While the problem was anticipated by similar roof conditions in the previous two panels, in panel 18 the condition was worse than expected and resulted in delays. Tahmoor has subsequently decided to shorten panel 19 to avoid a possible reoccurrence next year.
The longwall changeover to panel 19 was completed in less than four weeks, including overhaul of the shearer and several chocks. Production resumed on October 3, and additional production shifts are being worked to recover production lost in August.
A total of 710m of underground development was completed for development of longwall panel 19, which was completed in mid-August. Since then all mine development infrastructure has been relocated to the northern part of the Tahmoor lease in preparation for development of panels 20, 21 and the Tahmoor North panels.
Drilling in preparation for development of panels 20 and 21 continued during the quarter with a total of 8688m of drilling for gas drainage completed. The in-seam drilling program has been scaled back as gas conditions in the north of the lease improved. The company said less intensive drilling is required to reduce gas concentrations to the required level which will lower costs and increase the rate of mine development from October.
Work on development of Tahmoor North accelerated with expenditure in excess of $2 million following the establishment of a project management team.
The long hole exploratory in-seam drilling program was completed by specialist contractors confirming the location of known structures and continuity of coal. As a result of this work the layout of the Tahmoor North longwall panels and scheduling of related development and gas drainage works is being amended to optimise the mine plan. A reduction in development driveage and a reduction in mining risk are expected.
A contract for underground civil works including the excavation of the main driveheads for the 4000tph north-west conveyor belt system was completed while relocating development infrastructure to the north of the lease during the changeover. Tenders for refurbishing the underground route and installation of the new conveyor are being reviewed. The conveyor will be completed by mid 2002 at a cost of approximately $8 million and will accommodate longwall production from panels 20 and 21 as well as Tahmoor North.
The company placed an order for a $3 million Joy 12CM30, to be delivered in the first quarter of 2002. Purchase of a second new continuous miner is under consideration.