Platinum is produced in five countries in the world. Of these, South Africa is by far the largest producer, accounting for over 75% of global output in 2008, reports Creamer Media’s Research Channel Africa.
In second position is Russia, which produced almost 14% of global platinum output in 2008, followed by Canada, the US and Zimbabwe.
Platinum experts Johnson Matthey show South Africa to have produced 4,78-million ounces of platinum in 2008, which was 5% down on the country’s platinum production in 2007.
Research Channel Africa states that the country’s platinum-mining operations are concentrated on the extremely large, two-billion-year-old, saucer-shaped, layered igneous intrusion, known as the Bushveld Complex, which occurs in the northern part of the country, traversing the North West, Limpopo and Mpumalanga provinces.
Professor Grant Cawthorn indicates, in a paper on the platinum and palladium resources of the Bushveld Complex published in the South African Journal of Science, that it is generally understood that the Bushveld Complex was formed by the repeated injection of magma into an enormous chamber. Owing to the huge volumes of magma involved, cooling and subsequent mineral crystallisation out of the magma was a slow process. Different minerals were formed as the magma cooled. These minerals accumulated into subhorizontal layers, building from the base of the chamber. The processes were repeated by the intermittent replenishment and the addition of existing and new magma as the case may be, producing a repetitive mineral layering.
Mining company Impala Platinum (Implats), in its review of the geology of the Bushveld Complex, indicates that individual layers or groups of layers of the Bushveld Complex can be traced for hundreds of kilometres. This layered sequence, the Rustenburg Layered Suite, comprises five principal zones, the marginal, lower, critical, main and upper zones. The Bushveld Complex is, horizontally, roughly clover-leaf shaped, consisting of four compartments or limbs – western, eastern, northern and southern in order of economic importance.
Research Channel Africa states that the Bushveld Complex is distinctive in size, covering an aerial extent of some 66 000 km2, and distinctive in the economic importance of its minerals. Contained within the well- layered ultramafic to mafic succession are two horizons in the critical zone that host economically exploitable quantities of platinum-group metals (PGMs), namely the Merensky reef and the underlying upper group two (UG2) reef. These two economic horizons can be traced for 370 km around the complex and are the focus of mining operations from which the PGMs – platinum, palladium, rhodium, ruthenium and iridium – are recovered, together with quantities of gold, nickel, copper and numerous other metals and compounds. Below the UG2 reef are numerous other chromitite layers that are mined for chro- mium, as their PGMs content is too low.
A third PGMs-rich ore body, the Platreef, which extends over a distance of 30 km, is found only on the northern limb, in the vicinity of Mokopane, in Limpopo province. This ore body, first mined in the 1920s, was not exploited on a large scale until 1993.
Johnson Matthey indicates that Russia produced 855 000 oz of platinum in 2008, which was down on the 910 000 oz produced in 2007.
Research Channel Africa states that platinum-mining in Russia can be traced back to 1823 when large alluvial platinum deposits were discovered in the central Ural mountains. By the end of the nineteenth century, these alluvial deposits had become the world’s dominant source of platinum.
By the late 1920s, however, the most easily accessible high-grade placer deposits had largely been exhausted and mining has since dwindled to a handful of small-scale dredging operations producing very modest quantities of platinum.
Johnson Matthey reports that there is a renewed interest in the Urals as a potential future source of platinum. Modern extraction methods may make the exploitation of previously overlooked alluvial and placer deposits possible.
Research Channel Africa reports that almost all of Russia’s PGMs are supplied by three mining companies and from State reserves. State PGMs stocks remain a State secret, and nearly all PGMs in State stocks are believed to have been mined by metals giant Norilsk Nickel.
Norilsk Nickel dominates Russian PGMs output, producing platinum, palladium and other minor PGMs from its copper/nickel mining and smelting complex in northern Siberia. Small volumes of PGMs are also produced from its copper/nickel mines in the Kola Peninsula. Norilsk Nickel accounts for 46,3% of the world’s palladium market and 12% of the market for platinum. In 2008, Norilsk Nickel produced 2,82-million ounces of palladium and 659 000 oz of platinum.
The company’s northern Siberian facilities form the basis of its Polar Division, which is situated on the Taimyr Peninsula. This division operates seven nickel/copper mines and associated metallurgical plants at Norilsk-Talnakh. Deposits mined at Norilsk-Talnakh are unique in size and unusually rich in PGMs. Johnson Matthey estimates that the head grades at the Norilsk-Talnakh mines are about 10 g/t. In addition, the deposits are considerably wider than the narrow, continuous reef mined in South Africa, but much more variable in grade and composition.
