Regionally, Grootegeluk is in the southern portion of the Limpopo depression, a relatively small corridor between the Limpopo River in the west and the Palala-Pietersburg plateau in the east. Fundamentally, it is a re-exposed post-Waterberg topographical feature on which Karoo sediments were deposited, followed by tectonic activity, which was the primary element responsible for the development of the depression.

The Zoetfontein fault forms the boundary of the Waterberg coalfield in the north while the Eenzaamheid fault forms the boundary in the south. The Daarby fault, with a throw of some 350m, divides the coalfield into a deep north-eastern portion and a shallow south-western portion. The first fresh coal in the shallow south-western portion is on average 20m below surface. The lowermost coal seam (zone 1) occurs at a depth of about 130m in the shallow portion of the coalfield but this may vary depending on the local structure (Figure 16). The predominantly horizontal coal-bearing formations have a very gentle dip to the south-east near Grootegeluk. Only a few dolerite dykes outcrop in the south-eastern portion of the Waterberg coalfield and no sills have been encountered in any exploration boreholes drilled in the mine right area to date.

The upper part of the coal deposit, the Volksrust formation (±60m thick), comprises intercalated mudstone or carbonaceous shale and bright coal layers. It displays such a well-developed repetition of coal-shale assemblages that it can be subdivided into seven discrete sedimentary cycles or zones (zone 11 – zone 5). Smaller subcycles (samples) were chosen within these zones and sampled individually in the exploration phase. This subdivision of coal seams into smaller lithological units is necessary to cater for numerous mining bench definitions and/or product specifications. The terms “zone” and “sample” are used at Grootegeluk instead of “seam” and “ply” due to the site-specific intercalated nature of the coal and shale. The Volksrust formation is classified as a thick interbedded seam deposit type.

The Volksrust formation zones typically start with bright coal at the base. The ratio of coal to shale decreases from the base of each zone upwards. The basal zone (zone 5) is an exception because of a more homogeneous distribution of coal and shale throughout this zone. The Volksrust formation shale shows an increase in carbon content with depth and varies from a massive bluish- grey mudstone to carbonaceous shale towards the base. Although the thickness and coal quality of the Volksrust formation are reasonably constant across the coal field, a large variation in the yield of semi-soft coking coal and total sulphur content occurs vertically in the coal succession.

The Vryheid formation (±55m thick) forms the lower part of the coal deposit and comprises carbonaceous shale and sandstone with interbedded dull coal seams varying in thickness from 1.5m to 9m. It is therefore classified as a multiple-seam deposit type.

There are five coal zones that consist of predominantly dull coal with some bright coal developed at the base of zones 2, 3 and 4 in the Vryheid formation. Due to lateral facies changes and variations in the depositional environment, these zones are characterised by a large variation in thickness and quality. It is noted in the mine lease area that these zones depreciate in development and coal quality in a westward direction due to sedimentological facies changes. Zone 3 is the best-developed dull coal zone in the mine lease area and reaches a maximum thickness of 8.9m. The basal portion of this zone yields some semi-soft coking coal. Zone 2, on average 4m thick, reaches a maximum thickness of 6m in the mine lease area. The basal portion of this zone also exhibits semi-soft coking coal properties. Zone 2 exhibits the most consistent thickness of all the Vryheid coal zones across the entire Waterberg coalfield. Zone 1, the basal Vryheid coal zone, has an average thickness of 1.38m. Zone 1 contains the best-quality metallurgical coal at Grootegeluk and is suitable to produce char but is not included in the mine plan due to the high stripping ratio given a 12m thick overlying interburden sandstone seam. Due to previous mining activity, over 5Mt of high-quality low- phosphorous content metallurgical coal from zone 1 has been sterilised to date by the pit backfill operation.

The Grootegeluk surface coal-mining operation consists of a series of parallel benches advancing progressively across the deposit via a process of drilling, blasting, loading and hauling with truck and shovel fleets. The mining bench definitions in the Vryheid and overlying Volksrust formations coincide with the geological boundaries, resulting in 14 mining benches for saleable products and waste.

