May 2009

Historical Metallurgy

Platinum in Bophuthatswana

By F. Habashi

Four postage stamps commemorating platinum, issued on August 15, 1979, are of particular historical interest. One stamp shows pouring of platinum and an African worker, while other stamps summarize the importance of platinum in the chemical industry, in telecommunications satellites and in jewelry. The stamps were issued by Bophuthatswana, a bantustan (homeland) in the Republic of South Africa. At the time, Bophuthatswana consisted of seven enclaves dispersed in northwest South Africa. The homeland was set up to house Setswana-speaking peoples, with its capital, Mmabatho, situated in an area bordering Botswana. Bophuthatswana was given nominal self-rule in 1971, and became independent on December 6, 1977. A head of state was appointed by the South African government, but the new country was not recognized as independent by any government other than that of South Africa and Israel. In 1983, it had more than 1,430,000 inhabitants. Two attempted coups were suppressed by South Africa.

Bophuthatswana’s wealth came from the number of platinum mines on its soil. The Bushveld Complex is a large igneous intrusion that contains some of the richest ore deposits on earth. The reserves of platinum group metals are the world’s largest, with vast quantities of iron, tin, chromium, titanium and vanadium. The geographic centre of the complex is located north of Pretoria. It covers over 66,000 square kilometres, an area the size of Ireland. The complex varies in thickness, sometimes reaching nine kilometres in thickness.

The ore bodies within the complex include the UG2 Reef, containing up to 43.5 per cent chromite, and the platinum-bearing horizons, the Merensky  and Plat reefs. The Merensky Reef varies from 30 to 90 centimetres in thickness. It is a norite with extensive chromitite and sulphide layers or zones containing the ore. The reef contains an average of 10 ppm platinum group metals in pyrrhotite, pentlandite and pyrite, as well as in rare platinum group minerals and alloys. The Merensky and UG-2 reefs contain approximately 90 per cent of the world’s known PGE reserves. About 80 per cent of the platinum and 20 per cent of the palladium mined each year are produced from these horizons. The initial recovery of platinum took place on several of the large East Rand gold mines; the first separate platinum mine was a short-lived venture that worked small quartz reefs.

The discovery of the Bushveld Igneous Complex deposits was made in 1924 by a district farmer. This was an alluvial deposit but its importance was recognized by Hans Merensky, whose prospecting work discovered the primary source in the Bushveld Igneous Complex, and by 1930, he had traced it for several hundred kilometres. Extensive mining of the reef took place when an upsurge in the demand for platinum group metals, used in exhaust pollution control in the 1950s, made exploitation economically feasible. It was not until the 1970s that major advances in metallurgy made the extraction of metals from the UG2 chromitite possible.

Impala Platinum Limited has its primary operations concentrated on the Impala lease area on the western limb of the Bushveld Complex, near the town of Rustenburg. Some 28,000 people are employed by Impala Platinum. Mining at Impala focuses primarily on two reefs, the Merensky Reef and the UG2 Chromitite Layer, which are contained in the Rustenburg Layered Suite, a well-layered ultramafic to mafic igneous succession of the Bushveld Complex. The majority of mining operations extend to a depth of around 1,000 metres below surface.

Hans Merensky (1871-1952), South Africa’s most famous prospector and mining geologist, was born in Botshabelo, South Africa. He studied at the State Academy of Mining and the University of Berlin, and was a consulting geologist in Johannesburg. While conducting some geological surveys, he discovered tin near Pretoria and reported it to the Premier Diamond mine regarding possible mining prospects. In 1924, he was tipped off about some platinum deposits near Lydenburg. There, he discovered a 48-kilometre reef that was later named for him.

In his later years on his farm, Westfalia, he contributed much to South Africa’s agriculture industry through his research into preventing erosion, new grass types, fruit and animal breeding. During his lifetime, he donated much of his wealth to universities, schools, libraries, hospitals, charities, cultural organizations and people in need. One of his greater contributions was to the University of Stellenbosch, enabling it to create a forestry faculty.

Bophuthatswana also made money from the Sun City Casino, which was a short drive of 150 kilometres from Johannesburg and Pretoria, where gambling was illegal. In the beginning of 1994, when South Africa was heading for democratic elections, the president of Bophuthatswana resisted re-incorporation into South Africa. However, on April 27 of the same year, all ten homelands, including Bophuthatswana, became part of post-apartheid South Africa.

Sun City, which lies deep in the rugged Bushveld, in the heart of an ancient volcano, is a unique resort complex with a spectacular casino, restaurants, swimming pools, botanical gardens and extensive sporting facilities, including two world-class golf courses.

In conclusion, postage stamps are an important means of communication; numerous countries have recorded important events, honoured worthy individuals and described interesting facts through this medium. Many historical facts, sometimes obscure, can be found on stamps; some of these may not be easily located in a history or a science book. Stamps have artistic value, they are used every day and can be found everywhere.

Suggested Readings

F. Habashi, D. Hendricker, & C. Gignac (1999). Mining and Metallurgy on Postage Stamps. Quebec City: Métallurgie Extractive Québec/Laval University Bookstore.

O. Lehmann (1959). Look Byond the Wind, the Life of Dr. Hans Merensky. Cape Town:
Howard Timmins.

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