Two reef types are mined at the Rustenburg operations: UG2 Reef and Merensky Reef, both dipping at ~9° towards the northeast. The UG2 Reef consists of a main chromitite seam with an average thickness of 70cm. The mining cut includes the main seam and various components of hangingwall and footwall to a planned mining width varying from 105cm (conventional) to 120cm (mechanised).

The Merensky Reef lies 140m above the UG2 Reef and consists of pegmatoidal feldsphatic pyroxenite, with thin top and bottom contact chrome stringers, and has an average width of 20cm.The mining cut includes the Merensky Reef and various components of hangingwall and footwall to a planned minimum width varying between 105cm and 120cm.

Within the Rustenburg operation, the UG2 Reef occurs vertically between 90m and 150m below the Merensky Reef and dips in a north-easterly direction at about 9º to 12º. The UG2 Reef is more prone to undulations when compared to the Merensky Reef, resulting in rolling reef. [2020 Mr, p.63]

Both the UG2 and Merensky mineralisation occurs as tabular orebodies, and are laterally continuous with relatively long-range grade consistency and predictability.

Reef disruptions in the form of potholing, faulting, IRUP and dykes occur throughout the orebody resulting in an average geological loss of 15%.

Rustenburg consists of three intermediate depth operating vertical shafts, which utilise a conventional mining method (Siphumelele 1, Khuseleka 1 and Thembelani 1) and Bathopele, which is a shallow mechanised operation.

The Mineral Resource is accessed from surface using conventional underground mining methods to 34 Level (the lowest working level) at Siphumelele 1 Shaft, approximately 1,350m below surface, to 28 Level (the lowest working level) at Khuseleka 1 Shaft, approximately 950m below surface, and 29 Level (the lowest working level) at Thembelani 1 Shaft. The Mineral Resource at Bathopele Shaft is accessed from surface via two decline clusters using mechanised mining methods to a depth of approximately 500m below surface. 66% or 54.55Moz of the total Mineral Resources are above infrastructure and 34% or 27.78Moz are below infrastructure.

The vertical shafts target both the Merensky Reef and UG2 Reef horizons, whilst the shallow, mechanised Bathopele targets only the UG2 Reef.

Mining method:
• Vertical shafts: conventional scattered breast mining;
• Mechanised declines: bord and pillar.

Apart from the underground operations, there are also two tailings retreatment operations:
• WLTRP treats tailings from the old Waterval and Klipfontein TSFs, via hydro mining;
• Tails from the Waterval TSFs and Waterval UG2 and Retrofit concentrators are retreated at the Platinum Mile plant.

At Siphumelele 1 Shaft, a study has been initiated to replace the dwindling Merensky Reef Mineral Reserves, which is mined via a decline shaft system, extending below the lowest level (29 Level) of the vertical shaft system. The Siphumelele UG2 orebody, which is targeted in this project, will be accessed via the primary vertical shaft. The target area will be down-dip of the Kroondal mechanised Bambanani, Simunye and Kopaneng shafts, and extend between the existing 21 and 29 Levels. The Eastern limit is defined by the Siphumelele 2 Shaft boundary and the Western limit by the boundaries of Khomanani 1 Shaft and Thembelani 1 Shaft.

The underground ore is treated at the Waterval UG2 and Waterval Retrofit concentrators, after which it is subject to a smelting and refining agreement with the Rustenburg section of Anglo American Platinum. The Waterval UG2 concentrator has an integrated chrome recovery circuit, which recovers a chrome concentrate from the UG2 ore.

Treatment of the ore, comprising crushing, ball milling, gravity concentration and flotation is carried out in two reduction plants, an older unit and a more modern mill erected in the last few years, while a third mill is now in course of construction to handle the increased output.

The ore is first crushed in a series of jaw crushers and fed to the primary and then the secondary ball mills which are in closed circuit with hydrocyclone classifiers. This is followed by gravity concentration on corduroy tables to separate the course particles of platinum-bearing minerals and the free metallic particles.

The tailings from the ........