Based on the earlier example, if your mine is only achieving equivalent run time of 800 hours, the benefits of learning from Mine USA are clear. Massive strata, laminated roof, seam gas and spontaneous combustion in various combinations may be contributing to the gap between performances. Allowing for these can reduce the “hurdle rate” for “Mine USA equivalent performance”
Again, simplistically, if your mine is losing 100 hours of production per year due to gas trips, and Mine USA has none, there is still scope for improvement at your mine based on the other practices of Mine USA (such as hot seat changes or maintenance programs).
It may be the case that when all conditions are allowed for, your mine’s performance is already “Mine USA equivalent”. If this is the case, then you should be looking closer at your own operation instead of worrying about external comparisons.
Identify the areas with the most scope for gain. Does gas cause more downtime, or roof falls? Should the gas drainage layout be revised, or could improved monitoring of strata behavior help to understand and avoid the problems associated with heavy weighting?
As one operational colleague of mine used to quote: “Every minute that the longwall is down costs us $1000.” Detailed operational reviews allow management to be proactive in addressing productivity improvement, focusing on those areas with the most potential. And who knows, by picking the right areas to target, the Laser may one day overtake the Commodore.
* Glenn Everett is a senior mining engineer based at Australian Mining Consultants’ Brisbane office. He visited several mines in the US in 2000 (including Twentymile and Enlow Fork) and has analysed production and delay data provided by some of the mines. AMC provides integrated technical and business solutions for all levels of the mining industry.
Originally published in the March 2001 edition of Australia's Longwalls.