Dendrobium coal mine sees second roof fall

BHP Billiton's Dendrobium underground coal mine has seen its second roof fall in two years.

The roof collapse occurred in the main tunnel of the Dendrobium mine last month, with the New South Wales Trade and Investment Department confirming that an eight metre thick section caved in, the ABC reports.

The Department stated that no one was injured or trapped in the incident, but workers further down the mine had to use alternate exits to escape.

Since then the miner has changed the way in which its roof supports are monitored.

It was the second time this has occurred in as many years, with a section of roof 14 metres long and five metres thick falling on an access road in November 2010.

No one was injured at the time.

However, earlier this year a man in his 40s lost three fingers in an incident at the coal mine.

The miner lost his thumb, ring, and pinky fingers after they became trapped between a coal tram and the mine's face.