Seriti Power (Pty) Ltd. owns and operates the New Vaal, New Denmark, Khutala, Kriel, Pegasus, Naudesbank, Klipspruit, New Largo, Middelburg Mines Services (MMS) and Braamspruit Project.
Seriti holds a 90% interest in Seriti Power (Pty) Ltd., while an Employee Trust and Community Trust each hold a 5% interest.
Seriti Resources Holdings (Pty) Ltd.) is a broad-based, 92% black-owned and controlled South African energy company. It is co-owned by Masimong Group Holdings (Pty) Ltd, Thebe Investment Corporation (Pty) Ltd, Zungu Investments Company (Pty) Ltd, Community Investment Holdings (Pty) Ltd, and Coalzar (Pty) Ltd.
- subscription is required.
Summary:
Klipspruit
Coal seams preserved in the Klipspruit area include No.5, No.4U, No.4L, No.3, No.2 and No.1 Seams. As a result of the topographic surface sloping to the north, all of the coal seams except for No.2 and No.1 Seams have been affected by weathering. This is especially true of the No.5 Seam, which is almost totally lost to erosion north of the Ogies Dyke.
A dolerite dyke has been identified in the Bankfontein area, which has affected Coal Resources mainly in the No.4U Seam. This was the result of deep weathering adjacent to the dyke.
The Ogies Dyke is a well-known post-Karoo intrusive structure that extends for some 70 km in an east-west direction. It forms the southern boundary of the main Klipspruit opencast resource area, and separates it from the Klipspruit South resource area. The dyke varies in thickness from 40 m to 70 m and dips steeply to the south. It does not vertically displace the coal seams.
Middelburg Mines Services (MMS)
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.
Khutala
The No.1 and No.2A Seams are either absent or only locally developed with restricted extents across the area due to elevation differences in the palaeo-floor which consists of either basement felsite or Dwyka Formation.
Two prominent hilltops within the Khutala boundary represent major felsite palaeo-high ridges that truncated the coal measures during deposition. Seam dips can reach 15° on the flanks of palaeo-highs.
The No.4L, No.3, No.2A and No.1 Seams are not economically significant. These seams are either too thin, inconsistently developed, or of too poor quality to be considered.
In general, the coal-bearing strata are flat lying with little structural disturbance to the coal seams. However, a major graben structure bisects the Khutala property striking northeast-southwest and effectively divides the property into distinct northern and southern areas. This structural feature comprises a down faulted block with throws up to 16 m and is on average 120 m wide.
A number of identified dolerite dykes transect the property and have led to coal devolatilisation in immediate proximity to the dykes. The dykes are generally less than 2 m in thickness, are near vertical and cause fracturing and deeper than normal weathering along their contacts. The dykes do not pose a material issue to mining.
Intra-seam partings comprised of sandstone, mudstone and siltstone are prevalent in the No.2 Seam south of the graben, and mainly south of the No.2 underground workings. These discontinuous layers and lenses occur at different heights within the seam and are difficult to correlate. Argillaceous parting material is present mainly towards the top half of the seam with the sandstone parting concentrated near the bottom of the No.2 Seam. The sandstone lenses vary in size and shape and are difficult to predict. These hard lenses can be as small as 100 m2 and present cutting problems for Continuous Miner sections. The thickness of these lenses varies from centimetres up to 2.8 m.
The No.5 Seam is consistently developed across Khutala area, and where absent is mainly due to weathering effects and to a lesser extent termination against palaeo-ridges. This good quality bright-banded coal with an average seam thickness of 1.95 m and is not dedicated to Eskom.
The depth of cover above the seams generally increases to the south of Khutala. The depth to the roof of the No.4U Seam is approximately 100 m along the southern edge of the property while the depth to the No.2 Seam is approximately 130 m and is approximately 87 m for the No.5 Seam.
The parting thickness between the two top seams is fairly constant while the thickness between the No.4U and No.2 Seams increases from approximately 10 m in the north to 20 m in the south.
Kriel
The majority of the coal mined at Kriel Colliery is from the No.4 Seam. Sandstone is the dominant sedimentary rock unit and adjacent to the coal seam occasionally includes thin alternating layers of carbonaceous shale. The total thickness of the No.4 Seam in the Kriel coal field is generally between 4 and 5 m thick, where the top seam attains a thickness of 1.5 to 2 m. The No 4 seam is regionally overlain by a thick interlaminated shale-sandstone/siltstone and underlain by a typical white Ecca sandstone layer. Glauconitic sandstone, indicative of transgressive marine periods, is present above the Nos. 4 and 5 coal seams, forming useful stratigraphic markers (Zhao, 2010).
New Denmark Colliery
The NDC reserves occur within the Vryheid Formation of the Ecca Group within the Karoo Sequence. The thickness of the sediments underlying the No. 4 coal seam varies between 50 and 300 m.
The No. 4 coal seam is the only economically viable coal mining horizon that has been, or will be, mined at NDC. The No. 4 coal seam lies at a depth of approximately 200 m below surface, and has an average seam width of 1.85 m and ranges between 1.0 and 2.80 m. As a result of relatively poorer quality towards the upper part of the seam, it is found that the coal qualities improve in thinner coal areas where the upper lower quality portion of the seam has been washed out.
New Vaal colliery
The New Vaal colliery coal reserves are located in the northernmost part of the Vereeniging – Sasolburg coalfield in an area locally referred to as the Cornelia coalfield. The coalfield field occurs on the northern edge of the Karoo basin.