# Commercial recovery of PGMs in South Africa



## Irons (Dec 6, 2007)

http://www.platinum.matthey.com/production/africa.html

--snip--

Concentration

The ore is crushed and milled to reduce the size of the rock particles and to expose the minerals which contain the pgm. The particles are mixed with water and special reagents and air is pumped through the liquid, creating bubbles to which the pgm-containing particles adhere. These float to the surface and are removed as a soapy froth. The pgm content of this flotation concentrate varies between 100 and 1,000 grams per tonne.

After being dried, the concentrate is smelted in an electric furnace at temperatures which can exceed 1,500ºC. During this process, a matte containing the valuable metals is separated from the unwanted minerals, which form a slag and are discarded. The matte is transferred to converters, where air is blown through it in order to remove iron and sulphur. The pgm content of the "converter matte" now exceeds 1,400 grams per tonne.
Refining

The next step is to separate base metals from the pgm. The final stage is the separation and purification of the six pgm, plus gold and small amounts of silver. The soluble metals - gold, palladium and platinum, which dissolve in hydrochloric acid and chlorine gas - are generally the first to be extracted, in that order. The insoluble pgm come out next, with rhodium usually last.

The refined pgm have a purity of over 99.95 per cent, and can be produced in a number of forms: ingot, grain or a fine powder known as "sponge". The time between mining of the ore and production of pure metal typically ranges from around 6 weeks for palladium to up to 20 weeks for rhodium.


----------

