Regional geology
All of the known coal deposits in South Africa are hosted in sedimentary rocks of the Karoo Basin, a large retro-foreland basin that developed on the Kaapvaal Craton and filled between the Late Carboniferous and Middle Jurassic periods.

The Karoo Supergroup is lithostratigraphically subdivided into the Dwyka, Ecca, Beaufort and Stormberg groups, succeeded by the Drakensburg Formation (SACS, 1980). The coals range in age from Early Permian (Ecca Group) through to Late Triassic (Molteno Formation, Stormberg Group) and are predominantly bituminous to anthracite in rank, which is a classification in terms of metamorphism under the influence of temperature and pressure.

The coal deposits of the Witbank Coalfield are restricted to rocks of the Vryheid Formation, which ranges in thickness from 70m to over 500m, being thickest in the northeast and east of the preserved outcrop area, to the south-southwest of the town of Vryheid, where the basin was the deepest.

The coal seams, from the base upward, include the No.1, No.2, No.3, No.4 and No.5 Seams. The No.1 Seam is best developed in the northern part of the Witbank Coalfield, where it is between 1.5m and 2.0m thick.

The No.2 Seam contains some of the best quality coal. Its average thickness is 6.5m in the main- central part of the Witbank Coalfield and thins to approximately 3.0m towards the west and east.

The No.3 Seam is poorly developed and is usually less than 0.5m thick. It is, therefore, not generally economically extracted.

The No.4 Seam varies in thickness from approximately 2.5m to 6.5m. In places, the seam is divided into the No.4 Lower, No.4 Upper and No.4 A Seams, separated by sandstone and siltstone/mudstone partings. The seam usually contains dull to dull lustrous coal.

The No.5 Seam has been extensively eroded over large areas, and where present has an average thickness of 1.8m, being between 0.5m and 2.0m thick The seam is generally a high quality, low phosphorus coal, and is a source of blend coking and other metallurgical coal.

Local geology
The surface geology over the Vanggatfontein area is dominated by outcrops and sub-crops of sedimentary rocks of the Ecca Group (Vryheid Formation), with Transvaal Supergroup (Hekpoort Formation) outcrops also present at the surface in the far east of the area.

The pre-Karoo basement to the area consists of rocks of the Transvaal Supergroup. Boreholes that have penetrated through the Dwyka Group into the basement intersect mainly Malmani Group dolomites, as well as metasedimentary rocks and lavas of the Hekpoort Formation of the Transvaal Supergroup. An unconformity in the order of 1,800Ma therefore separates the Transvaal Supergroup rocks from the overlying Karoo Supergroup. During this vast span of time the dolomites of the Transvaal Supergroup in particular were subject to a number of stages of karstification and weathering and this has an important impact on the nature of the overlying successions as discussed below.

Vanggatfontein is divided into an East Resource Block (ERB) and West Resource Block (WRB) separated by the D2543 provincial road which passes through the property. In places both the ERB and WRB host the complete sequence of the Witbank Coalfield coal seams, namely the No’s.1, 2, 3, 4 and 5 Seams, although the No.3 Seam is not usually developed and the No.5 Seam is eroded away in places. The stratigraphy of the ERB and WRB may be subdivided into three main sequences, these being a basal No.2 Seam Sequence, overlain by the No.4 Seam Sequence, which in turn is overlain by the No.5 Seam Sequence.

The Colliery mines the No. 5, No. 4 and No. 2 seams using truck and shovel rollover mining methods at an average rate of 340 000tpm run of mine (“ROM”). The No. 5 seam is processed through a 100tph plant for domestic metallurgical and boiler markets (No. 5 seam plant), whilst the No. 4 and No. 2 seams are processed through a 480tph plant which produces thermal coal for Eskom.

Mining is primarily performed using a drill and blast, truck and shovel methodology, using a combination of various hydraulic excavators, 40t articulated dump trucks (ADTs) and 100t rigid haul trucks. Coal mining is carried out simultaneously with the overburden removal. As the pit advances, the overburden dumps are rolled back into the pit, to fill the mined out voids as part of the continuous rehabilitation process. The hauling distance to the waste or burden dumps ranges between 0.1km and 2.0km and is maintained within this range to keep the cost of mining optimal. [01/31/2017, TR, p.132]

Coal processing
KEHL owns two CHPPs with processing capacities of 100tph and 480tph, respectively. The 100tph plant (No.5 Seam plant) processes RoM from the No.5 Seam, producing high quality products for domestic metallurgical and boiler markets, third party coal on short term contracts as well as No.2 and No.4 Seam coal as capacity allows. The 480tph plant processes RoM from the No.2 and No.4 Seams producing exclusively washed Eskom power station coal.

Processing method
Vanggatfontein was initially commissioned as a No.5 Seam mine as a coal supply agreement with Eskom had not yet been concluded. That said, the significantly different coal qualities of the No.5 and No.4 / No.2

No.5 Seam CHPP
This CHPP was designed to process coal from the No.5 Seam to produce sized products for the domestic metallurgical industry. It was commissioned in November 2010, and designed with a process capacity 0.6Mtpa of RoM using a single module DMS. The plant design ........