Summary:
The Zibulo Colliery is an underground and opencast mini-pit thermal coal mine.
Zibulo Colliery falls within the Springs-Witbank Coalfield, that comprises of sediments of the coal-bearing Ecca Group of the Karoo Sequence, which were deposited on an undulating pre-Karoo floor which had a significant influence on the nature, distribution and thickness of many of the sedimentary formations, including the coal seams. Locally the general lithological profile, up to, and including the deepest mine-able coal seam, comprises of soft overburden overlying coal seams 5 (shallowest) to 1 (deepest) (Licebo Environmental and Mining (Pty) Ltd, 2018). Below the No 1 coal seam is the basement, comprising a diamictite of glacial origin (Licebo Environmental and Mining (Pty) Ltd, 2018).
The entire sequence has been extensively intruded by pre-Karoo dolerites (for the regional area). The Ogies dolerite dyke runs in an east-west orientation across the centre of the Zibulo opencast mining area (Licebo Environmental and Mining (Pty) Ltd, 2018). Two other dolerite dyke intrusions were identified on the eastern edge of the project area running in a north to south direction.
Zibulo OC
Zibulo OC is located in the Witbank Coalfield where typically five coal seams are present. However, at Zibulo OC only three seams occur, which consist of, from the bottom upwards, the No 1 Seam sequentially to the No 4 Seam at the top. The No 5 Seam has been eroded and the No 3 Seam is not present. The No 4 Seam and No 2 Seam both contribute to the colliery’s export product.
Zibulo OC is sub-divided into two distinct domains, north and south, by the Strategic Fuel Fund (SFF) pipeline servitude. No faults or dolerites are present in the area. Granted WULs to mine the wetlands to the east and south are available.
Zibulo UG
Zibulo UG is located in the Witbank Coalfield where five coal seams are present. These consist of, from the bottom upwards, the No 1 Seam sequentially to the No 5 Seam at the top, with inter-seam partings consisting of mainly siltstone and sandstone, with thicknesses ranging between 1m and 20m. The No 2 Seam is currently the only underground contributor to the colliery’s export product.
Pre-Karoo paleo-highs influence the No 2 Seam thickness and elevation, particularly where the seam truncates against these paleo-highs.
The No 4 Seam and No 5 Seam are declared as RoMP and are considered to be economic Coal Resources for future mining, with the select No 4 Seam as a domestic product and the highly vitrinitic No 5 Seam as a possible metallurgical coal. However, the No 5 Seam potential is restricted by thickness, weathering and extensive sill influence.
Faulting is minimal across Zibulo UG, except for the major graben structure in the north, striking east-west across the colliery. The graben consists of a series of sub-parallel faults with varying throws along strike. The graben was also intersected in the neighbouring underground workings of Khutala Colliery and has a magnetic signature clearly visible on the aeromagnetic survey. Five fence line patterns were drilled to better define the extent of the graben at Zibulo UG.
Dolerite intrusions and associated stringers occur throughout the area and large sills appear close to the surface, affecting mostly the No 5 Seam.