South Africa

Middelburg Mines Services (MMS) Mine

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Mine TypeOpen Pit
  • Coal (thermal)
Mining Method
  • Dragline
  • Truck & Shovel / Loader
Production Start... Lock
Mine Life... Lock
SnapshotMiddelburg Mining Services (MMS) (formerly the Wolwekrans and Ifalethu Mines) comprises two open-cast mining operations Middelburg North and Middelburg South.
Related AssetSeriti Power (SAEC) Operation


Seriti Resources Holdings Proprietary Ltd. 90 % Indirect
Johannesburg, 1 June 2021: Following the fulfilment on 15 May 2021 of all conditions precedent in respect of Seriti’s acquisition of South32 SA Coal Holdings Proprietary Limited (SAEC), Seriti is pleased to advise that the transaction has now closed and that it has assumed management of these operations from 1 June 2021.

SAEC has been renamed Seriti Power, and comprises the Khutala, Klipspruit, and Middelburg Mines Services (MMS) North and South mines, which provide coal to the Kendal and Duhva power stations, as well as export coal via the Richards Bay Coal Terminal. Seriti holds a 90% interest in Seriti Power, while an Employee Trust and Community Trust each hold a 5% interest.

Deposit type

  • Sedimentary


In the Wolvekrans area, sandstone filled fluvial channels are prominent below the No.5 Seam through to the No.2 Seam. In the Douglas area, a prominent fluvial sandstone channel is developed between No.2 Seam and No.2A Seam. Running in a north south direction it has affected the remaining No.2 Seam resource in the Douglas mining area. The No.2 Seam is generally thinner along the channel and intra-seam partings affect coal quality in the channel-affected area.

Coal seams at Wolvekrans-Middelburg Complex (WMC) are associated with glacio-fluvial and upper deltaic plain sedimentation. The main seams of economic importance include the No.4L, No.2 and No.1 Seams, which are generally thick and laterally continuous.

No.5 Seam (0 to 2 m) is the uppermost seam and is discontinuous mainly due to weathering. The relatively thin No.5 Seam was deposited during a short period of peat accumulation in a relatively unstable basin. The seam is of good coal quality but often friable. The average thickness were fully developed ranges between 1.5 m and 2.0 m. Only isolated small areas remain at Wolvekrans where the No.5 Seam is adequately developed to be considered for mining.

No.4L Seam (0.5 to 5 m) is present across most of the WMV area and is overlain by two lesser seams, firstly the poor quality No.4U Seam (No.4U excluded from Coal Resources), and secondly the good quality but thin No.4UA Seam. The No.4L Seam follows the No.2 Seam in economic importance at Wolvekrans. The No.4L Seam is mined in all the pits at Wolvekrans. Historically, the No.4L Seam was mined underground in some parts of the Wolvekrans.

No.3 Seam (0 to 1 m) is thin and erratically developed. The No.3 Seam is good quality but due to its thickness and erratic development it is uneconomic and not mined at Wolvekrans.

No.2 Seam (3 to 8 m) occurs throughout the Wolvekrans area with thicknesses greater than 3 m. In general, the sediments above the coal seams tend to be fine grained to argillaceous, and carbonaceous in places, and usually show an upward coarsening texture with increasing distance above the seam. A marker horizon of bioturbated siltstone is present above the No.2 Seam. In some areas, intra-seam partings are developed which result in the development of a No.2L seam split.

The No.2 Seam shows zoned coal quality variation in the vertical sense with higher and lower yielding zones developed. These quality differences led to the selective mining of the seam in historical underground mined areas of the No.2 Seam across most of Wolvekrans.

No.1 Seam (0 to 3 m) is the oldest of the coal seams and was deposited on the diamictite/tillite facies, which unconformably overlies the pre-Karoo basin floor, or directly onto the basin floor itself. It is relatively uniform but is variable in thickness. The coal is generally dull, with a tendency to form a cubic fracture. The No.1 Seam was also historically mined underground in some parts of the Wolvekrans.

Intra-seam partings are present in all coal seams and may comprise different lithologies including sandstone, siltstone and mudstone. They form discontinuous layers and lenses at different heights within seams and are discontinuous. They vary in size and shape and are difficult to predict and correlate.

Intrusives and faulting.
Numerous dolerite sills and dykes of Jurassic age intrude the Karoo sediments. Where sills transgress the strata, including coal seams, they have the effect of uplifting the overlying strata, giving rise to complicated structural configurations. These uplifted blocks give the appearance of being fault bounded due to the vertical displacement caused by the sill transgression. Coal adjacent to and along dolerite intersections is subject to burning and de-volatilisation.

A major linear intrusive structure, known as the Ogies Dyke, strikes east-west across the northern boundary of the Boschmanskrans ("BMK") resource area. A graben feature runs parallel to the Ogies Dyke, but will not influence future mining operations.

A large sill structure occurs to the south of BMK East and has devolatilised large areas of the No.2 Seam, as well as lesser amounts of the No.4L Seam.

The Steenkoolspruit pit area appears to be free of any major igneous intrusions. This area comprises virgin coal seams unaffected by historical underground mining. The coal seams however show significant roll structures where gradients may exceed 10 per cent, and variation in inter-burden thickness due to channel sandstones between the No.2 and No.2A Seams, as illustrated in Figure 5.9. The No.2 Seam also contains numerous intra-seam partings.

Dolerite sill intrusions are also present in the VanDyksdrift Central area where they have resulted in uplifted blocks and devolatilisation of adjacent coal seams. This uplifted area is excluded from the currently defined Coal Resource.

Faulting is generally minor with throws of less than 3 m. Fault planes are near vertical and easily negotiated in opencast operations. The majority of faults are associated with either dolerite intrusions, displacements in the graben structure, and along pre-Karoo ridge features. The only prominent faults at Wolvekrans are those associated with significant dolerite sill emplacement at Vandyksdrift Central and at BMK East.

While faults are rare and in most cases insignificant, seam floor rolls do occur and in places steep gradients require an adaption of the mine plan.

Coal seams preserved in the Middelburg area include the No.5, No.4UA, No.4U, No.4L, No.3, No.2U, No.2, No.2L, No.2A, No.1 and No.1A Seams, and are similar to the seams present at Wolvekrans. The main economic seams across the Middelburg mining area include No.1, No.2A, No.2 and No.4L Seams.

The numerous intra-seam partings are comprised of sandstone, mudstone and siltstone and form discontinuous layers and lenses at different heights within seams. They vary in size and shape and are difficult to predict and correlate.

Intrusions also occur, but to a much lesser degree, in the Goedehoop and Hartbeestfontein areas.

There are no known significant faults in the Middelburg area. Faulting is rare and throws are less than 3 m.

Rolling strata, with variable strike and dip direction, occurs in the southern part of the Hartbeestfontein area, and to a lesser extent in the Goedehoop and Klipfontein areas. The formation of these rolls is ascribed to the undulating nature of the underlying basement felsite of the Bushveld Igneous Complex. Severely rolling strata with dips up to 15o adversely affect mining operations may result in increased coal losses and dilution, and adjustments to the mine plan.



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Mining Methods


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Crushers and Mills

Milling equipment has not been reported.



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CommodityUnits2020 *201720162015
All production numbers are expressed as clean coal. * Average annual production reported in 2020

Production Costs

Commodity production costs have not been reported.

Heavy Mobile Equipment


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Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Jan 14, 2024
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EmployeesContractorsTotal WorkforceYear
...... Subscription required ...... Subscription required ...... Subscription required 2021
...... Subscription required 2017

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