The iMpunzi Complex falls within the southern margin of the central portion of the Witbank-Springs Coalfield. The coalfield is underlain by pre-Karoo formations, mainly Bushveld felsite. Historic glaciation events resulted in the deposition of tillite (Dwyka Formation) over most of the area. Within the Karoo Sedimentary Sequence the Ecca Group rests on top of the Dwyka Formation. In the Witbank-Springs Coalfields the coal bearing Vryheid Formation occur at the bottom of the Ecca Group conformably to the underlying Dwyka Formation.

The Dwyka Formation consists of tillite, siltstone and sometimes a thin shale development. The Ecca Group consists predominantly of sandstone, siltstone, shale and coal. The Vryheid Formation in the Ecca Group contains five bituminous coal seams, numbered as No. 1 to No. 5 from bottom to top. The No. 2, No. 4 and No. 5 seams are the most economical coal seams to mine in the Witbank-Springs Coalfield.

All opencast mining is undertaken using the strip mining method using draglines, and truck and shovel at the smaller open pits. All hard overburden (shale/sandstone) and coal are blasted using bulk explosives (heavy ammonium nitrate and fuel oil emulsion). The coal is transported by a fleet of trucks to the crushing and pillar screening plant.

The iMpunzi mining right incorporates the iMpunzi East area, consisting of the East pit, and the iMpunzi North area, comprising the North, Phoenix and Office pits.

iMpunzi North: Coal Resource depletion due to mining (-6.4Mt). Coal Resources reduction as a result of mining losses, including low wall losses, scalping and floor coal left behind (-0.3Mt).

iMpunzi North consists of the iMpunzi North Opencast (opencast dragline and truck and shovel operations in North and South pit) and iMpunzi Mini-pits (truck and shovel operations in the Phoenix, and Office pits). The Opencast Coal Resources include the No.1, No. 2 and No. 4 seams, whilst the Mini-pit involves only the No. 4 seam.

Coal Reserve depletion due to mining (-5.2Mt). South Pit triangle reserves moved to iMpunzi East, VDD South Pit (-6.6Mt). Adjusted face positions and coal mined outside mine plan account for a reserve increase of 2.0Mt.

iMpunzi East: Coal Resource depletion due to mining (-3.5Mt).

iMpunzi East consists of the iMpunzi East Opencast (opencast dragline and truck and shovel operations in the East pit). A large proportion of No. 2 seam and a small area of No. 4 seam have been previously mined by underground bord and pillar methods. The full seam is extracted through opencast mining methods – the lower zone of each seam was previously partially extracted by underground mining and the upper zone remains intact. Coal Reserve depletion due to mining (-3.8Mt). The VDD South Pit reserves (6.6Mt) have been considered as part of iMpunzi East (previously iMpunzi North).

iMpunzi consists of an opencast mining complex, a coal handling and preparation plant, and the iMpunzi dump reclamation operations feeding to the ATC coal handling and preparation plant, which produce a combined 7 million tonnes per annum, of which approximately 55 per cent. is exported.

The coal is transported by a fleet of trucks to the crushing and pillar screening plant (Golder, 2016b).

Arthur Taylor Colliery (ATC)
The operation has its own coal processing plant and has rail load-out facilities for coal transportation, via the adjacent Transnet railway.

Arthur Taylor Colliery Opencast Mine (ATCOM)
The coal mined at ATCOM is transported to the ATCOM Central Plant where it is washed and conveyed to the linear stockpile at ATC. From there, it is conveyed to a rapid load-out silo situated at ATC, from where it is transported via rail to Richards Bay for export (Jones & Wagener, 2014).