SA research on new ways to refine zinc The Africa Desk of the International Zinc Association (IZA) has secured funding from Vedanta SA and Duferco Steel Processing for research on new clean, green and low-energy zinc refining, which may result in a new zinc refinery in the Saldanha Bay IDZ. T he International Zinc Association (IZA) Africa Desk is tasked with re - vitalising the zinc industry in South Africa by increasing awareness and
benefits of zinc and its applications, ultimately to increase uptake. As part of this mission, the Africa Desk has secured significant research funding to investigate the feasibility of new zinc refining processes to meet South Africa’s own demand for refined zinc, whilst using lo - cally produced ore and concentrates. Should the research develop a winning chemical engineering solution, then an ideal location for a new zinc refinery could be Saldanha Bay, which is an Industrial Development Zone (IDZ) on the doorstep of a zinc ore export port and close to a big refined-zinc user. “The funding has been secured from within South Africa. The sponsors are very keen to see that we can develop our own capability within South Africa to produce special high- grade refined zinc and, at the same time, support a fundamental chemical engineering research and developing postgraduate pro- gramme,” reports IZA Africa Desk spokesper- son Simon Norton. Two industrial sponsors are participating in the project, namely Vedanta South Africa, an IZA member, and Duferco Steel Processing, which galvanizes steel in Saldanha Bay. “We are very proud of these future-thinking sponsors. Not only are they supporting fun- damental research in South Africa, they are also supporting a ‘green’ future for minerals processing,” emphasises Norton. The research will focus on developing and understanding novel refining processes to significantly reduce the external power input compared to traditional pyrometallurgical processes. This will allow for economically viable production of special high-grade (SHG) refined zinc. Ore beneficiation may be further maximised by producing refined by-products such as silver and rare earth elements. “The proposed operation will also have a consider- ably reduced carbon footprint,” adds Norton. The research work will be carried out at the University of Cape Town (UCT) in its state-of-the-art Department of Chemical Engineering under the leadership of Professor Jochen Petersen. In its proposal, entitled ‘Concept and prefeasibility study of a small- scale zinc refinery in South Africa considering novel processes’, UCT notes that the develop- ment of a small-scale, relatively simple and
The research will be carried out at UCT’s Department of Chemical Engineering under the leadership of Prof Jochen Petersen.
energy-efficient process to recover zinc from polymetallic local concentrates ‘is a consider- able challenge, given the limitations of existing processes’. In support of this ‘back to the drawing board’ approach to novel development processes that have never been commer- cialised to date, IZA Africa Desk launched its campaign for research funding in 2021. The exciting news is that Vedanta South Africa will sponsor a desktop study of a wide variety of zinc processes, while Duferco Steel Processing is funding laboratory-scale research on zinc process chemistry. According to the research team, the ex- perimental study will carefully explore the in-principle feasibility of a novel flowsheet for refined zinc production and by-product re - covery from local ore concentrate materials, with the express emphasis on reduced and/or renewable energy input, as well as reduced carbon and environmental footprints. The driving force behind the research goes back to Exxaro’s Zincor refinery on the East Rand, the only one of its kind in South Africa, which was closed down in 2011. Its yearly production of 117 000 tons of refined zinc was entirely for local consumption by hot dip galvanizers and continuous wire and sheet galvanizers. Applications ranged from shopping centre roofing to underground min - ing steel structures, structural steel, railway
pylons and fencing. Despite Zincor’s output, South Africa still had to import 10 000 t to 20 000 t of additional refined zinc for the country’s galvanizing requirements. Prior to 2011, South African consumption of refined zinc peaked at over 130 000 tons per annum. However, this has now plunged to only 47 000 t in 2020, a significant drop that Norton attributes to a decline in mining, construction and industrial activity in the country. “IZA Africa Desk is thus working hard to get the use of refined zinc growing again in South Africa,” says Norton. Recently, South African galvanizers expe- rienced a severe shortage in the refined zinc supply due to four zinc refineries in Europe closing down. “The situation is compounded by the fact that base metal traders worldwide are selling zinc to Europe at inflated prices, rather than to South Africa at normal market prices,” notes Norton. New zinc process chemistry is critical for investment in zinc refining in South Africa to support the government’s mooted R100-billion Infrastructure Plan. “We have an unreliable power supply in South Africa and urgently need to find novel low-power methods to refine zinc. This also means we have to harness our local research teams, develop our own expertise, and hopefully come up with a zero power ‘green’ zinc refining process,” concludes Norton. www.zinc.org
24 ¦ MechChem Africa • May-June 2022
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