Investigation of the reduction roasting of saprolite ores in the Caron Process: microstructure and thermodynamic analysis

ABSTRACT

Studies have been undertaken to investigate the thermodynamic aspects of the reduction roasting of saprolite ores in the Caron Process. Reduction experiments have been conducted in controlled oxygen partial pressure conditions at selected temperatures. Detailed microstructure characterisation and thermodynamic analysis of reduced ore samples, focusing on the phase transformations, nickel recoveries and Ni-Fe alloy compositions produced, were carried out. Comparison has been made between the experimental results and FactSage thermodynamic predictions for these conditions. The differences between between the experimental and predicted results are discussed. It has been shown that the system below 700°C is approximated thermodynamically by considering the nickel–iron alloy product to be in chemical equilibrium with a metastable amorphous oxide phase.

KEYWORDS:

• Saprolite
• thermodynamics
• reduction roasting
• ferronickel alloy
• microstructure
• leaching
• recovery

Acknowledgements

The authors would like to acknowledge financial support for this research from the Australian Research Council Linkage program (Project No LP0562201) and our industry sponsor, QNI Yabulu, Townsville, Queensland, Australia. Particular thanks are due to John Fittock, QNI for his invaluable assistance in obtaining mineral samples for the research, and for providing valuable insight into the principles and industrial operation of the Caron process used at QNI. Thanks also to the staff of The University of Queensland’s Centre for Microanalysis and Microscopy (CMM) for their support for sample analysis undertaken in the Centre.

Disclosure statement

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

Additional information

Funding

The authors would like to acknowledge financial support for this research from the Australian Research Council Linkage program (Project No LP0562201) and our industry sponsor, QNI Yabulu, Townsville, Queensland, Australia. Particular thanks are due to John Fittock, QNI for his invaluable assistance in obtaining mineral samples for the research, and for providing valuable insight into the principles and industrial operation of the Caron process used at QNI. Thanks also to the staff of The University of Queensland’s Centre for Microanalysis and Microscopy (CMM) for their support for sample analysis undertaken in the Centre.

Notes on contributors

J. Chen

Dr J. Chen in School of Chemical Engineering, The university of Queensland, Brisbane, Australia.

E. Jak

Prof E. Jak in School of Chemical Engineering, The university of Queensland, Brisbane, Australia.

P. C. Hayes

Professor P. C. Hayes in Formerly School of Chemical Engineering, The University of Queensland, Brisbane, Australia.