Marikana Platinum Mine, South Africa

The Marikana mine is located in the North West Province of South Africa, approximately 8km east of the Kroondal mine. Commissioned in late 2002 at an investment of R360m, the mine is a 50/50 partnership between Aquarius Platinum (South Africa) (AQPSA) and Anglo Platinum. It is the second operational mine of AQPSA in South Africa. In 2006, AQPSA entered into a second pool and share agreement (P&SA2) with Anglo Platinum that led to the launch of a dense media separation (DMS) plant in the following November.

The mine includes two ore bodies and has estimated life up to 2020. In 2009, production at the mine reached 157,937 PGM oz. In July 2010, operations at the mine were suspended following an accident that resulted in the death of five miners. Mining operations resumed on 23 July 2010 after a safety audit was carried out at shaft four of the Marikana mine.

Reserves

The mine holds an estimated 2.47m 4E oz of mineral resources and 1.6m 4E oz of mineral reserves. Proven reserves from the Marikana and the shaft four ore body amounted to 2.64Mt in the open pit and 21.3Mt in the underground graded at 3.76g/t and 3.24g/t Pt+Pd+Rh+Au respectively. Probable reserves total 0.79Mt and 5.07Mt in the open pit and underground respectively. Total measured, indicated and inferred resources are estimated to be 30.17Mt at a grade of 5.09g/t Pt+Pd+Rh+Au. This includes 10.69Mt graded at 3.63g/t Pt+Pd+Rh+Au from the Marikana orebody and 19.48Mt from the shaft four ore body that is graded at 5.9g/t Pt+Pd+Rh+Au.

Marikana geology

The mine combines the Marikana and the shaft four ore bodies. The Marikana is a basin-type open pit ore body that measures 1.5km in length and 3km in width.

The structure dips at the centre at 10° and 20° from all sides and has a maximum depth of about 200m. The topography of the surface is flat with a gentle slope towards the north. The ore body is faulted and characterised by dykes.

The shaft four ore body, hosted adjacent to the Kroondal block, is geologically similar to the UG2 that dips approximately 9° northwards. The ore body is characterised by dykes and pillars.

It is composed of two mineralised seams including the Main and Leader seams. A 1m pyroxenite zone referred to as a parting separates both the seams.

Mining and processing

The mine has gradually moved from open cast to underground mining. In 2009, ramp-up of underground production progressed well. The underground mine is accessed through two decline shafts namely shaft one and shaft four.

The third underground decline shaft (shaft two) was closed in 2009 due to its geological constraints and lack of critical mass.

Open pit mining was carried out along the dip during the year, reflecting the changes made in open pit mining methods as well as the shape of the pit in 2008. Intended to optimise production from open pit, the changes resulted in maintaining the stripping ratio at 28:1. Earlier, ore from the open pit had been mined till a depth of 100m.

Processing is carried in a 220,000tpm on-site concentrator plant. Smelting, refining and marketing of the produced platinum in concentrate are carried out by Anglo Platinum and Impala Refining Services.

Production

In 2009, the mine reported an increase of 27% in the total tons mined that stood at 2.6Mt including 1.2Mt from open pit and 1.4Mt from underground operations.

By the end of the year, production from underground operations accounted for 54% while open pit production had amounted to 43%.

The average head grade during the year decreased to 2.84g/t from 2.89g/t. Due to loss of face length, production was carried out in a constrained manner, in order to limit geological losses.