Tharisa Mine

Low-cost producer of both PGM and chrome concentrate.

Tharisa Mine is a shallow and large-scale open pit PGM and chrome mine that has an estimated open pit life of approximately 18 years and an estimated further 40 years underground and has been in production since November 2009.

Geology

Significant resource of 877.7 million tonnes located in the Bushveld Complex.

The Tharisa Mine is located on the south-western limb of the Bushveld Complex. It is located approximately 95 kilometres north-west of Johannesburg and 35 kilometres east of Rustenburg, and is supported by well-developed infrastructure.

According to Coffey Mining, the Bushveld Complex contains 56% of the world’s known PGM resources and over 68% of the world’s total economically viable chromite reserves. The mining rights held in respect of the Tharisa Mine cover an area of approximately 5,475 hectares on the farms 342 JQ and Rooikoppies 297 JQ in the Marikana district. The Tharisa Mine has a deposit with an outcrop strike length of approximately five kilometres across the 342 JQ farm.

The Tharisa Mine is underlain by four principal mineral-rich layers, known as the Middle Group Chromitite layers. From the outcrop the layers dip to the north across the remainder of 342 JQ and into Rooikoppies at an angle of approximately 12 to 15 degrees to a depth of over 1,000 metres. The Middle Group Chromitite Layers are initially capable of being mined with open pit mining of 18 years, requiring underground mining for 40 years as the layers dip away to the north.

Mining

Open pit mining operations will continue until 2036 and then transition to underground mining.

Based on a maximum 200 m highwall, the life of pit and a 400 ktpm production profile, it is expected that open pit mining operations will continue until 2036 and that the transition to underground mining will commence in 2050, initially in targeted layers. The open pit design and schedule has been completed and a mining method selection study was undertaken to evaluate various methods for the future underground mining operations. The bord-and-pillar method was selected on the basis of its faster development, greater flexibility, enhanced safety and efficiency. Underground mining operations are planned to increase in line with the reduction in open pit production and to take place to depths of up to 750 m until 2065.

Large scale open pit mining has traditionally been conducted by specialist mining contractors.

In April 2017, Tharisa announced its plans to transition from contractor to an owner mining model. Tharisa is in the process of acquiring the mining fleet and transferring employees from the existing mining contractor. The transition in operating model is expected to be completed with-in FY2017.

Processing

Tharisa Minerals’ two independent processing plants are designed specifically to treat the MG Chromitite Layers of the Bushveld Complex.

The smaller 1.2 Mtpa Genesis Plant came on stream first, with the 100 ktpm chrome circuit being commissioned in August 2011 and the PGM circuit being commissioned in December 2011 and the larger 3.6 Mtpa Voyager Plant was commissioned in December 2012. The plants have a
similar process flow that includes crushing and grinding, primary removal of chrome concentrate from spirals, followed by PGM flotation from the chrome tails and a second spiral recovery of chrome from the PGM tails.

Operating in parallel, the independent plants provide processing flexibility and production stability by allowing one plant to be shut down without hampering the production of the other.

Using off-the-shelf technology, the processing circuits are uniquely engineered to deliver both PGM and chrome production. This innovative approach to production has made Tharisa a world-class PGM and chrome co-producer.

The Group’s initial development plan for the construction and ramp up of its processing facilities comprised three phases:

Plant feed

PGM production
Chrome production
  KEY MILESTONES COMPLETION DATE
  Phase 1   Trial mining and construction of the pilot-scale Genesis Plant with chrome processing capacity of 38 ktpm November 2009
  Phase 2   Increase in chrome processing capacity at Genesis Plant to 100 ktpm August 2011
      Commissioning of  PGM processing capacity at the Genesis Plant December 2011
  Phase 3   Commissioning of 300 ktpm Voyager Plant December 2012