The primary geology and stratigraphy at Khutala is typical of the Witbank Coalfield, refer to Figure 5.4. The development of the No.2 and No.4U Seams occurred mainly in a broad valley of low topographic relief where coal seams terminated towards the east and west of the property. This thinning or absence of coal seams towards the east and west is due to a gentle rising of the pre-Karoo relief. Coal Resources in the No.2 and No.4U Seams within the Khutala mining right area is contracted to Eskom and mined coal is delivered raw to Kendal Power Station.

The No.1 and No.2A Seams are either absent or only locally developed with restricted extents across the area due to elevation differences in the palaeo-floor which consists of either basement felsite or Dwyka Formation.

Two prominent hilltops within the Khutala boundary represent major felsite palaeo-high ridges that truncated the coal measures during deposition. These no-coal areas are shown in Figure 5.44 and their effect on coal seams is illustrated in Figure 5.45. Seam dips can reach 15o on the flanks of palaeo-highs.

The No.4L, No.3, No.2A and No.1 Seams are not economically significant. These seams are either too thin, inconsistently developed, or of too poor quality to be considered.

In general, the coal-bearing strata are flat lying with little structural disturbance to the coal seams. However, a major graben structure bisects the Khutala property striking northeast-southwest and effectively divides the property into distinct northern and southern areas, as shown in Figure 5.44. This structural feature comprises a down faulted block with throws up to 16 m and is on average 120 m wide.

A number of identified dolerite dykes transect the property and have led to coal devolatilisation in immediate proximity to the dykes. The dykes are generally less than 2 m in thickness, are near vertical and cause fracturing and deeper than normal weathering along their contacts. The dykes do not pose a material issue to mining.

Intra-seam partings comprised of sandstone, mudstone and siltstone are prevalent in the No.2 Seam south of the graben, and mainly south of the current No.2 underground workings. These discontinuous layers and lenses occur at different heights within the seam and are difficult to correlate. Argillaceous parting material is present mainly towards the top half of the seam with the sandstone parting concentrated near the bottom of the No.2 Seam. The sandstone lenses vary in size and shape and are difficult to predict. These hard lenses can be as small as 100 m2 and present cutting problems for Continuous Miner sections. The thickness of these lenses varies from centimetres up to 2.8 m.

Intra-seam parting within the No.4U Seam consists mainly of argillaceous material which poses less of a problem for mining operations.

The No.5 Seam is consistently developed across Khutala area, and where absent is mainly due to weathering effects and to a lesser extent termination against palaeo-ridges. This good quality bright-banded coal with an average seam thickness of 1.95 m and is not dedicated to Eskom.

The depth of cover above the seams generally increases to the south of Khutala. The depth to the roof of the No.4U Seam is approximately 100 m along the southern edge of the property while the depth to the No.2 Seam is approximately 130 m and is approximately 87 m for the No.5 Seam.

The parting thickness between the two top seams is fairly constant while the thickness between the No.4U and No.2 Seams increases from approximately 10 m in the north to 20 m in the south.

The mine is predominantly an underground bord and pillar mining operation.

The underground mine is accessed by a large diameter vertical shaft for men and materials and there is an access decline which is used to transport the coal on a conveyor from underground to the surface stockpiles. In total there are currently 12 working areas (known as sections), with eight sections in the No.2 Seam and four sections in the No.4 Seam. The current underground mining method is to use modern mechanised continuous miners in all working sections. Both the No.2 and No.4 Seams are mined using continuous miners, mechanised roof bolters, electric shuttle cars and feeder breakers. The broken coal is loaded onto a network of conveyor belts, which transport the coal to surface.

Each continuous miner section comprises nine roadways; seven of these are used as intake airways and the remaining two as return airways. In plan view, this creates chequerboard pattern of ‘bords’ (comprising headways and cut-throughs), which provide access, and blocks of uncut virgin coal blocks (‘pillars’). The pillars support the overlying strata, while the headings/cut-throughs are supported by roofbolts. The depth of working is the key determinant impacting on the dimensions of the pillars and the size of each bord. As depth increases so does the size of the pillar, which then affects extraction and production rates. This nine-road configuration minimises the frequency of belt extensions, without infringing on the trailing cable length of machines when mining the extremities of the panel. The coal seam is mined with thick seam continuous miners.

Coal is conveyed to the surface where it first passes through a destoning facility before being conveyed through to a single stockpile. The coal is then transferred directly by conveyor to Eskom’s Kendal power station.

There is a small opencast operation in the North section of the Mining Right known as Portion 16, which is currently mined via a traditional truck and shovel mining technique for extraction of the coal seams. This operation extracts coal from the No.5, No.4 and No.2 Seams.

Mining uses a series of strips and cuts over a wide area, where the surface is relatively flat and the coal seams comparatively shallow. The stripcut initially started as a boxcut with 40 m access ramp, which was then advanced to a 500 m strip cut with ramps being moved and placed as space became available in the low wall.

A contractor has been appointed to mine the opencast, with the capacity based on volumes that were mutually agreed by the contractor and SAEC’s Khutala Integrated planning department. Currently, opencast mining at Portion 16 has been running at an annual rate of 1.2 Mtpa, with mining forecast to be complete by December 2014. The operation is concentrated in a shallow subcropping area with an average strip ratio of 3:1 bcm/t ROM.

The No.5 Seam is hauled to Klipspruit, while the No.2 and No.4 Seams are hauled to a conveyor system where it is combined with the underground coal.

Beneficiation facilities consist of a crushing plant for the energy coal with a combined nominal capacity of in excess of 12 Mtpa. A separate smaller crusher and wash plant with a nominal capacity of 1.5 Mtpa is used to beneficiate the coal supplied from the opencast operation. Coal from the No.2 and No.4 Seams is transported via overland conveyor to the Kendal Power Station.