Bengalla

Mining and processing

Bengalla's Mining Lease covers an area of approximately 12 square kilometres with eight seams of significance being mined.  Coal seams vary from 0.3 metres to 11 metres in thickness, and the coal mined is thermal coal most suited as an energy source for electricity generation.

The strip mining method is used at Bengalla.  This method of mining is used when coal seams are close to the surface and in a consistent flat lying orientation.  Strip mining involves digging a 'trench' to expose the coal seam with the waste material (overburden) from the excavation placed adjacent to the trench.

Before mining can begin, the topsoil is removed and is stockpiled for reuse in the rehabilitation process or if possible taken directly to an area that has been reshaped.

Once the topsoil has been removed it is then necessary to blast the underlying material in order to break it down to a manageable size so that the dragline and excavators can handle the material.

Bengalla has a low stripping ratio, this means the amount of rock we have to move for each tonne of coal is less than most other mines in the Hunter Valley.  At Bengalla approximately three cubic metres of rock (overburden) will be removed in order to get one tonne of coal.  This covers our costs and also means that less equipment is needed and helps us minimise our environmental impacts.

In order to uncover the coal, waste rock is drilled, blasted and overburden dug out by a dragline.  Excavators and trucks are used to mine the coal.  Haul trucks are used to transport the coal from the mining face to a coal receival hopper which then travels by a conveyor to the coal handling and preparation plant.
 

Production and reserves

In 2006 Bengalla produced 5.54Mt of thermal coal.

At 31 December 2006, Bengalla had marketable reserves of 149.6 million tonnes (Mt).