Khwezela Operation (Landau and Kleinkopje Collieries) consists of two sections, namely the Kromdraai Section and the Navigation Section (Navigation West extention).

The eMalahleni area is underlain by the Karoo supergroup. The Karoo Supergroup comprises mainly a sedimentary succession of sandstone, siltstone, shale, mudstone, coal, diamictite and tillite. The Karoo Supergroup is lithostratigraphically subdivided into the Dwyka, Ecca and Beaufort groups, succeeded by the Molteno, Elliot and Clarens formations and the Drakensburg Formation. The Ecca Group comprises successions of formations which consists of sandstone, shale and coal and were developed within the Karoo basin locally. A number of intrusive dykes are known to occur within the study area. The positions of the dykes have been interpreted from geophysical surveys, but have mostly been delineated through mapping when intersected in the underground workings (Groundwater Complete, 2013).

The thickest portions of the Ecca Group were deposited in the southern Karoo basin in contrast to the relatively thin sequence which is now preserved in the East Rand. This succession of sedimentary rocks generally overly the well-consolidated conglomerates/diamictites of the Dwyka Formation, but in places the Ecca Group rocks rest directly on the felsites and granites of the pre-Karoo Basement rocks. Igneous intrusions of late Karoo Supergroup age in the form of dolerite dykes and sills also occur through the sedimentary succession. The sills usually precede the dykes, with the latter being emplaced during a later period of tensional forces within the earth’s crust. Tectonically, the Karoo sediments are practically undisturbed. Faults are rare. However, fractures are common in competent rocks such as sandstone and coal.

The sediments of the Vryheid Formation overlie an uneven Dwyka floor, which is controlled by the topography of the pre-Karoo platform upon which the Karoo sediments were deposited. The Vryheid Formation is present throughout the Witbank Area. At their thickest these sediments attain some 120 – 140m and can contain a number of coal seams of which four are considered to have economic potential. This area is known as the Witbank Coal fields.

The Navigation West Section is situated in the northern part of the Witbank coalfield. The coal measured forms part of the Vryheid formation of the Ecca group. All five coal seams, common to the Witbank coalfield, are present in the Navigation West Section area. The No. 4 Seam is suitable for mining by opencast methods. The No. 2 Seam is mostly thin and of moderate to low quality, as are the remaining No. 3, 4U and 4A Seams. The No. 5 Seam ‘sub-outcrops’ near the eastern boundary of the proposed mining area, and although of good quality, is not laterally extensive enough over the Navigation West Section to include in the mining plan.

The No. 4 Seam dips predominantly to the east, but also to the west (in the extreme west) as it is draped over a regional Pre-Karoo basement high. It is over the western part of the area that the No. 4 Seam is completely weathered as a result of its close proximity to surface. This ‘no coal’ area forms a major indent into the South Block and had a defining influence on the mining layout possibilities. The topography to the west, influenced by the upper reaches of the Grootspruit valley, dips fairly steeply towards the west, resulting in a sub-outcrop of the No. 4 Seam. To the east, the various seams dip at about 30 minutes towards the Greenside Colliery underground reserves, where all of the major seams have been preserved and mined to some extent.

Borehole logs of the geological successions encountered in vicinity of the Navigation West indicate a lithology of:
- Unconsolidated material between 0- and 4mbgl.
- Loose and weathered sandstone between 4- and 9mbgl.
- Coal between 10- and 15 mbgl.
- Shale and or sandstone between 15- and 20mbgl.

Kleinkopje Colliery.
Five main seams that are numbered in order of deposition from No.1 seam to No. 5 seam are present at Kleinkopje Colliery, this being typical of the Witbank Coalfield1. The coal- seams are separated by sediments of shale, sandstone and siltstone. The coal reserves of the mine are predominantly found in the No. 1, 2 and 4 seams1. There are limited reserves in the No. 2 Lower and No. 5 seam.

Coal is mined at Landau Colliery from the No.1, 2, and 4 Seams of the Witbank Coal Field.

The mineral to be mined, as indicated above, is that of coal to be mined from the No.4 Top Seam, the No. 4 Select Seam and the No. 5 Seam.

Kleinkopje Colliery is an opencast mine that uses strip and shovel method to mine the remainder of pillars left during underground mining. Mining is currently being carried out in four pits: 2A North (No. 2 and 4 seams), 2A South (No. 1, 2 and 4 seams), 5 West (No. 1, 2 and 4 seams) and 3A North (No. 2 and 4 seams) with plans for mining a new pit called the Z Pit from 2006.

Coal is mined at Landau Colliery from the No.1, 2, and 4 Seams of the Witbank Coal Field using opencast methods. Landau Colliery proposes to extend the Life of Mine at the Navigation Section by expanding the mining of the Navigation West: South Block opencast pit.

Mining at Navigation West Section is currently done at the North and South Block and coal is crushed and washed at the Ngwenya Plant within the boundary of the Navigation West Section.

As part of the opencast roll-over mining method, the spoils are rehabilitated as the mining operation advances, which are maintained so as to ensure that the rehabilitation of the disturbed area is no further than three cuts behind the active mining void.

