The two-billion-year-old Bushveld Complex is the largest layered igneous complex in the world, and is the repository for around 85% of known global PGM resources.

The magmatic layering in the RLS is laterally persistent and can be correlated throughout most of the complex. Layering is generally shallow dipping towards the centre of the complex. The RLS stratigraphy is sub-divided into five zones, which are, from lowest to highest, the marginal zone, the lower zone, the critical zone (which is further subdivided into a lower and upper unit), the main zone and the upper zone.

The Booysendal mining concession is located in the southern compartment of the eastern limb of the Bushveld Complex

The Bushveld sequence at Booysendal is similar to that found across the southern compartment of the eastern limb. The critical zone stratigraphy is fully developed, and middling between the UG2 and Merensky reefs is in the order of 175m in the northern and central portions of Booysendal. The sequence is, however, subject to thinning in the far southern portion, which is linked to the Bushveld rocks abutting basement highs. The impact of this ‘abutment’ is further manifested in localised zones of disruption to surface morphology and internal structure of the two reefs. This has led to the characterisation of three geozones within the Booysendal concession, these being the normal, slump and abutment geozones. Despite this progressive disruption to the south, the continuity of the reef surfaces is robust across the property.

The Booysendal mine contain resources of both the UG2 and Merensky reefs.

The UG2 reef consists of an upper leader chromitite and a lower main chromitite with a combined thickness of some 140cm. These seams are generally juxtaposed or merged, but can display variable internal silicate partings.

The Merensky reef is the upper mineralised portion of the Merensky pyroxenite, generally extending over 110cm. The Merensky reef is immediately overlain by a sequence of competent norites.

The relatively large vertical separation of the reefs leads to separate districts for the UG2 and Merensky mining, accessed via separate development tunnels. The Booysendal North and South mines are underground, mechanised bord and pillar mines, accessed from surface via ramp decline systems.

The North UG2 mine decline system comprises three declines on the plane of reef and one decline situated 20 m into the footwall of the reef, containing a belt for ore handling. This footwall belt decline extends 1 300 m in the down dip direction from the outcrop, after which all decline development is on the plane of reef. An ore silo decouples the footwall and on-reef belt systems. Decline systems for the South UG2 mines comprise four declines on the plane of reef.

Mining sections extend over a dip length of 144 m, equating to a vertical interval of 25 m. Strike drives are inclined at 5° above the line of strike. Mechanised boom rigs and LHDs are employed in mining and development. Strike belts within the drives transport ore to the central decline dip belt system for hoisting to surface. From there, transport to the respective concentrator plant is via terrestrial or aerial rope conveyor belts (Ropecon) or trucking.

Concentrating: Merensky and UG2 plants
• In the crushing/screening circuit, the ore is crushed to reduce its size before it goes to the mill
• Merensky ore feeds into a fully autogenous mill. In the UG2 plant, the ore feeds into a high pressure grinding roll crusher and then into a primary ball mill

The Booysendal North mine comprises a UG2 and Merensky module. A unique reverse decline at North UG2 mine connects the concentrator plant and other mine infrastructure situated on a plateau with the on-reef declines that access the underground mine and outcrop on the side of the valley. This design has helped to minimise the mine footprint.[2019 AR, p. 64]

There is one 200 000tpm PGM concentrator plant on surface at the North mine, along with a dense media separation plant and a chrome spiral plant. [2019 AR, p. 64]

The South mine has a 250 000tpm PGM concentrator, with a chrome spiral plant and associated tailings facilities, as well as normal mining infrastructure such as offices, workshops, stores and access to underground workings. Booysendal South concentrator was commissioned in April 2019. [2019 AR, p. 51, 64]

Concentrating: Merensky and UG2 plants
• In the crushing/screening circuit, the ore is crushed to reduce its size before it goes to t ........