Summary

Deposit type

• Paleoplacer

Summary:

Kloof is located along the West Wits Line that forms part of the Far West Rand of the Witwatersrand Basin. The Witwatersrand Basin comprises a 6,000m vertical thickness of sedimentary rocks, extending laterally for some 350km northeast to southwest by some 120km northwest to southeast, generally dipping at shallow angles toward the centre of the Witwatersrand Basin. The Witwatersrand Basin outcrops at its northern extent near Johannesburg, but to the west, south and east it is overlaid by up to 4,000m of volcanic and sedimentary rocks.

Gold mineralisation occurs within laterally extensive quartz-pebble conglomerates called reefs, which are developed above unconformable surfaces. As a result of faulting and primary controls on mineralisation processes, the goldfields are not continuous and are characterised by the presence or dominance of different reef units. The reefs are generally less than two metres thick and are widely considered to represent laterally extensive braided fluvial deposits or unconfined flow deposits, which formed along the flanks of alluvial fan systems around the edge of an inland sea. Dykes and sills of dolerite composition are developed within the Witwatersrand Basin and are associated with several intrusive and extrusive events.

Gold generally occurs in native form, often associated with pyrite, carbon and uranium. Pyrite and gold within the reefs display a variety of forms, some obviously indicative of detrital transport within the depositional system and others suggesting crystallisation within the reef itself.

The Kloof orebodies comprise four gold-bearing reefs, namely the Ventersdorp contact reef (VCR), the Middelvlei reef (MVR), the Kloof reef (KR), and the Libanon reef (LR). The VCR, located at the top of the Central Rand Group, is the main historically exploited reef, but currently accounts for only 44% of ore mined at Kloof, while the KR, MVR, and LR account for 38%, 17% and 1%, respectively. This shift away from the VCR is partly due to the depletion of the VCR, but also accelerated by the recent closure of Kloof 4 shaft.

The average dip of the reefs is 25 to 35 degrees to the south-east and the strike is approximately north-east south-west. The reefs are generally less than two metres thick.

Kloof Reef
The Kloof Reef zone is situated some 50m to 70m above the Libanon Reef and it is exploited at Main Shaft, No. 7 Shaft and No. 8 Shaft. It comprises of several conglomerate bands and interbedded quarizites. The base of the zone is marked by a thin grit to small pebble conglomerate, called the Footwall Marker, overlain by coarse-grained light green to grey quarizite.

The economic Kloof Reef is known as the KRS1I, and when payable it comprises robust large pebble conglomerates, generally oligomictic, but with polymictic upper bands common.

Above the reef, an argillaceous quarizite is present and varies from a few centimetres thick to less than 2m. This quartzite is often “blocky” due to the many bedding planes. An argillite marker or argillite parting can often be noted in this zone.

Above the argillite marker is a conglomerate (or occasionally a pair of conglomerates) known as the KRS2. These are small fo medium pebble conglomeraies usually oligomictic with generally sub-angular small whife and smoky quartz clasts. if is often well mineralised and carries gold. Faulting in stopes often exposes this band.

Eight facies types are recognised for the Kloof Reef.

Libanon Reef
Situated approximately 70m below the Kloof Reef, and on top of the Booysens shale is the Libanon Reef. This was mined locally at Kloof No. 3 Shaft and No. 8 Shaft, but due to variability in grade, it is a minor component of the Kloof Mineral Resources. With the opening of old cross cuts underway in the upper levels of Main Shaft and the expansion at K8, Libanon Reef exposures should become available to enable a detailed geological study of this reef horizon.

Five facies types have been identified for the Libanon Reef. Extension of fhe Libanon Reef unknown facies is a result of sampling data from crosscut and stope sampling at No. 7 Shaft.

Middeiviei Reef
The Middelviei Reef zone occurs approximately 60m above the Green Bar and is mined extensively at No. 1 SV Shaft. The reef zone consists of a sequence of conglomerates, quarizites, and pebbly quarizite. The bottom band Is split into an upper and lower cycle with the upper cycle being erosive, and where channelised it becomes the primary gold carrier. The delineation of these upper-cycle channels, both upstream and downstream, is an important aspect in exploration targeting.

