Anglo Coal Australia acting CEO Neville Sneddon said the new equipment would increase productivity as future longwall reserves, estimated to be in excess of 100 million tonnes, increase in depth from 250m to more than 400m.

Moranbah North has dealt with a number of safety issues over the past year, including a series of dangerous roof falls and a fatality in April.

Following one of the incidents in September 2006, a safety report found inadequate roof support had been installed to control the geological conditions in that area of the mine.

“The higher capacity powered roof support system (PRS) will provide significantly improved roof control and employee working conditions while mining Moranbah North’s remaining longwall reserves,” Sneddon said.

Each of the new Joy PRS units has a nominal yield load rating of 1750t and uses two 480mm internal diameter leg cylinders. The centre spacing between adjacent supports is 2050mm rather than the current 1756mm.

Sneddon said the Joy PRS units will undergo a rigorous testing program to 90,000 cycles to provide confidence in a 45,000 to 65,000 cycle life.

“These powered roof supports will be the most powerful and largest supports that have been designed for the global market and represent a significant step forward in roof support technology,” he said.

Apart from absolute capacity and the testing program, other engineering improvements being used include base side shift cylinders, electronic canopy anti-tilt control, and improved side-shield performance.

Design work, construction and installation of the new longwall system are expected to take about 18 months.

Moranbah North is owned by Anglo Coal Australia in a joint venture with several Japanese resource companies.