IMpunzi Complex
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.

Tweefontein Complex
The Dwyka Tillite is overlain by sediments of Ecca, Beaufort and Stormberg Groups. Coal measures are associated with the Vryheid Formation of the Lower Ecca Group of Permian age.

IMpunzi Complex
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.

Mpunzi 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.

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 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.

Tweefontein Complex
The Tweefontein North development includes all five seams present in the Vryheid Formation, however, only the No.1, No. 2, No. ........

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