Production of coal has commenced at Rio Tinto's $2 billion Kestrel mine extension in central Queensland.

Rio Tinto says the new extension will likely add another two decades of productive lifespan to the Kestrel coal mine, situated 40 kilometres north of Emerald in the state of Queensland.

The extension is set to reach full production within the next two months, while overseas shipments are scheduled to begin in the next several weeks. It will reach full capacity by the end of 2014, and is expected to have an output of around 5.7 million tonnes per annum on average during its operation life.

Kestrel has been in production since 1999, and is at present the diversified mining giant’s only underground coal operation.

The extension for Kestrel obtained approval in 2007, with construction commencing towards the end of 2009.

Kestrel mine manager John Coughlan said the commencement of production on the extension was a major landmark for the coal mine.

“After four years of construction, seeing the longwall cutting coal is an exciting milestone and marks the start of a long future for Kestrel mine,” he said. “We process high quality coking coal for export using the longwall method and expect to see our first shipment from this new area of the mine leave Australia in the coming weeks.”

Coughlan also said completion of the extension will finally permit a transition from the Kestrel mine’s current zones of production to new, untapped territory.

“Over the coming year and a half we’ll see a gradual transition of production as our existing operation, known as Kestrel North, winds down, and the new Kestrel South operation ramps up,” he said.

The use of the longwall method – which involves the mining of a single long tranche of an underground mine – for the  extension necessitated the construction of an eight-kilometre overland conveyor, which is capable of delivering over 3,500 tonnes of coal per hour.

Rio is also using the EL3000 Caterpillar longwall miner for the extension, which can cut around 5,000 tonnes per hour.