Newlands assesses production hourly against pre-negotiated internal benchmarks. “We sat the guys down and said ‘given a perfect hour in the day how many metres could you cut?’,” said longwall superintendent (previously development super), Andy Mifflin. “We came to the consensus that in a good hour we could do 6m. In a 10-hour shift, therefore, we should be able to do 60m, but we never get a perfect shift. We said ‘well hang on, if we get a shift where we lost two hours and got eight hours of perfect conditions then we should still be doing 48m’.”
Viewing each productive day as a set of discreet blocks of time enables both management and operators to “zoom in” on delays, on a minute-by-minute basis. “Even if we had a four-hour delay we benchmark hourly against ourselves and we can see what we achieved the rest of the shift,” Mifflin said.
Not only are reaction times to delays faster but feedback to operators is virtually constant, which functions as a subtle motivator; simple but effective psychology.
The attention given to development management and systems underlines the philosophical attitude that not everything revolves around longwall production.
“Historically in longwall operations if you need extra resources to add numbers to the longwall for changeouts, for example, you pull them off development. We don’t do that,” said mine manager, Alan Payne. “Development has clear ownership of the areas they are mining. Instead of treating them like the poorer second cousin they know they are equally important to production.”
Similarly, maintenance at Newlands is conducted somewhat differently from many other longwall operations. Instead of conducting routine maintenance over weekends, when crucial OEM staffing is typically light and overtaxed, Newlands has daily maintenance windows between 7-11am Monday to Friday. Dave Caulton, the mine’s engineering and maintenance superintendent, said the system meant the mine was not dependent on who was available on weekends. The mine operates weekends on 12-hour shifts without maintenance windows. Output levels on Saturday and Sunday have been as high as 42,919t.
Systems availability on the longwall averages 75%, according to Caulton, while machinery availability is more than 95%.
On the planning front, Newlands has taken care not to get into the same trouble as it did in late 1998 when block S4 was found to be unmineable because of the presence of an undetected fault. “The accepted technology of the day, surface to seam boreholes, did not pick up the fault which ran the full length of block S4,” said planning manager, Paul Harrington. The 1.8km block was subsequently sterilised after only 271m of retreat.
After the experience of that hard lesson, Newlands is today a leading proponent of the use of 3D and 2D seismic technologies in predicting sub-surface strata. Brisbane-based Velseis recently conducted a seismic program over 5sq.km of the northern part of the lease.
Harrington said the results showed “every roll, every fault, every change in grade”. Seismic had fundamentally changed the way planning was carried out at Newlands, he added.
Mining of new block S1 began in late February and by Easter the longwall is expected to run into the Cattlegrid fault. Early and precise detection of the fault by seismic will enable rapid implementation of surface to seam cement injection to pre-support the faulted area. Apart from identifying the precise location of the fault seismic also delineated its dimensions which allowed pre-supporting to be rigorously implemented — ultimately more cost-effective, if successful.
Another spin-off from the 3D has fed into the conveyor design. “Because we could see where the seam dipped we were also able to go to our conveyor manufacturer and select the correct horsepower,” Harrington said. “We know our drive head capacity is right for the seam dip.”
The seismic data has also been innovatively incorporated into the mine’s gas drainage program. Harrington believes seismic may in time lend itself to a range of other applications, such as predicting ash content. But he warns not all mines will get the results Newlands is getting, particularly if overburden interferes with seismic readings.
Despite an extraordinary year, Newlands management and employees are acutely aware of the need to develop consistency. In longwall mining a good year can so easily disintegrate.
Electrician Aram Drake feels the mine’s main challenge will be to keep employees as enthusiastic and motivated as they are now.