For each strip, the topsoil, subsoil, and overburden is removed sequentially. Topsoil is removed and stockpiled separately or live placed where permitted for rehabilitation. Not including the boxcut, the subsoil is hauled around the pit, dumped and levelled to backfill previous voids. The hard overburden is blasted into the previous void and moved by combination of Dragline, dozers and truck and shovel to expose coal. The exposed coal is then removed and the No. 4 Seam will be 'split-mined' in a No. 4 Top Seam and No. 4 Select Seam horizons.

The No. 4 Top and select Seams are blasted simultaneously and loaded separately to separate the two grades of coal. After coal removal overburden and subsoil is selectively dumped behind the direction of progressive mining, before being reshaped. Thereafter, topsoil will be replaced and the backfilled void will be rehabilitated.

The No. 4 Seam in the Navigation West - South Block consists of a low quality upper section (No. 4 Top Seam) and a higher quality lower section referred to as No. 4 Select Seam. In some areas of the pit the 5 seam is present. The No. 5 and No. 4 Top Seam is loaded, crushed and transported to Eskom, or to one of the municipalities generating their own power e.g. Rooiwal. The lower No. 4 Select Seam is loaded and crushed prior to being hauled to the Navigation West Beneficiation Plant for processing aimed at the 5850 export market.

The No. 4 Select Seam ROM coal that is mined from the Navigation West Section is screened on-site at the Navigation West Section Beneficiation Plant the discards are backfilled at the bottom of the mined out pits to assist in attaining a positive volume balance for the mined area.

There are two plants at Navigation Section where coal can be processed and both will be utilised for the proposed Navigation West – South Block Extension Project. The Ngwenya Plant is located within the boundary of the Navigation West Mini pit on Portion 2 of the farm Elandfontein 309 JS. The other plant is the main Navigation Beneficiation Plant located on Portion 23 of the farm Blaauwkrans 323 JS near the old Navigation dump.

The washing plant is primarily subdivided into Wemco drum, cyclone and fines sections respectively. Feed from run of mine (ROM) is subjected to banana screening to separate at 12 mm cut size. The oversize is fed into a drum feed silo while the undersize reports to a different silo, from which it is fed into a DSM cyclone plant. The final product from the three sections is combined and sent to the rapid loading terminal (RLT) and railed to Richards Bay Coal Terminal (RBCT) at calorific value of 27.40 MJ/kg on air dry basis, top size of 50 mm and total moisture of 8%.

The layout of Kleinkopje plant commences at the raw coal tipping area, where coal can be tipped either on the A, B or C tip. The tipped material is then sized down to 150 mm through primary crushing Bradford breaker. The oversize is then subjected to a jaw crusher that also reduces the material size to a top size of 150 mm.

The stockpiling is done in chevron pattern to allow proper and even blending of raw material. The bucket-wheel reclaimers are then utilized to reclaim raw coal from the stockpiles through the banana screens which classify coal for the drum plant and cyclone plant silos.

The Wemco drum section is divided into five modules, namely, module 3, 4A, 4B, 5A and 5B. The oversize material reports to Wemco drum plants from which separation according to gravity takes place. After separation, the product and discard material report to their respective drain and rinse screens where medium recovery takes place before the material is transported either to a product or discard silo.

A single compartment Wemco drum is a separation bath that consists of a steel shell typically supported from four rollers in a longitudinal operating position. Inside, the shell is equipped with a set of lifting scoops that are perforated to allow drainage of medium as it rotates. In addition to the lifting scoops, the internal part of the drum consists of a feed chute, sinks launder, steel and rubber skirtings and medium addition points.

Raw coal enters in the feed end, into the magnetite-water mixture known as medium. Separation starts taking place immediately, with the heavier material sinking to the bottom of the shell and the lighter material floating. As the drum rotates, and the lifters fitted inside carry the discard to the sinks launder from which it flows onto a drain and rinse screen. The product floats with the medium out on the discharge end of the drum. The maximum size of coal that can be handled in the Wemco drum depends on the size of the whole shell, the inlet and outlet diameters as well as lifting scoops. A top size of 250 mm has been treated in the coal industry, whereas 150 mm seems to be more common (Wills, 2006). The Wemco drum can handle as much as 400 ton per hour feed, with approximately 20–25 ton per hour per m2 pool area with very good separation efficiencies.

Wemco drums present several advantages that make it a separator of choice over other dense medium washing baths. These include amongst others the following:
- A sharp separation can be obtained at various relative densities.
- High efficiencies are achievable with large amount of near gravity material.
- The operating density can be easily reached and controlled.
- A large range of particle size can be handled very efficiently.
- Changes in feed rate and quality can be treated with a high level of confidence.
- The drum can handle large quantities of feed per square metre per hour.

ROM coal mined at the Navigation West Section is hauled to the Ngwenya Plant, where is offloaded at the ROM tip and is crushed and stockpiled before being transported to the domestic market(s). It is proposed that the existing crusher at the Navigation West section will be upgraded with a new secondary, reversible 1800 feeder.