South Africa

Dorstfontein Mine

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Overview

Mine TypeOpen Pit & Underground
StatusActive
Commodities
  • Coal (thermal)
Mining Method
  • Truck & Shovel / Loader
  • Bord-and-pillar
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Mine Life... Lock
SnapshotDorstfontein Coal complex (Dorstfontein West mine & Dorstfontein East mine) is part of the Katlego Operation (formerly Exxaro Coal Central Complex).

Production and financial data have not been publicly available since Overlooked Colliery Proprietary Ltd. acquired Katlego Operation in September 2021.
Related AssetKatlego Operation

Owners

SourceSource
CompanyInterestOwnership
Mmakau Mining (Pty) Ltd 26 % Indirect
Overlooked Colliery Proprietary Ltd 74 % Indirect
Dorstfontein Coal Mines (Pty) Ltd (operator) 100 % Direct
On 8 April 2021, Exxaro signed a sales and purchase agreement with Overlooked Colliery Proprietary Limited disposing of the ECC operation. All conditions precedent to the sales and purchase agreement were fulfilled and the transaction became effective on 3 September 2021.

Contractors

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Deposit type

  • Sedimentary

Summary:

Coal measures of the Highveld and Witbank coalfields are hosted in the Ecca Group, which includes the Vryheid and Volksrust coal-bearing formations. All coal seams in the ECC area are hosted in the Vryheid formation which ranges in thickness from 80m to 300m. There are five major coal seams present in the area, named from the base upwards as S1, S2, S3, S4 and S5.

A granitic basement high, which forms part of the Smithfield Ridge and is referred to below as the Central plateau, divides the DCM complex into two separate geological domains and the western and eastern limbs can be found on either side of this plateau. S1 is only developed in the central portions of the paleo-valleys, ranging in thickness from 0.1m to 2.5m. Underground extraction of this seam is considered uneconomic due to its highly variable thickness, inferior quality, isolated occurrence and coal devolatilisation. In the DCM complex, seam splitting is generally a provenance of detrital material resulting largely from the proximity of the seam to the Smithfield Ridge and, as a result, the S2 and S4 are further subdivided into S2L, S2U and S4L and S4U, respectively.

S2L is thinnest over palaeo-highs and thickest over troughs of palaeo-valleys. Two S2L thickness domains exist in the complex. In the west (DCMW), seam thickness ranges from 0.1m to 5m and, in the east (DCME) from 0.2m to 6.0m. In the north of DCMW, the S2L exists as a single coal horizon, generally devoid of stone partings. To the south of this block, an arenaceous parting splits the seam into an upper and lower subseam. The parting separating S2U and S2L in both the west and east attains a maximum thickness of 4.5m and, in the northern portion, a minimum of 0.2m with an average of 1.5m. S2U is considered uneconomic to mine separately by underground methods but is included for the opencastable blocks. Generally, S2L is the thicker of the two subseams and has better quality coal. As such, S2L is theoretically the mining target. However, practical mining of S2L is often problematic due to parting between two subseams S2L and S2U.

On the basis of seam thickness and coal quality, S4L is the main underground exploitation target in S4, which comprises coal and minor in-seam partings, and is characteristically banded with alternating dull and bright coal. The seam contains one in-seam parting of significant thickness and lateral extent with a thickness average of 0.2m but can reach 0.5m. Generally, the average thickness of S4L is 3.0m. S4U has an average thickness of 1.7m in the west and, in the east, the thickness is generally more than 1.0m, reaching 3.0m in the centre of the palaeo-valley. Seam S4U has a higher ash content and thus lower CV compared to S4L. Thickness of the S5 is generally over 1.5m. Due to a significant parting, the seam is considered uneconomic for underground extraction but can be considered for selective extraction in opencast.

Numerous Jurassic dolerites (dykes and sills) intrude the Vryheid formation at various stratigraphic levels in the area. These intrusions negatively influence the stratigraphy and coal qualities in places. The distribution of the lower coal seams are strongly influenced by basement topography while distribution of the upper seams is controlled by present-day topography. Most affected by basement topography are S1 and S2. Seams are often thin and sometimes pinch out over and against palaeo-highs. Strata (including coal) are often faulted, although displacements are rarely more than 1m. Structural displacements, resulting from intrusions of dolerite sills through seams, often complicate mining seams.

The DCM complex geology and grade continuity are largely influenced by palaeo-topography, present-day topography, surface weathering, seam thickness variation (mainly between DCMW and DCME), in-seam parting, in-seam washouts, dolerite intrusions in the form of sills and dykes, resulting in minimal to extensive zones of devolatilisation. These geological risks are well managed through extensive drilling in areas of concern, using downhole wireline logging for better definition, underground channel sampling incorporated as points of observation in the short-term model, underground face mapping generally used to track both vertical and lateral variations in the lithology to assist with reconciliations as well as structural interpretation and surface mapping, particularly of basement outcrops. The information collated from the various approaches is incorporated in the structural model, together with additional potential risks from other disciplines and represented in a GIS-based risk and opportunity domain analysis (RODA), allowing for a more integrated approach to risk management.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

Milling equipment has not been reported.

Processing

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Production

2021 production data is reported for the period January 1 to September 3th 2021.
CommodityUnits202120202019
Coal (thermal) kt  ....  Subscribe  ....  Subscribe2,161
All production numbers are expressed as clean coal.

Operational metrics

Metrics20202019201820172016
Coal tonnes mined  ....  Subscribe3.48 Mt of ROM coal2.89 Mt of ROM coal3.02 Mt of ROM coal3.3 Mt of ROM coal

Production Costs

Commodity production costs have not been reported.

Financials

Units20202019
Revenue M ZAR  ....  Subscribe 1,324  
After-tax Income M ZAR  ....  Subscribe -110  
Operating Cash Flow M ZAR  ....  Subscribe -212  

Heavy Mobile Equipment

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Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Oct 13, 2023
....................... Subscription required ....................... Subscription required Subscription required Oct 13, 2023
....................... Subscription required ....................... Subscription required Subscription required Oct 13, 2023

Aerial view:

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