How Is Platinum Metal Produced?

Platinum grain produced by Anglo American. Image c/o Vismedia

Although platinum most often naturally occurs in placer deposits, platinum and platinum group metal (PGM) miners usually extract the metal from sperrylite and cooperite, two platinum containing ores.

Platinum is always found alongside other PGMs. In South Africa's Bushveld complex and a limited number of other ore bodies, PGMs occur in sufficient quantities so as to make it economical to exclusively extract these metals; whereas, at Russia's Norilsk and Canada's Sudbury deposits platinum and other PGMs are extracted as by-products of nickel and copper.

Extracting platinum from ore is both capital and labor intensive. It can take up to 6 months and 7 to 12 tons of ore to produce one troy ounce (31.135g) of pure platinum.

The first step in this process is to crush platinum containing ore and immerse it in reagent containing water; a process known as 'froth flotation'. During flotation, air is pumped through the ore-water slurry. Platinum particles chemically attach on to the oxygen and rise to the surface in a froth that is skimmed off for further refining.

Once dried, the concentrated powder still contains less than 1% platinum. It is then heated to over 2732F° (1500C°) in electric furnaces and air is blown through again, removing iron and sulphur impurities.

Electrolytic and chemical techniques are employed to extract nickel, copper and cobalt, resulting in a concentrate of 15-20% PGMs.

Aqua regia (a concoction of nitric acid and hydrochloric acid) is used to dissolve platinum metal from the mineral concentrate by creating chlorine that attaches to platinum to form chloroplatinic acid.

In the final step, ammonium chloride is used to convert the chloroplatinic acid to ammonium hexachloroplatinate, which can be burned to form pure platinum metal.

The good news is that not all platinum is produced from primary sources in this long and expensive process. According to United States Geological Survey (USGS) statistics, about 30% of the 8.53 million ounces of platinum produced worldwide in 2012 came from recycled sources.

With its resources centered at the Bushveld complex, South Africa is by far the largest producer of platinum, supplying over 75% of world demand, while Russia (25 tonnes) and Zimbabwe (7.8 tonnes) are also large producers. Anglo Platinum (Amplats), Norilsk Nickel and Impala Platinum (Implats) are the largest individual producers of platinum metal.

Sources:
Wood, Ian. 2004. Platinum. Benchmark Books (New York).
The International Platinum Group Metals Association (IPA).
Source: http://www.ipa-news.com/
USGS: Platinum Group Metals.
Source: http://minerals.usgs.gov/minerals/pubs/commodity/platinum/

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