Published in May 2005 American Longwall Magazine
The mine is operated by Cumberland Coal Resources, an affiliate of Foundation Coal. Located about 12 miles south of Waynesburg, Cumberland is one of two neighboring longwall mines that make up the company’s Pennsylvania business unit. The Emerald longwall mine, operated by Emerald Coal Resources, lies immediately adjacent to Cumberland. Both mines operate in the 6-8ft thick Pittsburgh No.8 Seam.
Cumberland is currently mining a two-mile long, 1250-foot wide longwall panel. Early last year, ventilating the previous 1040ft super-panel at face start-up was difficult, resulting in the mine being idled in February. Since production resumed in May, it has been full steam ahead for the northern Appalachian mine.
In March, Cumberland came close to breaking its monthly production record with an output of 722,000 tons clean coal (809,000t overall).
The mine made history in 2002 when it became the first operation to install DBT-supplied 2m-wide roof supports after the prototype was released at the 2000 MINExpo show.
A Joy 7LS2 shearer incorporating 545hp ranging arms completes the face equipment. The DBT face conveyor is driven by a 350hp motor; electrical controls are supplied by Service Machine.
A new set of DBT face conveyor pans (PF5) are on order and will be delivered in October for installation. The order also includes 100 additional DBT roof supports.
The Joy shearer achieves a single pass in around 40ft per minute. Conventional bi-directional cutting with a snake at both ends is used at a web thickness of 42in.
Coal feeds onto a 60in section belt then onto a 72in main belt and finally onto a 48in slope belt to the surface. The capacity of the coal preparation plant was upgraded to 1500 tons per hour.
The mine’s rated capacity is around 6.7 million tons high Btu, medium sulfur coal per annum, primarily supplied to eastern power utilities.
Maintenance is a substantial focus at the operation and involves a regime of both preventive and predictive maintenance using a range of techniques such as visual checking and oil sampling.
Maintenance is conducted during a one and a half hour interval every two days with an extended four-hour idle time set aside on Tuesday and Thursday every week. A longwall maintenance planner oversees maintenance schedules assisted by three maintenance foremen, one working each shift.
Preventive maintenance involves scheduled changes of filters on shields, shearer and the pump station giving a longwall face availability typically around 98%.
The Joy 7LS2 shearer is rebuilt every panel under contract to the OEM while the Kamat pumps are also rebuilt every panel by the mine’s engineering department. Shearer drums and other critical components are usually changed out mid-panel. Each panel contains roughly 5.9Mt and wear is high on parts such as the stage-loader and head drive sprockets and rack wheels on the shearer sprocket.
“We know we will wear out the haulage sprockets on the shearer about mid-panel,” said maintenance foreman Randy Conklin. “When we change these out we also look at the stage-loader chain and if need be will change that out, too.”
Roadway development mining is scheduled to move to the new western area in about three years time and until then development will continue to focus on getting roadways developed for the mine’s remaining panels.
Development performance is assessed daily, weekly, monthly and quarterly, and averages 90ft per shift.
“Our rates come up well within our projections,” said mine manager John Dzurino. “Longwall development over here is not like one of these mines that doesn’t have a longwall and is strictly continuous miner [CM] – they’ll mine up to 200ft per shift. But they don’t do anything to establish a longwall. Extras like installing monorail clips, we hang our belt, put in a lot of rib bolting, do Tensaring on belt entries … everything’s geared to the longwall.
“In fact, we don’t even consider our CMs as production units; it’s all construction and set-up work.”
Cumberland’s CM units typically produce around 25,000t a month.
Pre-drainage drilling is currently conducted ahead of mining by drilling contractor Target Drilling. Horizontal longhole drilling has been used at Cumberland since 1996 to improve gas extraction ahead of mining.
Gas produced during drilling is either diluted in the mine atmosphere or piped to a vertical borehole that vents the gas.
The ageing workforce is an issue at all mines in the US. Cumberland sometimes picks up “black hats”, or experienced miners, from mines that are shut down in neighboring areas or other states.
Maintenance manager Tony Fiem bemoaned a lack of qualified supervisors and maintenance personnel.
“We as a coal industry need to invest in training programs for maintenance personnel,” he said.
“We need young people with a technical degree and knowledge of electronics because it is very hard to learn how to troubleshoot underground when you are in a crisis situation. One of the ways we are addressing this problem is through a joint program with Westmoreland Community College to develop a new mechanics training curriculum as well as a curriculum for advanced and refresher training for existing mechanics.”
The mine’s workforce is represented by the United Mine Workers of America. On a weekly basis, some 18.5 shifts run per week. This includes 2.8 by nine-hour shifts a day for five days and 2.5 by nine-hour shifts Saturday and Sunday.
