Part of the South Blackwater complex, which was owned by QCT Resources, Kenmare’s long-term future was finalised after the BHP-Mitsubishi alliance (BMA) takeover of QCT in 2000. BMA announced that it would close both Kenmare and the Laleham bord and pillar mine; the latter closed in February this year.
Kenmare has never been able to live up to expectations largely due to difficult strata conditions. Since mining began unstable strata have severely impacted longwall mining. After a mixed fortune in the A seam, the longwall was relocated to the C seam. Conditions in the C seam proved far worse than expected and the seam workings were abandoned half way through the first block.
Mining then moved back into the A seam in the Kenmare 2 highwall mine. The original Kenmare 1 mine was sealed in early 2001.
For the remainder of the mine’s life there are two longwall blocks – 3A and 3B – yet to be mined, each containing roughly 680,000 tonnes of coal. The 3A block was commissioned in late November. The current area contains normal faults ranging from 10m-0m in displacement and thrust faults ranging from 4m-0m.
The recent longwall move took place 250m from the highwall at 80m depth. One of the challenges of moving the gear was getting the chocks out from under the weak roof with rock strengths of under 10 Mpa.
Mine manager Bruce Sherriff praised the efforts of longwall crews who have just endured over 600m of driveage with major faults present in the face at all times. Part of the risk management process was to draw cross-sections every 10m to look at the mining horizon. Despite the onerous conditions Sherriff said the crews had achieved very good face control, and an increase in productivity of around 250%. Longwall output in fault driveage has also increased from 4,000t per day to 10,000t/d.
Once Kenmare wraps up production next year the equipment will be sold at auction, probably by about June.