Journal of Sustainable Metallurgy

, Volume 4, Issue 1, pp 77–94 | Cite as

The Submerged Arc Furnace (SAF): State-of-the-Art Metal Recovery from Nonferrous Slags

  • Bernd Friedrich
  • Michael Kalisch
  • David FriedmannEmail author
  • Rolf Degel
  • Frank Kaußen
  • Jörn Böhlke
Thematic Section: Slag Valorisation
Part of the following topical collections:
  1. Slag Valorisation


The submerged electric arc furnace (SAF) has proven a versatile unit in numerous metallurgical applications for more than a century. Countless innovations have made this furnace type become the most commonly used furnace for increased metal recoveries and slag-cleaning operations. In many applications, SAFs are also employed as primary melting units (e.g., Ni Laterites, Si production, FeMn, FeCr, etc.). Furnace power supply as well as capacities has been continuously increased over the years so that modern SAFs can reach more than 100 MVA as well as more than 100 tph in throughput. The present paper aims to provide a thorough overview of the principles and buildup of modern SAFs and to present various examples from recent industrial installations as well as current topics in pyrometallurgical research. Examples of the buildup and special equipment (such as cooled wall panels, Soderberg electrodes, etc.) of modern SAFs are demonstrated. The paper also presents metallurgical, thermochemical, and physical fundamentals of slag cleaning as well as particle settling. Furthermore, industrial examples from two African sites are discussed, which highlight the advantages of the SAF for metal recoveries. Special emphasis is given to an innovative slag-cleaning concept through magnetic agitation. Research topics presented range from the inertization of red mud, to Co recovery through the retreatment of dumped slag and the valorization of Pb- and Zn-containing slags.


SAF Submerged-arc-furnace Slag-cleaning Slag-washing-machine Cobalt-recovery Redmud 


Compliance with Ethical Standards

Conflict of interest

The authors declare that they have no conflict of interest.


  1. 1.
    Kempken J, Degel R (2005) A hot technology. Met Bull Mon, pp 23–26Google Scholar
  2. 2.
    Degel R, Kunze J, Oterdoom H, Wübbels T, Kempken J (2007) Rectangular furnace design, furnace modelling and- slag washing machine for the non-ferrous industry. In: European Metallurgical Conference (EMC) Proceedings 2007, GDMB, Düsseldorf, Germany. ISBN 978-3-940276-08-7Google Scholar
  3. 3.
    Degel R, Kunze J (2003) History, current status of submerged arc furnace technology for ferro alloy metals. Steel Grips 1(3).
  4. 4.
    Kempken J, Degel R (2006) 100 years of SMS demag submerged arc furnace technology. In: World of metallurgy—ERZMETALL, vol 59, no 3, pp 143–151. ISSN 1613-2394Google Scholar
  5. 5.
    Warczok A (2003) SAF fundamentals, stage I. Universidad de Chile, SantiagoGoogle Scholar
  6. 6.
    Oeters F (1989) Metallurgie der Stahlherstellung [Metallurgy of steel making]. Springer, Berlin, p 880. ISBN 3-540-51040-0CrossRefGoogle Scholar
  7. 7.
    Volkert G, Frank KD (1972) Metallurgie der Ferrolegierungen [Metallurgy of ferro alloys]. Springer, Berlin. ISBN 978-3540052029Google Scholar
  8. 8.
    Degel R, Kunze J, Oterdoom H, Warczok A, Riveros G (2009) Computer simulator of slag cleaning in an electric furnace. In: Proceedings of Copper 2007. The Carlos Diaz Symposium on Pyrometallurgy, Toronto, Canada, pp 367–378. ISBN 978-1-894475-73-0Google Scholar
  9. 9.
    Grigoryan V, Belyanchikov L, Stomakhin A (1989) Theoretical principles of electric steelmaking. Mir Publishers, MoscowGoogle Scholar
  10. 10.
    Degel R, Kunze J, Kalisch M, Oterdoom H, Warczok A, Riveros G (2009) Latest results of the intensive slag cleaning reactor for metal recovery on the basis of copper. In: Proceedings of Copper 2010, GDMB, Hamburg, Germany, pp 1213–1232. ISBN 978-3-940276-32-2Google Scholar
  11. 11.
    Kunze J, Degel R, Borgwardt D, Warczok A, Riveros G. Method and device for extracting a metal from slag containing the metal. Patent: WO/2006/131372Google Scholar
  12. 12.
    Zander M, Friedrich B, Schmidl J, Hoppe M, Degel R, König R (2013) Efficiency of slag cleaning in a magnetically induced stirring reactor. In: European Metallurgical Conference (EMC) Proceedings 2013, GDMB, Weimar, Germany. ISBN 978-3-940276-52-0Google Scholar
  13. 13.
    König R, Weyer A, Degel R, Schmidl J, Kadereit H, Specht A (2013) Highly efficient slag cleaning—latest results from pilot-scale tests. In: Kvithyld A et al (eds) REWAS 2013. Springer, Cham. CrossRefGoogle Scholar
  14. 14.
    Kaußen F, Friedrich B (2015) Reductive smelting of red mud for iron recovery, Chemie Ingenieur Technik (CIT, ISSN: 1522-2640), vol 87, no 11. Wiley, New York. CrossRefGoogle Scholar
  15. 15.
    Singh HP. Implementation of a novel technology for the recovery of cobalt from copper smelter slags (at Chambishi Metals Plc, Zambia). Dissertation 2012, RWTH Aachen University, p 909. ISBN: 978-3-8440-0960-6Google Scholar
  16. 16.
    Böhlke J. Behandlung von Schlacken der Bleigewinnung im Elektrolichtbogenofen [Treatment of slags from Pb production in an electric arc furnace]. Dissertation 2016, RWTH Aachen University, p 913. ISBN: 978-3-8440-4763-9Google Scholar
  17. 17.
    Gubernan DE (2012) Minerals yearbook: lead (advance release). U.S. Department of the Interior, U.S. Geological Survey. ISBN 978-1-4113-3349-9Google Scholar
  18. 18.
    Hayes PC, Schlesinger ME, Steil H-U, Siegmund A (2010) Lead smelter survey. In: PbZn 2010: Proceedings of Lead-Zinc 2010, Vancouver, Canada. Wiley, New York. ISBN 978-0-470-94315-1Google Scholar
  19. 19.
    Kempken J, Degel R, Schreiter T, Schmieden H (2006) History and innovation of SMS Demag smelting technologies. In: Proceedings of the 2nd International Platinum Conference “Platinum Surges Ahead”, SAIMM, Sun City, South AfricaGoogle Scholar
  20. 20.
    Warczok A (2003) SAF fundamentals, mathematical model of copper slag cleaning. Universidad de Chile, SantiagoGoogle Scholar

Copyright information

© The Minerals, Metals & Materials Society 2018

Authors and Affiliations

  • Bernd Friedrich
    • 1
  • Michael Kalisch
    • 2
  • David Friedmann
    • 1
    Email author
  • Rolf Degel
    • 2
  • Frank Kaußen
    • 1
  • Jörn Böhlke
    • 1
  1. 1.IME Process Metallurgy and Metal Recycling, RWTH Aachen UniversityAachenGermany
  2. 2.SMS Group GmbHDüsseldorfGermany

Personalised recommendations