Eight facies types have been recognised for the Middelviei Reef.

Mining Methods

• Scattered stoping
• Breast mining

Summary:

The Kloof operation is a mature, established mine, making use of conventional breast mining techniques. The Kloof operation consists of three producing vertical shafts, namely No.1 shaft, No. 7 shaft and No. 8 shaft. 40 Level is currently the deepest working level at No. 7 shaft, approximately 3,200m below surface.

During 2023, Kloof 4 shaft was closed due to economic and safety considerations.

Mining Methods
The orebody is narrow tabular in nature and is accessed through vertical shafts, with evenly spaced development in the footwall. On reef development is advanced on true dip, with conventional finger or wide raises and then stoped to either side in the direction of strike. All mining at Kloof is conventional in nature and is consistent with other similar orebodies.

Mining methods are based on a number of factors and are shaft, infrastructure and orebody specific. They are made by experienced mining engineering professionals, with input from all disciplines.

The mining methods employed at Kloof are subdivided as follows:
- The predominant mining layout at Kloof is scattered grid with breast stoping and dip pillars.
- Scatterred mining of white blocks (previously left unmined).
- Mining of blocks previously left as pillars is mostly up-dip.
- Standard dimensions for the mine planning block is 150m spans with 30 m dip pillars.
- Interlevel spacing is 70-80m.

No backfill operations are conducted. No stripping is required as operations are accessed through underground development and surface sources are readily available.

All mining, specifically from white areas, undergoes a continual risk assessment process and those areas that currently pose a risk are excluded from the Mineral Reserves.

Mineral Reserves generation is done through the development of footwall drives (approximately 90m in the footwall) and crosscuts to reef. Crosscut spacing is based on a selective grid (100m fo 180m apart), depending on evaluation, rock engineering principles and structure.

Finger-raise development with breast ledging is done on the secondary reefs and in selected areas on the VCR where the hangingwall consists of Alberton lava. The majority of the VCR mining at all shafts makes use of wide raising, with the hangingwall consisting of Westonaria Formation lava (WAF), to ensure the excavation is properly de-stressed during development.

Underground development is extensive, as can be expected of a mature mine of this size. Underground infrastructure includes access infrastructure (to convey personnel, materials and equipment to and from the working areas) and associated services to support mining operations. Horizontal infrastructure includes crosscuts, return airway drives, footwall haulage levels, and declines/inclines. Infrastructure required for ore flow and services include ore and waste passes, conveyor belts, battery-powered rail conveyances, ore bins, loading stations, water dams, dewatering pump stations, secondary ventilation and workshops. Electrical, compressed air, and water reticulation are also part of the installed underground infrastructure.

Tailings deposition and capacity
Tailings will be deposited on the Driefontein TSFs as the Kloof material is being processed at the Driefontein No. 1 Plant.

Key developments and brownfield projects
The Kloof integration project, which aims to optimise and rationalise the infrastructure between The Kloof integration project, which aims to optimise and rationalise the infrastructure between No. 1 shaft and No. 3 shaft, is continuing as planned. This optimisation entails the re-opening of old development areas between No. 1 shaft and No. 3 shaft, which will allow the mining of the remaining VCR and other secondary reefs at No. 3 shaft, from No. 1 shaft.

The Kloof operation has several secondary reefs (orebodies), including the MVR, the KR and the LR. Secondary reefs represent additional gold-bearing formations within the mine beyond the primary reef (the VCR). These secondary reefs can contain economically viable concentrations of gold and are targeted for exploration and extraction to extend the lifespan of the mine and increase overall productivity. Studies are underway to identify and test new mining methods, specifically targeting these large secondary reef areas, to secure a stable base which can then be enhanced with the addition of some of the higher grade remaining VCR areas.

Comminution

Crushers and Mills

Summary:

Driefontein No.1 Plant
The milling circuit consists of two 250 tonne per hour refurbished SAG mills. Each milling circuit is closed with a cyclone cluster comprising 6 inclined cyclones (3 operational, 3 standby). The ore is ground to a final product size of 80% finer than 75 microns and the pulp overflows to the thickeners section through a linear screen (to remove woodchips or any debris).

