TY - JOUR
T1 - Study of the dissolution of chalcopyrite in solutions of different ammonium salts
AU - Moyo, T.
AU - Petersen, J.
N1 - Funding Information:
The authors would like to acknowledge the Centre for Bioprocess Engineering Research, the Centre for Imaging and Analysis at the University of Cape Town, and Professor M.J. Nicol for their contribution to this work. This project has been funded through the Minerals to Metals Research Initiative, which is supported by the South African Research Chairs Initiative of the Department of Science and Technology and National Research Foundation (NRF) of South Africa. Any opinion, finding, and conclusion or recommendation expressed in this material is that of the authors and the NRF does not accept any liability in this regard.
Publisher Copyright:
© The Southern African Institute of Mining and Metallurgy, 2016.
PY - 2016/6
Y1 - 2016/6
N2 - The oxidative leaching of chalcopyrite in ammoniacal solutions has been evaluated using electro-analytical techniques and controlled bulk leaching studies. The anodic dissolution process has been established to be a sevenelectron transfer process under nitrogen in ammonia-ammonium sulphate solutions and ammonia-ammonium carbonate solutions, which suggests that the sulphur is oxidized to thiosulphate and the copper and iron released as Cu+ and Fe2+ in these systems. The deportment of Fe2+ and S2O32-is affected by choice of the ammonium salt used in the leaching process. In the perchlorate salt, only five electrons are transferred, supporting formation of different sulphur species as proposed for the sulphate and carbonate salts. Scanning electron microscopy and energydispersive spectroscopic analysis of the mineral surface after leaching indicate presence of an iron-sulphur surface layer completely free of copper in the sulphate system, an iron-rich surface layer in the perchlorate solutions, and absence of surface layer build-up in carbonate solutions. XRD analysis of a bulk leach residue from leaching in ammoniaammonium sulphate solutions showed the surface layer to be mostly amorphous (90%). The crystalline content (10%) is composed of 95% polymorphs of anhydrous iron oxide hydroxide FeO(OH). Choice of ammonium salt and the hydrodynamic environment of leaching have been shown to influence the presence or absence of the surface product, as well as its nature.
AB - The oxidative leaching of chalcopyrite in ammoniacal solutions has been evaluated using electro-analytical techniques and controlled bulk leaching studies. The anodic dissolution process has been established to be a sevenelectron transfer process under nitrogen in ammonia-ammonium sulphate solutions and ammonia-ammonium carbonate solutions, which suggests that the sulphur is oxidized to thiosulphate and the copper and iron released as Cu+ and Fe2+ in these systems. The deportment of Fe2+ and S2O32-is affected by choice of the ammonium salt used in the leaching process. In the perchlorate salt, only five electrons are transferred, supporting formation of different sulphur species as proposed for the sulphate and carbonate salts. Scanning electron microscopy and energydispersive spectroscopic analysis of the mineral surface after leaching indicate presence of an iron-sulphur surface layer completely free of copper in the sulphate system, an iron-rich surface layer in the perchlorate solutions, and absence of surface layer build-up in carbonate solutions. XRD analysis of a bulk leach residue from leaching in ammoniaammonium sulphate solutions showed the surface layer to be mostly amorphous (90%). The crystalline content (10%) is composed of 95% polymorphs of anhydrous iron oxide hydroxide FeO(OH). Choice of ammonium salt and the hydrodynamic environment of leaching have been shown to influence the presence or absence of the surface product, as well as its nature.
UR - http://www.scopus.com/inward/record.url?scp=84982814993&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84982814993&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:84982814993
SN - 2225-6253
VL - 116
SP - 509
EP - 516
JO - Journal of the Southern African Institute of Mining and Metallurgy
JF - Journal of the Southern African Institute of Mining and Metallurgy
IS - 6
ER -