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 17 years and an estimated further 40 years underground and has been in production since November 2009.
Significant resource of 867.5 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.
The Tharisa Mine is underlain by the Middle Group (MG) and Upper Group (UG) Chromitite Layers. The MG Chromitite Layers outcrop on the property striking roughly east to west with a gentle change in strike to NW-SE in the far west. The layers dip at between 9° and 15° to the north. Towards the western extent of the outcrop, the dip is steeper. The stratigraphy typically narrows to the west and the dip steepens. The dip typically shallows out at depth across the extent of the mine area. The MG Chromitite Layer package consists of five groups of chromitite layers, being the MG0 Chromitite Layer at the bottom, followed by the MG1 Chromitite Layer, the MG2 Chromitite Layer (sub-divided into C, B and A chromitite layers), the MG3 Chromitite Layer and the MG4 Chromitite Layer (sub-divided into 4(0), 4 and 4A chromitite layers). The layers between the chromitite layers frequently include stringers or disseminations of chromite. The MG Chromitite Layers at the Tharisa Mine are a typical stack of tabular deposits.
The life of mine plan was designed to extract the MG Chromitite Layers, firstly from open pit mining to a maximum depth of 200 m and subsequently from underground extraction (MG2 and MG4 Chromitite Layers) by means of a bord and pillar mining method.
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 2034 before a transition to underground mining. 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.
Large scale open pit mining has traditionally been conducted by specialist mining contractors but in FY2017 Tharisa Minerals announced its plans to transition from contractor to an owner mining model. During that year, the Company acquired the mining fleet from the previous mining contractor and also acquired a drilling sub-contractor’s business to start in-sourcing the drilling operations and, as an owner operator, focus on improving ROM grades and fragmentation. In October 2017, approximately 900 former contract employees were transferred onto the mine.
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.
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.
During the year, the Group produced PGM concentrates containing 143.6 koz of contained PGMs (5PGE +Au) and chrome concentrates of 1.3 Mt. Of the chrome concentrates produced, 323.1 kt was specialty grade concentrates. Specialty chrome recovery circuits are integrated into the feed circuit of the Genesis Plant, known as the Challenger Plant. The Challenger Plant, which is owned by subsidiary Arxo Metals, was commissioned in July 2013 and produces chemical and foundry grade chrome concentrates.
The Voyager Plant chrome processing circuit was modified in FY2016 to increase chemical grade chrome production to diversify the product range from metallurgical grade with its Chinese and Asia-centric market to global markets, particularly taking the price differential between the products into account.
Production of specialty grade concentrates accounted for 24.3% of total chrome production in FY2017. Production of specialty grades will be maintained at current levels to ensure that it maintains a strategic market share.
Developing and optimising the Group's beneficiation capabilities.
Arxo Metals owns the Challenger Plant, which is integrated into Tharisa Minerals’ Genesis Plant. The Challenger Plant is dedicated to the production of specialty grade chrome concentrates, namely chemical and foundry grade concentrates.
Specialty grade concentrates carry more stringent specifications and therefore fetch a higher value. Arxo Metals has an off-take agreement with Rand York Minerals, which markets and sells the concentrates to customers in the chemical and foundry industries globally. Arxo Metals produced 65.7 kt of chemical grade chrome concentrate and 23.1 kt of foundry grade chrome concentrate in FY2017.
In August 2017, Arxo Metals entered into an agreement with Western Platinum, a subsidiary of Lonmin, on the operations of its K3 UG2 chrome plant and for the sales and marketing of the UG2 chrome concentrate produced. Arxo Metals will unlock greater value for Lonmin from the K3 UG2 chrome plant using innovative technology already in use at Tharisa’s operations. Adding approximately 200.0 kt to the Group chrome sales annually, the agency agreement expands the basket of chrome concentrates sold by the Group and leverages off its established logistics and marketing platform.
Arxo Metals is also the beneficiation, research and development arm of the Group. Arxo Metals conducts extensive research into technologies and downstream beneficiation opportunities that have the potential to improve yields and recoveries at the Tharisa Mine. The creation of increased value PGM and chrome products through the expansion and optimisation of the Group’s processing operations is its core focus.
During FY2017, Arxo Metals commissioned a 1 MW DC furnace to produce PGM-rich alloys on a pilot scale. This alloy will be smelted by Lonmin as part of a PGM research and development cooperation agreement. The production of PGM-rich alloys will further develop Tharisa’s beneficiation capability and thereby the profitability of Tharisa’s PGM segment.
Arxo Metals continues to evaluate low-capital, low-energy, value adding beneficiation projects through in-house research and in association with international companies.
Direct relationships with the Group's customers.
Arxo Resources has the exclusive right to sell the metallurgical grade chrome concentrate produced by Tharisa Minerals to customers in China and other international markets. It has established a strong platform with global customers.
Arxo Resources has a marketing agreement with Noble, a global commodities trading company listed on the Singapore Stock Exchange, whereby Noble acts as an agent for the marketing of 600.0 ktpa of metallurgical grade chrome concentrate produced by Tharisa Minerals. Arxo Resources also has a joint marketing agreement with Rand York Minerals for Tharisa Minerals’ chemical grade chrome concentrate production.
In FY2017, Arxo Resources sold 995.8 kt of Tharisa Minerals’ metallurgical grade chrome. The scale of Arxo Resources operations allows for direct access to market and price discovery. Its established contacts with customers also directly creates an excellent platform for additional sales of third party products.
Efficient in-house distribution of products to end customers.
Arxo Logistics provides an integrated logistics platform that reduces the risk and costs of transporting concentrates. It manages the road transportation of Tharisa’s PGM concentrates to Impala Platinum and the long-haul transportation of chrome concentrates from the Tharisa Mine and Lonmin’s K3 UG2 chrome plant to international customers through bulk and container vessels. Exports take place via the Richards Bay Dry Bulk Terminal and the Durban container port on the South African coast.
Arxo Logistics currently has the exclusive use of the Marikana railway siding for chrome exports. Negotiations regarding a planned public-private partnership for an on-site railway siding at Tharisa Mine are continuing.
Arxo Logistics shipped a total of 995.8 kt of chrome concentrate in FY2017 mostly to main ports in China. Of this, 98% was shipped in bulk with bulk shipments being preferred by customers due to ease of handling and reduced port charges, as well as reduced levels of administration.
The logistics arm of the Group has the necessary road and rail transport capacity, warehousing facilities and port facilities at the Richards Bay Dry Bulk Terminal and the Durban container port to manage Tharisa Mineral’s full production capacity. It also serves as a platform from which the Group can provide services to additional third party customers.
Arxo Logistics provided third party logistics services during the period under review and is planning to expand this service offering in the year ahead.