Processing

• Smelting
• Crush & Screen plant
• Carbon re-activation kiln
• Agitated tank (VAT) leaching
• Carbon in pulp (CIP)
• Carbon adsorption-desorption-recovery (ADR)
• Elution
• Solvent Extraction & Electrowinning
• Cyanide (reagent)

Summary:

The Kloof 2 plant was closed in 2024. Fresh ore is transported by road to the Driefontein No. 1 plant, approximately 20km to the west of the Kloof Operation, as part of infrastructure optimisation. In addition, selected Kloof surface rock dump (SRD) material is treated at the Ezulwini processing plant.

Driefontein No. 1 Plant
The drum filtration and zinc precipitation sections were replaced by a carbon in pulp ("CIP"), elution and carbon regeneration facility in August 2001. In September 2003, two single stage SAG mills operating in closed circuit with hydrocyclones replaced the conventional crushing and milling circuits. Cyclone overflow is screened to remove trash ahead of the two high-rate thickeners, air agitated leaching and Kemix Pump Cell CIP adsorption.

Loaded carbon is transferred to the centralised elution facility located at No.1 Plant for acid treatment, Zadra elution and electrowinning. Eluted carbon is thermally regenerated and returned to the adsorption circuit. Gold bearing cathode sludge is recovered by washing, filtration, drying and smelting to produce doré. 90% of the Tailings from the Pump Cell circuit are either wholly pumped directly to two Tailings Storage Facilities ("TSFs"), and the remaining or 10% of the residue material is cycloned and pumped underground as backfill. Water recovered from the TSFS is recycled back to the No.1 Plant for use as process water.

The capacity of No.1 Plant is 240ktpm but is planned to operate with only one mill over the LoM and is reduced to 120ktpm.

The comminution and adsorption circuits are relatively new, and the balance of the plant is mechanically and structurally sound. With adequate ongoing maintenance No.1 Plant should readily meet LoM requirements.

Final Product
Doré gold, an unrefined alloy of gold with variable quantities of other base and precious metals, is produced before being sent for refining to Rand Refinery Limited.

Water Supply

Summary:

Gold mines are dependent on water fo sustain operations. Kioof receives water from two main water sources:
- excess underground fissure water
- potable water is purchased from the Rand Water Board network, which draws water from the Vaal River System.

The potable water treatment technologies include:
• Kloof Phase 1 - reverse osmosis system
• Kloof Phase 2 - zero-liquid discharge fluidised bed cold-lime softening plant, combined with a Nickel/Uranium specific Ion exchange system.

Sibanye-Stillwater recognises water as a critical resource. The Company further considers its integrated approach to the management of the water footprint and the water systems infrastructure as a key component of its business strategy.

Water is used for:
- processing and transportation of ore material
- cooling and humidification of ventilation air for underground mining
- underground mining activities such as drilling
- cooling of equipment
- chemical make-up dosing
- consumption and sanitation
- irrigation.

The water system is operated such that water is recycled and re-used wherever possible.

Excess fissure water is extracted and discharged under license conditions as described above. Mine water is recycled and re-used where possible. The separation of mine water and fissure water is a key focus area to prevent the contamination of fissure water by the mining processes.

Sibanye-Stillwater has various projects to leverage excess ground water and reduce dependence on external suppliers. There is a 4ML/day water treatment facility (based on a build-own-operate transfer model) at the Kloof operations. The plant met 28% of Kloof’s potable water demand, reducing the company’s reliance on external suppliers significantly.

Pipelines exist for various uses throughout the mine, underground and on the surface, mainly for water and compressed air for mining. The process plant pipeline infrastructure includes that used for tailings deposition. No additional pipelines will be required for the LoM.

The Group approved capital expenditure for the construction of a pilot plant for the recycling of ~ 1.3 ML/day wastewater from our wastewater treatment works at Kloof. Designs were approved and orders placed for the manufacturing and delivery of equipment for the pilot plant.

Commodity Production

Operational metrics

Personnel

Job Title	Name	Profile	Ref. Date
Environmental Manager	Bashan Govender		May 2, 2025
Mine Planning Manager	Steven Wild		May 2, 2025
VP, Technical Services	Charl Labuschagne		May 6, 2025