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Muja Mine

One of the largest open cut mines in the world producing around 1.5 to 1.8 million tonnes of coal per year.

Location: 18 kilometres south east of Collie, Western Australia.

Year mining commenced: 1954

Year mining concluded: 2010

Type of mining: Open cut

Type of coal: Primarily thermal coal however several coal faces are available at different depths providing flexibility for blended coal. This can be delivered direct to clients without the need to rehandle.

Primary use of Muja Coal: Thermal coal is primarily used for steam raising to produce electricity. Muja Mine’s total output is delivered directly to Muja Power Station. Muja coal is sold and delivered uncrushed as ‘Run Of Mine’ (ROM) product. Open cut

Mine summary: Muja Mine is advancing to the northwest in blocks that are the width of the coal measures’ exposure (up to 1.5 kilometres) and 150 metres to 180 metres wide. These blocks are developed through the full thickness of the Muja strata to the lowest economically mineable seam.

The seams lie in a synclinal (spoon shaped) formation that determines the shape of the mining floor and eight seams are extracted. The Hebe seam that is 13 metres thick and is at the bottom of the sequence represents about 50% of the mine’s total reserves.

At any time there are generally three blocks under development. The highest (most north westerly) block is mining the Nakina Formation. This material is hauled along a road on the west pit wall to high level in-pit dumps. The middle block is working down through the upper seams of the Muja Coal.

The lowest block exposes the Hebe seam, which usually forms the bulk of uncovered coal reserves. This overburden is hauled across the block to low-level in-pit dumps. This arrangement minimises the vertical movement of overburden materials, which would otherwise slow down trucks, reducing productivity and increasing fuel consumption.

The availability of several coal faces at different levels gives the mine flexibility in delivering blended coal directly from the mine without the need to rehandle it. It also gives the ability to schedule an orderly flow of coal.

The Muja Mine reached the end of its mine life in mid 2010.

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