Kinetic and Thermodynamic Analysis of the Reduction of Oxides of Cu and Co in a SiO2-CaO-(Al,Fe)2O3 Slag

  • Yotamu Stephen Rainford Hara
  • Animesh Jha
Conference paper


The investigation focuses on a low temperature recovery of Cu and Co from a 40 wt% SiO2-(30 wt%Fe,6 wt%Al)2O3-10wt% CaO-7wt%CuO-7wt%CoO slag over a temperature range of 1173K to 1323K. The alloy phases containing Cu-Co and Fe-Co alloy formed via the carbothermic reduction of oxides: MO + C = M + CO(g), where M represents metallic copper, cobalt or iron. In the direct reduction of oxides, the recovery of metallic phase was well below 90% at 1323K, due to the kinetic barrier which was analysed and attributed to oxygen and metal-ion transport in the slag. This barrier was overcome by adding CaSO4 and carbon, which yields a matte (MS) phase via MO + CaSO4 + 4C = MS + CaO + 4CO reaction. Lime thus produced in situ participates in metal oxide/metal sulphide reduction reactions, which are analysed with the help of X-ray powder diffraction, scanning electron microscopy, and thermogravimetric analysis.

Key words

Cu-Co slag Carbothermic reduction Kinetics Thermodynamics Sulphidation 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Davenport, W.G.L., et al., Extractive Metallurgy of Copper (4th Edition). Chemical, Petrochemical & Process, (2002), Elsevier, 1–452.CrossRefGoogle Scholar
  2. 2.
    Imris, I., Cobalt distribution in Rokana smelter. Transactions of the Institution of Mining and Metallurgy, Section C: Mineral Processing and Extractive Metallurgy, (1982), 91, p. C153-C161.Google Scholar
  3. 3.
    Jones, R.T., et al., Recovery of cobalt from slag in a DC arc furnace at Chambishi, Zambia. Journal of The South African Institute of Mining and Metallurgy, (2002). 102(Compendex), 5–9.Google Scholar
  4. 4.
    Bale, C.W., et al., Fact Sage thermochemical software and databases. Calphad: Computer Coupling of Phase Diagrams and Thermochemistry, (2002). 26(2), 189–228.CrossRefGoogle Scholar
  5. 5.
    Turkdogan, E.T., Physical chemistry of high temperature technology, (Academic Press, 1980).Google Scholar
  6. 6.
    Turkdogan, E.T., et al., Rate of oxidation of graphite in carbon dioxide. Carbon, (1968), 6(4), 467–484.CrossRefGoogle Scholar
  7. 7.
    Cutler, C.J., et al. Phasing out reverbatory furnace operations at KCM Nkana. in Southern African Pyrometallurgy 2006. 2006. Johannesburg, South Africa.Google Scholar
  8. 8.
    Stephen, Y., R. Hara, and A. Jha, A Novel Low-Energy Route for the Extraction of Copper and Cobalt Metals/Alloys from the Zambian Sulphide Concentrates. Characterization of Minerals, Metals, and Materials, (2012), 77–87.Google Scholar
  9. 9.
    Hara, Y. and A. Jha, Carbothermic reduction of Zambian sulphide concentrates in presence of lime, Mineral Processing and Extractive Metallurgy, (2013), 122(3), 146–156.CrossRefGoogle Scholar
  10. 10.
    Manasse, A. and M. Mellini, Chemical and textural characterisation of medieval slags from the Massa Marirtima smelting sites (Tuscany, Italy), Journal of Cultural Heritage, (2002). 3(3), 187–198.CrossRefGoogle Scholar
  11. 11.
    Ward, C.R. and D. French, Determination of glass content and estimation of glass composition in fly ash using quantitative X-ray diffractometry, Fuel, (2006), 85(16), 2268–2277.CrossRefGoogle Scholar
  12. 12.
    W.D, K., B. H.K, and U. D.R., Introduction to ceramics (2nd Ed., 1976, New York, Chichester, John Wiley).Google Scholar
  13. 13.
    Habashi, F., Kinetics of metallurgical processes, (Metallurgie Extractive, Quebec, Canada, 1999).Google Scholar
  14. 14.
    Rao, Y.K. and B.P. Jalan, A study of the rates of carbon-carbon dioxide reaction in the temperature range 839 to 1050 C, Metallurgical Transactions, (1972), 3(9), 2465–2477.CrossRefGoogle Scholar
  15. 15.
    Matsui, I., D. Kunii, and T. Furusawa, Study of char gasification by carbon dioxide. 1. Kinetic study by thermogravimetric analysis. Industrial & Engineering Chemistry Research, (1987), 26(1), p. 91–95.CrossRefGoogle Scholar
  16. 16.
    Karata and C, Catalysis of the graphite-CO2 reaction by iron from in-situ reduction wustite over the range 870–1100°C, Mineral Processing and Extractive Metallurgy, (2001), 110(1), 7–13.CrossRefGoogle Scholar
  17. 17.
    Karatas, C., Catalytic enhancement of graphite — CO2 reaction by in situ reduced chromium and nickel from their oxides Cr2O3 and NiO over the temperature range 850–1100°C, Mineral Processing and Extractive Metallurgy, (2004), 113(1), 19–24.CrossRefGoogle Scholar
  18. 18.
    Kutsovskaya, M.L., M.T. Hepworth, and J.R. McGaa, Recovery of Lime, Sulfur, and Iron from Gypsum and Pyrite Wastes. Ind. Eng. Chem. Res., (1996), 35(5), 1736–1746.CrossRefGoogle Scholar

Copyright information

© TMS (The Minerals, Metals & Materials Society) 2014

Authors and Affiliations

  • Yotamu Stephen Rainford Hara
    • 1
  • Animesh Jha
    • 1
  1. 1.The Institute for Materials Research, Houldsworth BuildingLeeds UniversityLeedsUK

Personalised recommendations