Minor roof condition problems, gas levels and commissioning of new equipment all conspired to slow advancement rates from Tahmoor North’s panel 22.
The mine produced 187,000 tonnes of run-of-mine (ROM) coal during the quarter, down on 2003 output.
Commissioning and testing of the new longwall system and associated equipment began at the end of May, however operations were discontinuous as engineers worked to commission the new equipment.
The longwall advanced relatively slowly during the month cutting 74 metres of the panel, yielding 94,000 ROM tonnes.
Slow advance rate impacted roof conditions, resulting in minor stone falls across the face. Austral said the falls did not cause a problem for the new equipment.
Due to the stop-start operations longwall operators cut into the floor to provide additional working height while commissioning was underway – reducing recovery of clean coal.
Gas, mainly CO2, emanating from the longwall face during operations had been higher than expected by Austral, contributing to slow mining progress.
“Elevated gas levels were expected in the initial part of panel 22 until the longwall advances through a dyke system that runs diagonally across the panel in its first 600 metres. Gas has been well drained in the latter section of the panel,” said Austral.
Quarterly development reached 3,802 metres, equaling 93,000 ROM tonnes.
Austral said the two Tahmoor development units had been relocated and engaged in advancing the 800 panel mainroads and completing the installation heading for panel 23.
At the end of the quarter one unit had begun driving the 803 gateroads for panel 23. The company said the favourable mining conditions had resulted in much improved development rates.
The three Roche contract development units had been relocated and engaged in mainroad development in the 900 panel area. Roche has now completed more than 50% of its development contract.
A third Tahmoor unit is expected to commence mining in July and a tender has been awarded to Joy Manufacturing for the manufacture and supply of a fourth 12CM30 continuous miner for delivery late in the year, completing the upgrade of the mine’s CM fleet.
Upgrade of the mine power supply was completed during the quarter, with the installation of 11KV surface substation and transformer, new high voltage reticulation underground for the longwall and a new longwall electrical system.
Work continued on major conveyor belt installations in the 900 panel mainroad and 903 panel longwall conveyor for the next panel. Stage one of the upgrade of the drift and surface conveyor systems in underway with preliminary designs approved.
Expenditure on exploration and mine development during the quarter was A$16.926 million.
Tahmoor’s workforce successfully negotiated a new bonus plan during the quarter, which was introduced in June.
Austral shares dropped 7c during trading yesterday to a low of 69c before recovering slightly to close at 71c.
