Overview

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 ore bodies 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 exploited reef, accounting for 51% of ore mined at Kloof, while the KR, MVR, and LR account for 29%, 17% and 3%, respectively.

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

• Truck & Shovel / Loader
• Scattered stoping
• Breast mining

Summary:

Kloof is a large, established intermediate to ulira-deep level goid mine that is accessed from surface through several shaff systems to 40 Level (currently the deepest working level), some 3,200m below surface. Kioof comprises three producing shaff systems fhat mine different coniributions from pillars and open ground.

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
There is one active TSF, the Leeudoorn TSF, which has a capacity of 38.8Mt and is fed to the Kloof No. 2 plant. The LoM requirements for this TSF is only 0.7Mt, resulting in a surplus capacity of 38.1Mt. The remainder of the tailings will be deposited on the Driefontein TSFs as the bulk of the Kloof material will be processed at the Driefontein No. 1 Plant post 2024.

Key developments and brownfield projects
The long-term decline in productivity at No. 4 shaft, including the the impact of seismicity and loss of mineable face length, was compounded by a significant shaft incident in 2023 and has resulted in early shaft closure and the removal of all Mineral Resources and Mineral Reserves below 41 level. This accounts for the bulk of the changes year-on-year to both the Mineral Resource and the Mineral Reserve at Kloof

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 has allowed for the phased closure of No. 3 shaft’s sub-vertical shaft, with the final closure of the main shaft-barrel planned for 2024. The final phase, which is in execution, 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, including the MVR, the KR and the LR. Secondary reefs represent additional goldbearing formations within the mine beyond the primary reef structures. 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.

Comminution

Crushers and Mills

Summary:

Reef is trucked and conveyed to a central stacker pad which feeds two SAG mills equipped with variable speed ring motor drives. The two SAG mills can be operated as fully autogenous units, or as currently being operated, as semi-autogenous units by adding steel grinding balls.

Processing

• Calcining
• Smelting
• Crush & Screen plant
• Agitated tank (VAT) leaching
• Carbon in pulp (CIP)
• AARL elution
• Carbon adsorption-desorption-recovery (ADR)
• Solvent Extraction & Electrowinning
• Cyanide (reagent)
• Rotary kiln & Electric furnace

Summary:

Kloof has only No. 2 Plant operating and is situated at No. 7 Shaft with No.1 plant having closed in December 2022.

The No. 2 Plant has a long operational history. The current operational capacity of Kloof No. 2 Plant is 167t per month. The underground feed sources are the Main Shaft, No. 7 Shaft and No. 8 Shaft. The plant is considered to be both mechanically and structurally in good condition. No 2 plant is scheduled for closure in July 2024. There after all ore will be trucked to the plant at the neighbouring Driefontein mine for Processing.

Kloof is currently sending surface material to neighbouring operations Driefontein No. 1 Plant and Ezulwini Plant on a toll-treatment basis. The SRDs at the operation have been mined since the early 2000's and has resulted in a significant reduction in the environmental liability of the operation. All SRDs are extensively sampled and screened prior to milling. Surface material can be treated as a top-up fo underground material af No. 2 Plant and has been done in the past.

Kloof has access to all material requirements through local suppliers or international suppliers.

Milled ore is thickened ahead of cyanide leaching in air-agitated tanks and adsorption onto activated carbon ina conventional CIP circuit. Loaded carbon is eluted in an AARL elution circuit, which was upgraded in June 2001 and further in October 2003, and now serves as the central elution facility for Kloof. The upgrade included the installation of Continuous Electro-winning Sludge Reactors which are working very efficiently. Cathode sludge is filtered and smelted to produce doré.

The underground tonnages sent to the mill include waste development tonnages which are hoisted and trammed separately at the shaft and then sent through to the mill. The inclusion of these development tonnages exceeds the current plant capacity. The waste development will therefore be stockpiled at the plant and used to supplement the underground feed as required. The waste development has been planned at 0.0 g/t but in reality, has been shown to contain approximately 0.5 g/t and compliments the MCF when milled due to the occurrence of uncalled footwall bands.

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

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.

Sibanye-Stillwater recognises waier as a critical resource. The Company further considers its integrated approach to the management of the water foofprint and the waier systems infrasiructure 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.

Production

Operational metrics

Personnel

Job Title	Name	Profile	Ref. Date
Environmental Manager	Bashan Govender		Aug 5, 2024
Mine Planning Manager	Steven Wild		Aug 5, 2024
VP Operations	Moses Netshivhazwaulu		Aug 5, 2024
VP, Technical Services	Charl Labuschagne		Aug 5, 2024