Mining Coal

ENGIE owns and mines coal from the Hazelwood mine in the Latrobe Valley for its Hazelwood power station. Loy Yang B power station, also owned by ENGIE, purchases its coal supply from Loy Yang Power which operates the adjacent Loy Yang A power station and coal mine.

HAZELWOOD MINE - DREDGERS

The Hazelwood open-cut mine covers a very large area - over 1000 hectares at grass level. The perimeter of the mine is over 16 kilometres. The mine is larger than the size and depth of Uluru (Ayers Rock), although it would be a better fit if you turned the great rock upside down. The brown coal is covered by ‘overburden’ - mainly a combination of clay, gravel and top soil. This must be removed before the coal can be mined, although the top soil is reclaimed for mine rehabilitation work. The average depth of overburden is 18 metres and the average depth of the coal seam is around 100 metres.

The key to mining brown coal at Hazelwood is the bucket-wheel excavator or “dredger” - the huge digging machine that eats into the batters (walls) of the soft coal. The dredger digs and then deposits the coal on the first of many conveyor systems, which eventually transport this coal to the power station boilers.

The dredger is an enormous and powerful machine, but it is easy to overlook the fact that it is also
a precision instrument. The dredgers’ operations are guided by lasers. In fact, this was one of the world’s first applications of laser technology in the industry. Lasers provide reference for the path
of the bucketwheel and ensure that digging is efficient and minimises waste.

ENGIE has four dredgers and multiple conveyors systems on different levels in the Hazelwood mine. Three are generally scheduled to dig coal with two supplying coal to the power station and one removing the overburden material. The fourth dredger is available in case
of plant breakdown.

HAZELWOOD MINE - CONVEYORS

Each dredger supplies coal to a system of conveyor belts which carry the coal out of the mine. Over 21 kilometres of conveyors exist at Hazelwood.

The conveyor system is capable of carrying in excess of 2,000 tonnes of coal per hour. On the journey to the boiler, the coal is carried by conveyor to the slot bunker which provides reserve coal storage of up to 25,000 tonnes. Coal is used continuously from these storage bunkers to maintain
a 24 hour operation, seven days per week.

From there the coal is screened, crushed and carried up to smaller bunkers closer to the boilers. Each of these conveyor systems contains electronic weighers, electro-magnets and metal detectors to find foreign objects in the coal.

Finally the coal is pulverised into fine particles which are blown into the boiler. This allows for a rapid and very hot combustion process. Hence the process of delivering the coal fuel from the ground to the power station - and the eventual supply of electricity - has begun and continues around the clock to provide energy security for Victoria.