The Ensham Joint Venture - which is made up of Idemitsu Australia Resources, Bligh Coal, and Bowen Investment - has prepared its environmental impact statement for the project.

Ensham said the extension would maintaining the operational workforce of about 600 employees.

The mine is proposing a single seam, underground bord and pillar mining operations to extract thermal coal at the current planned production rate of 4.5Mtpa within existing mining leases and extending into another mining lease area.

It would use existing underground and surface infrastructure including road, rail and mine infrastructure equipment.

Ensham said there would be no extra surface infrastructure or surface disturbance within the additional mining lease area.