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.

The iMpunzi Complex consists of four (4) collieries or sub-sections, namely: ATC, Phoenix Colliery, ATCOM, and ATCOM East. Coal mining within the complex was initiated at the Phoenix Colliery in 1936. Operations at all four colliers have historically been underground. However, all underground operations ceased in 2008, and all remaining operations are opencast.

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.

Arthur Taylor Colliery
Operations at ATC traditionally consisted of underground workings but also included an opencast operation called the Butterfly Pit. The operation has its own coal processing plant and has rail load-out facilities for coal transportation, via the adjacent Transnet railway. Underground mining of the No. 2 and No. 4 seams at ATC ceased in 2008. Opencast strip mining operations at Butterfly Pit commenced in 2009 but have since concluded and now has been rehabilitated.

Additional opencast strip mining is proposed at the ATC Office and Phoenix Pits. Coal will be mined from these pits utilising the truck and shovel method. The ATC Office Pit 1 is located on the site of the iMpunzi Complex offices, and the office will have to be demolished before operations can commence. The coal mined at the ATC Office and Phoenix Pits will be processed at the ATC and ATCOM Central Plant.

Arthur Taylor Colliery Opencast Mine
The ATCOM area consists of both opencast and underground coal mining operations. Operations at the ATCOM area commenced in 1991, and the extent of the South Pit covered the original course of the Steenkoolspruit. A permanent river diversion was constructed to divert the Steenkoolspruit around the South Pit.

Current mining activities at ATCOM comprise of opencast mining of the North Pit (pillar extraction from old underground workings). Mining at ATCOM is expected to cease in 2025. 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.

Phoenix Colliery
The Phoenix area is situated to the south-west of ATCOM and east of the ATC, and coal has been mined here since 1936. The Phoenix area consists of the slurry lagoon area, discard facility (extension of the ATCOM/Phoenix dump located on the old Phoenix Plant area) and underground areas. Mining activities at the Phoenix Colliery ceased in 2008. All of the facilities at the Phoenix Colliery are inactive except for the Phoenix 1 seam, where mine affected water is stored.

Arthur Taylor Colliery Opencast Mine East
The mining operation includes opencast mining of historical underground bord and pillar operations, previously owned by BHP Billiton Energy Coal South Africa. The new mining operations are situated near Vandyksdrift (VDD) and are known as ATCOM East. Mining at ATCOM East makes use of truck and shovel as well as dragline operations. The ATCOM East mining operations are divided into five areas, namely:

-Steenkoolspruit Pit: Mining by GOSA commenced at the Steenkoolspruit Pit in January 2009. The current LoM plan indicates that mining will resume in 2025 and end in 2029. This pit will be mined by dragline;
-River shaft South Pit: It is proposed to commence mining at river shaft South Pit in 2021 and mining will continue until 2031. Due to the restricted area of this pit, it will most likely be mined using the truck and shovel method;
-VDD South Pit: This is the largest pit and will be mined concurrently with the River South Pit. Mining is anticipated to continue until 2035. The pit will be mined by dragline;
-River shaft West Pit: Mining of this pit was scheduled to commence in 2014 and continue until 2024;
-VDD West Pit: This pit will be mined using the truck and shovel method from 2024 until around 2033.

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).