Minerals Engineering 23 (2010) 438–450 Contents lists available at ScienceDirect Minerals Engineering journal homepage: www.elsevier.com/locate/mineng The environmental costs of platinum–PGM mining and sustainability: Is the glass half-full or half-empty? Bonnie J. Glaister, Gavin M. Mudd * Environmental Engineering, Department of Civil Engineering, Monash University, Clayton 3800, Melbourne, Australia article info abstract Article history: The growing popularity of platinum group metals (or PGMs, including platinum and palladium) for a Received 6 August 2009 wide range of applications leads to some interesting issues for mining and sustainability. The uses of Accepted 16 December 2009 PGMs includes catalytic converters for air pollution control in vehicles, growing jewellery use, catalysts Available online 4 February 2010 for various purposes (especially petroleum and chemicals processing), hydrogen fuel cells, and many oth- ers. Given the growing importance of most of these PGM uses in more sustainable technologies or in mak- Keywords: ing industrial processes more efficient, it is critical to understand the complex sustainability issues which Platinum surround PGMs. At present, South Africa is the dominant PGMs producer and holds 88% of estimated Palladium global resources, with additional production and resources in Russia, Zimbabwe, Canada and the United Mineral resources Sustainable mining States. Given the concentrated location of PGM resources, what are the likely trends in PGM mining with Resource intensity respect to environmental sustainability? That is, what are the costs in terms of energy, pollution, green- Greenhouse gas emissions house gas emissions, water, land use impacts, social impacts, economic aspects associated with this glob- Energy intensity ally important industry? This paper compiles and analyses a range of data on PGM mining. It synthesizes a unique combination of data which relates typical production aspects such as ore grade and scale with sustainability aspects such as greenhouse, energy and water costs. The findings are critical in understand- ing the debate about the increasing environmental and social costs of some materials and technologies which are considered crucial for sustainable technologies based on PGMs. Overall, the paper represents a valuable insight into the environmental and resource sustainability of the PGM sector. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction impacts such as water pollution, unfair village relocation, eco- nomic disparity and compensation issues (amongst others) (Curtis, Platinum group metals (PGMs) possess a range of unique chem- 2008; Rajak, 2008; Mnwana and Akpan, 2009). ical and physical properties and are increasingly finding important This paper presents a detailed review of the PGM industry and uses in a wide variety of environmentally-related technologies. The major environmental costs such as water, energy and greenhouse use of PGMs consists of catalysts for chemical process facilities gas emissions (GGEs), focusing primarily on South Africa as a case (especially oil refineries), catalytic converters for exhaust control study. A range of data are compiled, including annual production in transport vehicles, hydrogen fuel cells, electronic components, statistics, major inputs and outputs, and analysed with respect to and a variety of specialty medical uses, amongst others. Given unit efficiencies or ‘sustainability metrics’. The relationships be- the need to expand almost all of these uses to meet environmental tween production statistics and sustainability metrics are then challenges, demand growth for PGMs can reasonably be expected investigated with a view to understanding the current trends in to be sustained long into the future. PGM mining and potential future implications. Although social im- The global production of PGMs is dominated by South Africa pacts are crucial in sustainability, they are outside the scope of this due to their large economic PGM resources in the Bushveld Com- paper. The paper presents a unique case study for a group of metals plex, while other countries such as Russia, Canada, Zimbabwe, which are uniquely concentrated in one major region of the earth and the United States play a minor but important role. Concerns and pose some intriguing and difficult sustainability issues for are being raised, however, about the long term ability to supply the future. PGMs to meet future technological needs (e.g. Gordon et al., 2006), as well as allegations of significant environmental and social 2. Review of platinum–PGM mining and processing * Corresponding author. Tel.: +61 3 9905 1352. The platinum group is made up of six closely related metals E-mail address: [email protected] (G.M. Mudd). with similar physical and chemical properties (Vermaak, 1995). 