Published in the December 2008 Coal USA Magazine
The mine is operated by Speed Mining, a holding of Magnum Coal, which was purchased by Patriot Coal earlier this year. Despite several letterhead changes in a short period of time, the mine has continued to stay its course in a crucial time when most operations would be tripped up by personnel changes, management adjustments and other side-effects of consolidation.
The mine, which at 500-1400 feet of overburden is slightly deeper than its southern West Virginia counterparts, began mining in April 2000. The longwall took coal from its first panel in December 2001.
The environment underground, at standing height, is comfortable for the average worker. The Eagle seam here is 46-53 inches but mining thickness is 66-84in in development sections and 69in average at the longwall face. No coal is left behind and, according to management, the overall geology is favorable.
“In the north area of the mine the immediate roof was generally sandstone. As we progress into the southern portion of the mine, we transition into an immediate roof of primarily shale,” general manager Doug Fala said.
The orientation of the future panels in the south is such that it is most ideal for the reserve’s horizontal stresses. The northern area, which the longwall is currently mining in, includes an area of conditions that are adverse for longwall extraction. The coal seam, he explained, pinches out a bit in this region but the immediate roof and floor are also comprised of extremely hard sandstone – a perfect storm for issues – though the previous and current panels have run right through the heart of it.
“In [this] area of adverse cutting, cutting speeds are dramatically decreased and the wear on critical equipment is drastically increased,” he explained.
The trip to American Eagle’s longwall takes about 30 minutes using one of the mine’s fleet of Brookville mantrips on track haulage. The current panel and the next one to come are fairly long and wide by US longwall standards at 16,000ft by 1200ft. Its south reserves are projected slightly shorter at 10,00ft by 1000ft.
Pulling coal from the longwall face is a Joy 7LS1A shearer with a 45in web with installed power of 4160 volts. Providing support above crew’s heads are a collection of Bucyrus 2-leg shields, each with a 1290-ton capacity and working range of 47-87in, that are PM4 computer controlled.
“We currently have a number of extra shields that we rotate between panels for rebuilds and major repairs,” Fala said of the operation’s plan for maintaining uptime. “Currently [we] have two shearers that get rebuilt and rotated between panels.”
He added that the mine also used two complete face conveyors.
Ventilation is yet another area where management has devoted much concentration. While gas is not an issue at American Eagle, its circuit utilizes a push/pull system with two blowing fans and two exhausting fans with a fifth small fan that only ventilates a set of seals. The system moves approximately 500,000 cubic feet per minute through the mine, officials noted.
Once the coal is pulled from the face, the work of its Bucyrus PF5 face conveyor begins. It features 48mm Thiele face chain running at 375ft/minute powered by triple 1200hp motors that run to a 60in mainline belt. Conveyor belt drives and structure throughout the entire infrastructure are provided by Continental Conveyor. The majority of the conveyor rubber is provided by Fenner Dunlop.
Fala said there were no major obstacles in the belt system’s production capacity. “All mainline belts that the longwall is dumping on are in great shape equipment wise with fully vulcanized belt rubber,” he said.
“[A] long-term project is to replace the rubber in our south belt system and get it completely vulcanized prior to the longwall mining in that area of the mine. We are also updating the electrics on a couple of our belt drives in the South area and installing TPKL couplings on these drives.”
American Eagle’s crews also make a science of progress along its single longwall panel. A normal month on the current configuration will see retreat of 50-55ft daily to produce an average of 12,000-13,000 clean tons per day.
With longwall mining now several years old at the mine, the staff has become accustomed to move planning. All departments take part in the logistics, incorporating best practices from prior moves to help improve the next one.
A typical longwall move takes 7-10 days. When pulling out of the panel, crews utilize basic bolting across the tear down face with 6ft torque tension bolts.
Aside from the longwall at American Eagle, there are two active continuous miner sections mining a three-entry gate development system and six entry submains. Coal is extracted using walk-between super sections, and the fleet includes two Joy continuous miners, three Joy 10SC32 shuttle cars and two Fletcher Roof Ranger II roof bolters.
Support at the sections includes standard 6ft torque tension bolts with a typical 4ft by 4ft spacing. It also utilizes supplemental support with DSI/Dwyidag truss bolts for both longwall headgate entries and areas of the mine that have adverse conditions.
As coal from the development sections is extracted, it is carried on the mine’s continuous miner section belt systems, which consists of 42in structure and belt rubber running on 48in belt drives. Management at the mine has made standard process of maintenance as well. Its dedicated crew, for example, follows a schedule of routine oil samples and component tracking of major equipment.
“Maintenance is performed on the longwall during weekends,” Fala said.
He added that a three-man maintenance crew is also assigned to each CM section to complete preventive maintenance on the owl shift daily. Equipment is standardized as much as practical to other machines within the company without sacrificing mine specific needs.
Although at times productivity has been affected by geologic conditions, the American Eagle mine is considered a highly productive operation by regional and national standards. It does so with a modest crew of 145 employees and 48 staff at the preparation facility. Of that total, 137 men spend their days underground.
“[A] longwall production crew consists of...click here to read on.
