Dredgers and Bulldozers

Bucketwheel dredgers are used in the three brown coal open cut mines in the Latrobe Valley. They vary in size with the largest measuring nearly 200 metres in length and 50 metres in height or 12 storeys – too long to fit inside the playing field of Melbourne‟s MCG.

The dredgers are electrically powered by 22000 volts with a very long “power lead” which unrolls from the rear of the dredger as it moves forward. The large dredgers weigh over 4000 tonnes and dig 3700 tonnes of coal or overburden per hour.

The bucketwheel drops the mined coal onto an internal conveyor belt which runs the length of the dredger. At the rear of the dredger, the coal is then dropped onto the main conveyor system which carries the coal from the mine up to the raw coal bunker which is situated next to the power station.

The bucketwheel on the larger dredgers is 14 metres high and at Loy Yang, have 12 buckets per wheel. International Power Hazelwood and TRUenergy Yallourn bucketwheels contain 10 buckets. Each bucket can hold approximately 1.3 tonnes of coal or overburden.

The replacement cost of a dredger is approximately 200 to 300 million dollars and the age of the dredgers used in the mines varies from 20 years to 40 years old. It is estimated that the dredgers in use today will continue to operate for the life of the mines. At TRUenegy Yallourn, several older dredgers have been replaced by D11 Bulldozers which push the coal down the coal face onto a wide receiving platform where it is then transported by conveyor belt to the coal bunker. Each bulldozer can push close to 1000 tonnes of coal per hour.