0892-6875/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.mineng.2009.12.007 B.J. Glaister, G.M. Mudd / Minerals Engineering 23 (2010) 438–450 439 They are divided according to their densities into a heavier cate- Table 1 gory, comprising platinum (Pt), iridium (Ir) and osmium (Os), PGM production and resources in 2007 by country (Loferski, 2008; USGS, 2009). and a lighter group, consisting of palladium (Pd), rhodium (Rh), Country Production Reservesb Reserve baseb and ruthenium (Ru). Due to their high corrosion and oxidation t Pt t Pd t PGM t PGM t PGM resistance, along with Au and silver, PGMs are classified as noble South Africa 165.83 86.46 310.92 63,000 70,000 metals. In addition, the relatively low average concentration and Russia 27.00 96.80 138.30 6200 6600 overall scarcity of PGMs in the earth’s crust leads to them being Canada 6.20 10.50 20.20 310 390 considered as precious metals. Common abbreviations used are Zimbabwe 5.30 4.20 11.00 – – ‘4E’ which includes Pt, Pd, Rh and Au (3E + Au), while 6E includes United States 3.86 12.80 – 900 2000 Pt, Pd, Rh, Ru, Ir and Au (5E + Au). Columbia 1.40 – – – – Australia 0.90a 0.73a –– – In 2007, global PGM production was 509 t, consisting of 165.8 t Pt and 86.5 Pd from South Africa, 27 t Pt and 96.8 t Pd from Russia, World 212 219 509 71,000 80,000 6.2 t Pt and 10.5 t Pd from Canada, 5.3 t Pt and 4.2 t Pd from Zim- a Assuming Australia is credited for PGMs extracted from ores and concentrates babwe and 3.9 t Pt and 12.8 t Pd from the United States (Loferski, exported to Japan. b 2008). Historical production and price is shown in Fig. 1, with See USGS (2009) for detailed definitions, but they are broadly similar to reserves and resources as used in Australia, Canada, South Africa and elsewhere. 2007 production and economic resources given in Table 1. The PGMs are one of the few metals which have stayed relatively con- Placer deposits – alluvial sedimentary deposits containing stant in their real price over time (Kelly and Matos, 2009), despite coarse PGMs (commonly Pt) were mined in conjunction with strong production growth since 1960. alluvial Au for some 2000 years prior to the 20th century. Columbia has long been a major source of alluvial-derived Pt, 2.1. Platinum–PGM mining and processing producing about 1.4 t Pt in 2007 (the major placer source). There are broadly considered to be four main types of economic The mining of PGM ores is through conventional underground PGM ores (Vermaak, 1995; Cabri, 2002): or open cut techniques. The next stage is grinding and gravity- based (or dense media) separation, followed by flotation to pro- Stratiform deposits – where PGMs occur in large Precambrian duce a PGM-rich concentrate. The run-of-mine ore grades are typ- mafic to ultramafic layered intrusions. The major examples ically several g/t, while concentrates are some hundreds of g/t include the Merensky and Upper Group 2 (UG2) Reefs of (Vermaak, 1995). Concentrate is then smelted to produce a PGM- the Bushveld Complex, South Africa, the Great Dyke in Zimba- rich Ni–Cu matte, with the PGMs extracted and purified at a pre- bwe and the Stillwater complex in Montana, United States. cious metals refinery (including Ni–Cu by-products). The process- These deposits are usually considered primary due to their ing is therefore more analogous to base metals rather than Au, size (10–1000 Mt) and grade (3–10 g/t PGMs, 0.2–1% which relies on cyanide leaching and hydrometallurgy. Smelting Ni + Cu). of concentrates from Ni–Cu mining can also be a moderate source Norite intrusions – where meteoritic impact is considered to of PGMs (e.g. Russia, Canada). Further details on PGM ore process- have been instrumental in allowing PGM emplacement. The ing are given by Vermaak (1995) and Cabri (2002). major example is the Sudbury Irruptive complex in Ontario, Canada (10–1000 Mt, 1–3 g/t PGMs, 2–3% Ni + Cu). Ni–Cu bearing sills – related to rift structures, allowing concor- 2.2. The Bushveld Complex, South Africa dant intrusive sheets. The best known examples are the Nor’ilsk- Talnakh District in Russia and the Jinchuan deposits in China The North West province of South Africa hosts the Bushveld (10–1000 Mt, 2–15 g/t PGMs, 3–5% Ni + Cu). Complex, a large igneous complex about 370 km east–west and 500 35.000 United US$/kg PGM States 30.000 1998 US$/kg PGM 25.000 400 20.000 15.000 300 PGM) (US$/kg Price 10.000 5.000 200 0 1900 1920 1940 1960 1980 2000 Russia Annual PGM Production (t) PGM Production Annual 100 South Africa Canada 0 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Fig. 1. Historical PGM production and price (inset) (data combined from Vermaak, 1995; Loferski, 2008; CMSA, 2008; Kelly and Matos, 2009; NRC, 1944–2008; SADME, 2007). 440 B.J. Glaister, G.M. Mudd / Minerals Engineering 23 (2010) 438–450 up to 240 km north–south (Vermaak, 1995).