The coal deposit at Matla forms part of the Highveld coalfield. The coal seams are found in the Vryheid formation of the Karoo Supergroup. The stratigraphy sequence in the Matla area includes five coal seams that can be easily correlated with seams found in the Witbank coalfield. Coal seams in the area are generally flat and continuous, with subsequent igneous activity resulting in displacements and devolatilisation of coal seams at places.

The principal economic seams currently exploited are S2 and S4, with mining of seam 5 (S5) terminated in 1998 due to high levels of contamination and subsequent increase in abrasive index. The Matla mining area is characterised by two distinct dolerite types, the B8 (porphyritic) and B4 (olive-rich) types which have varying effects on seam displacements and coal burning and devolatilisation. A dolerite sill with an average thickness of 10m is generally found above S5 in mine 2 and 3, however, the sill intersects the coal seams and underlies S2 in mine 1 and S4 on the south-western part of the Reserves. This sill has burned and devolatilised S2 on the southern part of the mining area in mine 1. Floor rolls have been encountered in S2 workings and created some challenges in some mining sections. The floor rolls strike NE-SW vary in width between 50m and 200m and have amplitudes up to 1.5m. The floor rolls are more prominent if the seam floor is close to the basement contact. Sandstone lenses encountered are generally less than 0 ........

Matla comprises three underground production facilities: mine 1, mine 2 and mine 3. All three are long-life assets, each with a specific operating capacity comprising conventional coal circuits to produce bituminous coal. Work at mine 1 was stopped in 2015 due to pillar instability but an Eskom-approved project to relocate mine 1 access is currently in the implementation phase. Mine 2 and mine 3 use both bord-and pillar and shortwall methods to mine seam 2 (S2) and seam 4 (S4) coal seams.

Matla extracts 2 seam select and the lower-quality but somewhat thicker 4 seam in a specific scheduled relationship to blend and honour the volume and quality requirements of the Eskom agreement. It is therefore of the utmost importance to have adequate access to quality Coal Reserves to ensure the correct volumes are scheduled for the short, medium and long-term strategies. Both coal seams’ mineable Reserves are rapidly diminishing within mines 2 and 3 and the unfortunate closure of Mine 1 due to pillar instability in 2015 placing a burden on the operation to comply with contractual expectations. However, Exxaro has, since closure of Mine 1, accelerated exploration and outlined 2 seam and 4 seam Coal Resources that will be accessed through either new or existing infrastructure.

During this time, annual mining targets were supplemented by the identification of additional potential mineable areas, prioritising exploration activities, and through innovative and adaptable ........

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