The Carborough Downs underground operation in Queensland produces metallurgical coal (hard coking coal) and pulverized coal injection coal for the export steelmaking market. When the mine commenced operation in August 2004, it was a bord and pillar operation with two continuous miners. In 2009, a $400 million expansion converted Carborough Downs to a modern long wall operation with an average mining rate of 3.5 million tonnes per annum (run-of-mine) to yield about 2.8Mtpa of product coal. The Leichhardt Seam, which is mined by the long wall, is relatively uniform and ranges from 4.5 metres to 5.7m thick, with total resources estimated at between 280Mt and 300Mt.
For the first quarter of 2011 Vale reported that although Carborough Downs completed a long wall move in the fourth quarter of 2010, production was negatively affected not only by the adverse weather, but also by geotechnical conditions of mining in a steep profile of the coal seam, which caused some roof falls. Production for the quarter ended September 30, 2011 reported that coal production has been lower than that produced during the second quarter of 2011, due to geological problems with a rock fault encountered during mining, which resulted in lower coal yields with a high percentage of rock in run-of-mine.
Operating. The mine was due to reach its nominal capacity of 4.8Mtpa during 2011.