Northam first produced PGMs from the Merensky reef at the Zondereinde mine in 1993.
With the UG2 expansion project in 2000, Zondereinde started mining the UG2 reef and built and commissioned the R80 million UG2 concentrator plant. With relatively few reef disturbances on the UG2 reef horizon, mining conditions are easier. As a result the UG2 reef is now extensively mined, with a drive to maximise production and processing in order to take advantage of the buoyant markets for PGMs.
Merensky and UG2 ores are processed separately in the two plants (which are designed to treat sulphide ores), with the concentrate from both blended in slurry form in the feed tank prior to filtration and drying at the smelter from which granulated converter matte is fed to the base metals removal plant (BMR). In the BMR, nickel (Ni) and copper metals (Cu) are removed as crystalline nickel sulphate and copper cathode which are transported directly to local consumers for further beneficiation.
The remaining PGM solutions are filtered and dried to produce a final concentrate ready for shipment to the Heraeus refinery. The concentrate is weighed and drummed. At Hanau the material is toll-refined to final metal purity of 99.95%. Northam then sells refined metal to contractual metal customers at various global destinations.
The introduction of an external sparger column cell as a final concentrate cleaner in the company's UG2 concentrator plant has been a successful innovation.
|Description||Date of commissioning||Capacity||Current volume throughout||Function||Current recovery|
|Merensky concentrator||1993||150 000tpm||100 000tpm||Crushing, milling, floatation||88%|
|UG2 concentrator||2000||105 000tpm||94 000tpm||Crushing, milling, floatation||86%|
|Smelter||1993 (rebuilt in 2008. Next schedule rebuild between 2013 and 2018)||15MW||10MW||Drying, smelting, converting||99%|
|Base metals removal plant||1993||360tpm matte||330-340tpm||Atmospheric and pressure leach||98.2% (PDM) 99.8% (Nickel)|