The coal measures of the North Block Complex occur on the eastern edge of the Witbank coalfield, within the Permian-age Vryheid formation of the Ecca Group in the Karoo Sequence. The Witbank coalfield is situated in the northern part of the Main Karoo basin and extends about 190km west-east between Brakpan and Belfast and about 60km north-south between Middelburg and Ermelo.

The main Karoo Basin:
- Was filled between the Late Carboniferous and Middle Jurassic periods;
- It is lithostratigraphically subdivided into the Dwyka, Ecca and Beaufort Groups, succeeded by the Molteno, Elliot and Clarens Formations and the Drakensburg Formation (volcanics);
- The coal bearing Ecca Group has been divided into three sub-units: the Pietermaritzburg; Vryheid and Volksrust Formations.

The Witbank Coalfield:
- The coal-bearing Vryheid Formation attains a thickness of 70m to 200m in the Witbank Coalfield;
- Here the Vryheid Formation consists of five coarsening-upward sequences with coal seams associated predominantly with the coarser grained fluvial facies at the top of each sequence;
- The No. 5, 4, 2 and 1 coal seams are of economic interest.

NBC (Glisa) mine resource area is close to the eastern edge of the Witbank Coalfield, in the northern part of the main Karoo basin. All Witbank Coalfield seams, i.e. S1, S2, S3, S4 and S5, occur in the Glisa area, with S2, S3 and S4 being economically important. Stratigraphy consists predominantly of the different coal seams separated by fine and medium to coarse grained sandstone, with subordinate mudstone, shale, sandstone and carbonaceous shale.

The thickness of the coal seam ranges from 0,5m to 3,1m, averaging 2,3m. The coal seam is overlain by medium to fine-grained sandstone with shaly bands. On top of the whole succession is overburden material comprising sandy soil and regolith. The average total depth to coal is relatively shallow at 10,7m and the maximum depth to top of coal is around 17,8m.

The main target Seams (S5, S4, S3, S2, & S1).

At Glisa, the S5 and S1 is sporadically developed while the S4, S3 and S2 is fairly well developed and consistent throughout the mining area extending approximately 3.5km along strike and 2.5km perpendicular to strike with an approximate average combined seam thickness of 15m.

The depth of cover to the S4 seam ranges from 2.3m in the northwest to 16m in the southeast.

The depth of cover to the S2 seam ranges from 25m in the northwest to 45m in the southeast.

The depth of cover to the S1 seam ranges from 28m to 45 in the northwest.

At Eerstelingsfontein, the S2 occurs as an erosional remnant on high ground, at shallow depths extending approximately 1km along strike and 2km perpendicular to strike with an approximate average seam thickness of 2.2m the depth to cover ranges between 10.5m and 18m on average.

At Paardeplaats, the S1 occur as thin bands while the S5 is only developed in the eastern part of portion 30, which is the area of interest. The S4, S3 and S2 seams are fairly well developed and consistent throughout portion 30, extending approximately 1.5km along strike and 1.5km perpendicular to strike with an approximate average combined seam thickness of 9m.

The depth of cover to the S4 seam ranges from 11m in the northwest to 38m in the southeast.

The depth of cover to the S3 seam ranges from 17m in the northwest to 49m in the southeast.

The depth of cover to the S2 seam ranges from 28m in the northwest to 60m in the southeast.

The primary operation is the Glisa mine, a multi seam open-cast mining operation 5km west of Belfast in the Highveld region of Mpumalanga.

The Eerstelingsfontein block to the south-east of Glisa comprises gently sloping topography. The coal resource here is contained in a single seam, S2. This seam occurs as an erosional remnant on high ground at shallow depths, suitable for open-cast mining.

The Paardeplaats Section is an operational section that adjoins the Glisa Section. Mining is undertaken by opencast mining methods.

As RoM reduces at the Glisa Section, the shortfall will be addressed through coal mined at the Paardeplaats Section. The Paardeplaats Section is an open cast mining operation where bench mining techniques are employed to access the coal seams. The 2 Seam Burden is removed with Dozers doing roll-over of the 2 seam burden into the previous 2 seam voids, and the upper burden seams are removed with the truck and shovel mining method. Coal seams 4, 3 and 2 will be mined for processing. Seam 1 appears in certain areas only and is highly weathered and contaminated with inseam shales and is not suitable to mine and will be left in situ in the pit.

The North Block Complex infrastructure consists of a Dense Medium Separation coal beneficiation plant and four crushing and screening plants (two of which will be transferred to NBC and two of which are owned and operated under long-term contracts), a water treatment facility and a rail siding that provides direct access to the Richards Bay Coal Terminal.

Glisa Section
Coal is crushed and screened at stationary plants whilst other coal products are processed at the main Crushing, Screening and Washing Plant (CSWP) located in the Glisa Section.

Water Treatment Plant
The WTP for the Glisa Section spans an area of approximately 0.67 ha on Portion 24 of Paardeplaats 380JT and is fully operational. The design treatment capacity of the WTP is 1.5 megalitres per day (Ml/d) on average over a 30-day cycle, equating to an average of 62.5 cubic metres per hour (m³/h).

The WTP processes entail chemical precipitation in combination with Ultrafiltration ( ........