fuel
The Coolimba Power Project will be fuelled by a large sub-bituminous coal deposit 20km south of Eneabba, WA.
Discovered in the 1960s, the deposit was studied extensively in the late 1970s with more than 16 kilometres of diamond drilling, 50 coal quality drill holes, preliminary mining and utilisation studies completed. It was concluded that the coal was suitable for use in a baseload power station, but at the time the WA electricity market was not able to support a baseload power station in the Mid West.
A resource of 85 million tonnes has been defined by Aviva in accordance with the Joint Ore Reserve Committee (JORC) code, although the deposit is known to contain more than 150 million tonnes of coal. Recent drilling by Aviva has highlighted the potential to expand the resource.
Coal quality is largely determined by the geological rank of the deposit which is high-volatile sub-bituminous. The analysis from Aviva's recent drill program in 2005 is tabled below along with other typical domestic thermal coals used in Australia.
| proximate analysis | coolimba | hunter valley | collie | loy yang |
| Rank | Sub Bituminous | Bituminous | Sub Bituminous | Lignite |
| Analysis | As received | As received | As received | As received |
| Moisture | 28.5% | 9.5% | 26% | 62% |
| Ash | 16.3% | 24.1% | 6.5% | 2% |
| Energy | 16.2MJ/kg | 21MJ/kg | 20MJ/kg | 8.15MJ/kg |
Sources
www.dpi.nsw.gov.au
www.griffincoal.com.au
www.loyyangpower.com.au
The coal seam is over 12 kilometres in length (strike) and first occurs at a depth of 20m (subcrop) and declines at angle (dip) of 10 degrees to the east where it is still present to a depth of at least 200m. The seam is 8-9m thick and occurs in one major ply in the south and two plys separated by up to 5 metres of rock (interburden) to the North.
Weak overburden is the most important attribute of the deposit. Geotechnical studies show that the overburden removal can be effected using only bulldozers and conveyors. This has major benefits for capital and operating costs compared to most coal mines where the overburden requires drilling and blasting.
Open cut mining is planned to a depth of only 100m to extract the coal. Mining will be undertaken with a "dip-cut" method to allow for almost all of the waste to be placed back in the ground, returning the land to its original contour.