Other sources of platinum production include two alluvial mining operations in the Russian Far East. The first and larger of the two operations, the Kondyor mine, is located in the Ayano-Maisk region of Khabarovsk. Commercial exploitation of the deposit by a local gold-mining company, the Amur artel, began in 1984. The smaller Koryak deposit is situated in Kamchatka on the Pustaya river system, which drains an area of PGMs-bearing zoned ultrabasic rocks. Full-scale mining of the deposit by the Chaibukha mining cartel, in conjunction with Koryakgeolodobycha, started in 1995.
Research Channel Africa states that in December 2008, it was reported that Russian President Dmitry Medvedev had signed into law a bill abolishing State firm Almazjuvelirexport’s monopoly on exporting PGMs. Previously, all PGMs producers and stock holders, including the world’s largest palladium-miner Norilsk Nickel, the Central Bank, and State precious metals and gems repository Gokhran, had to export the metals through precious metals and stones exporter Almazjuvelirexport for a fee. The Russian government believes that the move was necessary as part of the process of liberalising Russia’s previously secret PGMs market. The bill took about four years to pass through both chambers of parliament.
Johnson Matthey reports that platinum production in North America in 2008, at 340 000 oz, was up on the previous year’s production of 325 000 oz. However, palladium supplies fell by 4% to 950 000 oz, reflecting lower production from Stillwater, in the US and North American Palladium, in Canada.
Historically, according to Johnson Matthey, PGMs have been produced as by-products of nickel and copper mining in Canada. As recently as the 1940s, the nickel deposits of the Sudbury Basin were the world’s largest single source of PGMs, and these deposits still produce substantial quantities of metal. Palladium accounts for between 55% and 60% of the PGMs content of the Sudbury ores, with the remainder being platinum, while the rhodium content is small.
Research Channel Africa reports that commercial production of PGMs began in about 1908 when the largest mining com- pany in the Sudbury Basin, Vale Inco, opened a refinery in the UK to refine the Sudbury ores. The other major producer in Ontario, Falconbridge, produces PGMs at its refinery in Norway. Both companies were the subject of acquisitions in 2006, with Vale Inco now owned by the Brazilian base metals pro- ducer Vale and Falconbridge by the Swiss diversified mining company Xstrata.
Another significant source of by-product PGMs is Falconbridge’s Raglan mine, situated on the Ungava peninsula, in the far north of Quebec.
Johnson Matthey reports that the only existing primary source of PGMs in Canada, the Lac des Iles mine, owned by North American Palladium, is located near Thunder Bay, in western Ontario. Commercial production of PGMs began in 1993 from the deposit known as the Roby Zone which, until recently, was exploited exclusively through openpit mining. In 2005, an underground section was developed to exploit a deeper, higher-grade section of the deposit. Ore from the mine is processed to a concentrate rich in palladium, while also containing small amounts of platinum and base metals.
The US has only one primary PGMs producer, the Stillwater Mining Company, which conducts mining operations at the Stillwater mine near Nye, Montana, and at the East Boulder mine, south of McLeod, Montana. Both mines are located on the Johns-Manville reef, which is possibly the richest PGMs deposit currently being exploited anywhere in the world. The mill head grade is typically between 20 g/t and 24 g/t, with a platinum-to-palladium ratio of one to three.
Johnson Matthey indicates that Zimbabwe produced 305 000 oz of platinum in 2008, which was up on the previous year’s production of 290 000 oz.
Research Channel Africa states that platinum-mining in Zimbabwe is centred around the Great Dyke, a 550-km layered geological intrusion, with mineralisation occurring in four elliptical bodies with a total strike length of 350 km, running in a north-south direction through the heart of the country. The PGMs occur in a layer known as the Main Sulphide Zone, which is typically about 3 m thick. However, the economic mining width may be as little as one metre, depending on grade, metal prices and the chosen mining method.
According to Cawthorn, PGMs grades, at about 3 g/t, are lower than in the Bushveld Complex, but the ratio of platinum to palladium is relatively high compared with most ores. In contrast, nickel and copper values are typically higher than those found in South African platinum ores. Zimbabwe’s platinum resources are estimated at 143-million ounces.
Research Channel Africa reports that Zimbabwe’s ongoing political instability and the associated economic crisis have largely brought mining in the country to a halt. However, the country’s platinum mines continue to operate, although not at full capacity. Implats, the world’s second-largest platinum producer, has platinum-mining interests in Zimbabwe. The company has a controlling stake in PGMs producer Zimplats, which operates an openpit and underground section at Ngezi, and a 50% shareholding in the Mimosa mine with platinum junior Aquarius Platinum. A third platinum mine, Anglo Platinum’s Unki project, is being developed near Gweru. When fully operational, the mine is expected to process about 120 000 t/m of ore.