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 Complex stratigraphic sequence at Booysendal is similar to that found across the southern compartment of the eastern limb. The Critical Zone stratigraphy is fully developed. The middling between the UG2 and Merensky Reefs is in the order of 175 m in the northern and central portions of the property. The sequence is, however, subject to thinning in the far southern portion, which is linked to the RLS strata abutting onto a basement high. 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 site, these being the Normal, Slump and Abutment geozones. Despite this progressive disruption to the south, the reef surfaces are interpreted to be continuous across the property.

The internal structure of the UG2 Reef is similar to that found on the western limb, whereas the Merensky Reef is typical of the thick pyroxenite-type unit of the northern portion of the eastern limb as well as that of the south-eastern portion of the western limb.

Merensky Reef
The Merensky Reef rests in the upper mineralised portion of the Merensky pyroxenite unit, generally extending over 110 cm. It is immediately overlain by a sequence of competent, norite bearing strata. A stringer chromitite layer may be present approximately 10 cm below the top of the Merensky pyroxenite. PGM and base metal mineralisation is uni-modal, generally with highest concentrations occurring just below the elevation of the stringer chromitite, tailing off rapidly into the overlying norite and more gradually into the underlying pyroxenite. In the absence of the stringer chromitite, the grade peak amplitude is generally reduced and the stratigraphic extent of appreciable mineralisation extended.

UG2 Reef
The UG2 Reef consists of the upper Leader and lower Main chromitite layers with a combined average thickness of approximately 1.4 m. These seams are generally juxtaposed or merged, but can display variable internal silicate partings. Overlying this is a pyroxenite of variable thickness, up to 3.5 m, containing up to five narrow chromitite layers. The middling between these narrow layers and the top of the Leader chromitite gradually increases towards the west.

Geological Discounts
Geological losses were discounted from the Mineral Resources for both reefs. There is no change in estimated losses from 2019. Within the mining blocks, there is higher degree of geological confidence on the losses due to closer spaced drilling and mining exposure. Geological losses are circa 13% and 17% for the UG2 and Merensky Reefs, respectively.

The geological losses for the Booysendal prospect, comprising pothole and structural features, are estimated to range between 24% and 32% loss for the UG2, and between 22% and 26% loss for the Merensky Reef. Additional geological losses for the Booysendal prospect are applied as a contingency where drilling is sparse.

Booysendal consist of two Mining Rights (MR), namely the Booysendal North MR and the Booysendal South MR (old Everest mine). These MR are managed as one operation divided into five operational areas. Booysendal North (the existing mining operation), BCM1, BCM2 and BS1/2 (all four of these areas are located on the Booysendal North MR), while the Valley Boxcut and the existing Everest mine (BS4) is located on the Booysendal South Mining Right.

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.

North UG2 mine is planned, with a current remaining life of more than 20 years, to produce 2.4 Mt of ore per annum at steady state, generating in the order of 185 000 oz of 4E metals in concentrate, together with associated precious and base metal by-products.

The two initial UG2 mining modules of South mine have estimated lives of greater than 20 years at a combined steady state production rate of 2.5 Mt of ore per year, generating circa 200 000 oz of 4E metals in concentrate, together with associated precious and base metal by-products.

A Ropecon is used to transport ore from the two South mine modules from the portals in the valley to the Booysendal South concentrator, located 4.8 km away on higher topography. This ore transportation system was carefully chosen to unlock the orebody potential in an environmentally sensitive area with efficiency, safety and lower cost. A second Ropecon is currently being constructed between North and South mines. This will allow overspill production from North mine to be transported to the South concentrator.

The North & South Merensky mines are essentially analogs of the South UG2 mine, with all development on reef. The phase 1 North Merensky mine is producing at steady state of 0.3 Mt of ore per annum generating in the order of 25 000 oz of 4E metals in concentrate, together with associated precious and base metal by-products. North Merensky mine will be ramped up to 0.65 Mt per annum upon commissioning of the second Ropecon. The South Merensky mine is planned to produce, initially at 0.3 Mt of ore per annum, producing some 20 000 oz of 4E metals in concentrate, ultimately growing to 0.65 Mt per annum and 45 000 oz of 4E metals in concentrate.

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 ........