Geological challenges, as already noted in 2018, are increasing as the mine advances to the west. The upper top benches are thinning and will eventually discontinue due to weathering with only a small portion of bench 2 remaining in the next few years. Weathering is highly irregular, specifically in faulted areas, and impacts mining as well as disrupting downstream beneficiation plant throughput. An increase in faulting, in offset and frequency, is observed within but also to the south and north of the current pit. For the first time, a fault-defined graben structure was encountered within the pit, which presents a risk to the execution of the short-term mine plan and for the routing of the correct RoM to the appropriate coal-handling facilities. Continuous pit mapping, downhole geophysical surveys of all holes, including blast holes, as well as close-spaced infill drilling are employed to target these geological challenges. This high-resolution information enabled the operational team to proactively plan and largely mitigate the geological challenges. During 2019, a significant number of openholes were also drilled, roughly 100m apart and positioned on 250m-spaced north-south profile lines in front of the advancing pit. The aim of the holes was to intersect the overburden as well as the full succession of the Vryheid (multi-seam) and Volksrust (thick-interbedded) coal formations to supplement the existing exploration information. The results delivered significant value regarding overburden characterisation and increased the level of confidence of the geological structures, and the accuracy of our bench/seam definitions in the two formations. The profile drilling will continue in 2020 and beyond, based on the success of the results achieved.

The geological model of Grootegeluk is updated every second year, and information from drilling campaigns in 2017/2018 was included in a geological model update, which is currently being used for the review of the Grootegeluk exploitation strategy. The strategy is considering several potential optimisation scenarios, including a review of the current pit turnaround and backfill strategies as well as the bench definitions to optimise bench height for floor control and decreasing mining losses. The Grootegeluk integrated water use management strategy is progressing well in addressing all water-related aspects to provide a strategy for the optimal use of water throughout the value chain. This project will integrate with the exploitation strategy and is expected to enhance water use and water accumulation within the pit significantly. A study initiated in 2018 to review mining of the significant amount of overburden is in progress. The project investigated a number of options to replace the existing load-and-haul mining method with a more cost-effective alternative by considering mining and transporting overburden material via a bulk-materials handling system. The prefeasibility study is still under way to identify the preferred alternative.

Exxaro is proposing to expand their existing mining operations by extending the opencast mining operation to the farm Turfvlakte 463 LQ. The farm is located within the existing Grootegeluk Coal Mine’s Mining Right, LP 46 MRC. The opencast operations will consist of two pits, namely Pit 1 and Pit 2. Pit 1 will be 158 ha in size and will be 88 m deep, while Pit 2 will be 64 ha and 109 m deep. [2020, TR, p.34]

Sufficient coal reserves have been proven to support opencast mining. Due to faulting in the area, Benches 9A and B and Bench 11 will be at quite shallow depths and high-quality coal can be mined at a favourable stripping ratio. [2020, TR, p.34]

Grootegeluk Coal Mine is considering two options for the mining of Pit 1 and Pit 2. The preferred option is to mine Pit 1 and then Pit 2 to produce 1.5 million tonnes per annum run of mine (ROM) coal over a period of twelve (12) years. [2020, TR, p.34]

Pit 1
Pit 1 will be mined to a depth of about 88 meters. Mining will commence in the northern part of the proposed pit and progress towards the south. [2020, TR, p.103]

Pit 2
Pit 2 will be mined to a depth of about 109 meters. Mining will commence in the north-eastern part of the proposed pit and progress towards the north-west. [2020, TR, p.103]

The location of the exterior haul roads and associated infrastructure are dictated by the perimeters of the final open pits. A topsoil stockpile will be constructed between the perimeter of the open pits and adjacent public roads, where possible. [2020, TR, p.103]

Coal is beneficiated via eight different plants that produce power-station coal (thermal coal) at 35% ash, variously sized metallurgical coal products at different quality specifications and semi-soft coking coal. Thermal coal is sold to Eskom in terms of long-term coal-supply agreements to supply feed coal to the Matimba and Medupi power stations via conveyor belts. Variously sized metallurgical coal products at 15% ash and 11.25% ash, semi-soft coking coal at 10.3% ash, as well as steam coal at 12.5% ash are railed to various customers and shipped to international clients via an export harbour. A small portion of the total product is sold on- site to smaller customers and dispatched by road.