Isabel J. Geldenhuys

Manager, Pyrometallurgy Division, Mintek

Isabel Geldenhuys Ms Isabel Geldenhuys is the Manager of Mintek´s Pyrometallurgy Division. Isabel is a chemical engineer and a registered professional engineer with more than 20 years of pyrometallurgical experience. She has extensive experience in managing research and development projects, and providing commercial test work and consultancy services to industry. Isabel specialises in DC arc furnace technologies, and has presented papers at several international conferences. Her research interests include DC furnace technology, ferrochromium, ferronickel, slag cleaning, and PGM smelting processes. She obtained a BEng degree in chemical engineering from the University of Pretoria in 1995. Isabel is a registered Professional Engineer with the Engineering Council of South Africa (ECSA), a Fellow and Council member of the Southern African Institute of Mining and Metallurgy (SAIMM), and has worked in the Pyrometallurgy Division of Mintek since 1996.

Her experience includes involvement in test work, process development, and scale-up of DC arc furnaces for ferrochromium, titania slag, ferronickel, the smelting of titaniferous magnetite, recycling of waste materials, and recovery of valuable commodities from discarded slags.

Isabel served as a member of ECSA's Professional Advisory Committee (PAC) for Metallurgical Engineering from March 2010 until 2017.

Isabel is currently the President Elect of the Southern African Institute of Mining and Metallurgy.

Mintek employment history

1. Engineer-in-training, March 1996 to November 1996 (Training position)
2. Engineer, December 1996 to November 1997 (Junior research engineer, team member on large and complex projects, responsible for small projects, execution and reporting)
3. Senior Engineer, December 1997 to October 1998 (Senior research engineer, responsible for large projects, execution and reporting)
4. Principal Engineer, November 1998 to March 2001 (Research engineer with high-level responsibility for large, complex pilot-plant projects)
5. Chief Engineer, April 2001 to November 2005 (High-level and complex projects, interaction with clients, and input in testwork and process design)
6. Head: Commercial Applications, December 2005 to August 2013 (Responsible for commercial testwork projects, management of junior staff, marketing, commercial budgets, and divisional targets)
7. Manager, 1 September 2013 to current (Responsible for divisional budget (>R80M), technical and business strategy, and staff complement of 122)


1. Mintek APEX Award – Enviroplas Process for EAF Dust Treatment (1997)
2. Mintek APEX Award – Development of the Mintek Thermal Magnesium Process (MTMP) (2005)
3. Mintek APEX Award – Development of the Bay 2 PGM ConSmelt (2005)
4. Mintek APEX Award – Technology transfer for the DC-arc recovery of cobalt from slag at Chambishi (2006)
5. Certificate of Merit from The Southern African Institute of Mining and Metallurgy for transaction paper published in October 2009 SAIMM Journal entitled “Recovery of base metals and PGMs in a DC alloy-smelting furnace”, 11 August 2010
6. Finalist for an NSTF Award – Recognizing an outstanding contribution to Science, Engineering, Technology and Innovation (ConRoast), (Research for innovation by a team or individual in a corporate organization – May 2010
7. Mintek APEX Award – Development – Demonstration smelting of two new chromite ores in a DC furnace (2011)
8. Mintek APEX Award – Technology transfer for the twin-electrode DC arc furnace at Koniambo (2013)

List of publications

1.     Kotzé (Geldenhuys) I.J., Pilot plant production of ferronickel from nickel oxide ores and dusts in a DC arc furnace, Pyrometallurgy 02, Mount Nelson Hotel, Cape Town, South Africa, 11-12 March 2002.

2.     Jones R.T. & Kotzé (Geldenhuys) I.J., DC arc smelting of difficult PGM-containing feed materials, International Platinum Conference, ‘Platinum Adding Value’, The South African Institute of Mining and Metallurgy, Sun City, South Africa, 3-7 October 2004, pp.33-36.

