The Electrochemistry
of Surface Oxidation of Chalcopyrite. J. Electrochem.
Soc., 132, 1363–1369.
Bryson, L.J., Crundwell, F.K. 2014. The anodic dissolu-
tion of pyrite (FeS2) in hydrochloric acid solutions.
Hydrometallurgy, 143, pp. 42–53.
Bryson, L.J., van Aswegen, A., Knights, B. and Crundwell,
F.K., 2016. Investigation of the Mechanism of
Dissolution of Chalcopyrite using Photo-Effects,
Hydrometallurgy Conference 2016: Sustainable
Hydrometallurgical Extraction of Metals. Southern
African Institute of Mining and Metallurgy, Cape
Town.
Crundwell, F.K., 1988a. Effect of iron impurity in zinc
sulfide concentrates on the rate of dissolution. AIChE
Journal, 34 (7), pp. 1128–1134.
Crundwell, F.K., 1988b. The influence of the elec-
tronic structure of solids on the anodic dissolution
and leaching of semiconducting sulphide minerals.
Hydrometallurgy, 21 (2), pp. 155–190.
Crundwell, F.K., 2013. The dissolution and leaching of
minerals: Mechanisms, myths and misunderstandings.
Hydrometallurgy, 139, pp. 132–148.
Crundwell, F.K., 2015. The semiconductor mechanism
of dissolution and the pseudo-passivation of chal-
copyrite. Canadian Metallurgical Quarterly, 54 (3),
pp. 279–288.
Crundwell, F.K., Van Aswegen, A., Bryson, L.J., Biley, C.,
Craig, D., Marsicano, V.D., Keartland, J.M., 2015.
The effect of visible light on the dissolution of natu-
ral chalcopyrite (CuFeS2) in sulphuric acid solutions.
Hydrometallurgy, 158, pp. 119–131.
Figure 7. Band structure of chalcopyrite, shown the absorption peak of visible light, and the upper valence band which has
anti-bonding/non-bonding character