3.     Reinecke (Geldenhuys) I.J.& Lagendijk H., A twin-cathode DC arc smelting test at Mintek to demonstrate the feasibility of smelting FeNi from calcine prepared from siliceous laterite ores from Kazakhstan for Oriel Resources plc, Infacon XI, New Delhi, India, 2007.

4.     McCullough S.D., Geldenhuys I.J., & Jones R.T., Pyrometallurgical iron removal from a PGM-containing alloy, Third International Platinum Conference, ‘Platinum in Transformation’, The Southern African Institute of Mining and Metallurgy, Sun City, 5-9 October 2008, pp.169-176.

5 .     Geldenhuys I.J. & Jones R.T., Four years of DC arc smelting of PGM-containing oxide feed materials at Mintek, Pyrometallurgy of Nickel and Cobalt 2009, 48th Annual Conference of Metallurgists of CIM, Sudbury, Ontario, Canada, 23–26 August 2009, pp.415-427.

6.     Marx F., Shapiro M., Fowler N., Gray N.B., & Geldenhuys I.J., Composite Furnace Modules – Application in DC furnaces for FeNi alloy production, Proceedings of the European Metallurgical Conference (EMC 2009), 2009.

7.     Jones R.T., Geldenhuys I.J., & Reynolds Q.G., Recovery of base metals and PGMs in a DC alloy-smelting furnace, SAIMM Journal, Vol.109, No.10, October 2009, pp.587-592.
This paper was awarded a certificate of merit by the Southern African Institute of Mining and Metallurgy for publication in the October 2009 issue of the SAIMM Journal.

8.     Jones R.T. & Geldenhuys I.J., The pros and cons of reductive matte smelting for PGMs, Minerals Engineering, Volume 24 (2011), pp.495-498. (Presented at Precious Metals ’10, Falmouth, 15-16 June 2010.)

9.     Geldenhuys I.J., Refractory erosion during reductive PGM matte smelting (Presentation only), SAIMM Refractory Conference, Misty Hills, Muldersdrift, 16-17 March 2010.

10.     Geldenhuys I.J. & Jones R.T., What scale should your smelting testwork be done at, and what do you get for the money you spend?, Sixth Southern African Base Metals Conference, The Southern African Institute of Mining and Metallurgy, 18-20 July 2011, Phalaborwa, South Africa, pp.477-492.

11.     Geldenhuys I.J., Aspects of DC chromite smelting at Mintek – an overview (Plenary address), Thirteenth International Ferroalloys Conference (Infacon XIII), Almaty, Kazakhstan, 9-13 June 2013, pp.31-47.

12.     Geldenhuys I.J., The exact art and subtle science of DC smelting: Practical perspectives on the hot zone, JOM, Published online: 9 November 2016, 8 pp.

13.     Erwee M.W., Geldenhuys I.J., Sitefane M.B., & Masipa M., Fluxing of South African chromite ore with colemanite, SAIMM Journal, Vol.118, No.6, June 2018, pp.661-670.

14.     Geldenhuys I.J., Feasibility of fluxless smelting of titaniferous magnetite ore in a pilot-plant open-arc DC furnace, MEng Thesis, Stellenbosch University, March 2020.

15.     Geldenhuys I.J., Reynolds Q.G., & Akdogan G., Evaluation of titania-rich slag produced from titaniferous magnetite under fluxless smelting conditions, JOM, Published online: 3 August 2020, 10 pp.

16.     Geldenhuys I.J., Pilot plant smelting of Canadian and South African chromite in a DC furnace, Rodney Jones Honorary Symposium on Chromite Smelting, 59th Conference of Metallurgists, COM 2020, Virtual Conference, Canada, 14-15 October 2020, 13 pp.

Copyright © 1996-2020, Isabel Geldenhuys,, Randburg, South Africa (Last updated on 16 October 2020)

Pyrometallurgy Division, Mintek, 200 Malibongwe Drive, Private Bag X3015, Randburg, 2125, South Africa
Phone: +27-11-709-4629