By Steve Fiscor, Editor-in-Chief
The Upper Ohio Valley is home to some of the most productive underground coal mining operations. Between Pittsburgh, Pa., and Morgantown, W.Va., more than a dozen longwall mines cut coal from the Pittsburgh No. 8 seam—it’s elephant country. CONSOL Energy operates a number of longwall mines in the region. The company takes great pride in its northern Appalachian reserves and has been investing heavily to upgrade production in the region. With more power plants opting to scrub, those decisions are starting to pay dividends.
One the company’s success stories is the McElroy mine. Located south of Moundsville, W.Va., the mine completed a $200 million upgrade that included a second longwall face, a revamped coal haulage network, and an increase in processing capacity. Five years later, the mine is posting production figures that sister CONSOL Energy longwall operations Bailey and Enlow Fork, which were the unrivaled leaders for many years. Mining 10 million tons per year from a mine employing two longwalls is an accomplishment.
In addition to production and productivity, McElroy is also a leader in safety. The company is experimenting with a couple of new programs to improve communications at the mine. “Our MSHA incident rate is 2.5 times better than the national average,” said David Kelly, vice president-Ohio Valley operations, CONSOL Energy.
This year the McElroy mine will celebrate 40 years in operation. The mine started producing coal during October 1969. Similar to many coal mining operations at the time, it was a room-and-pillar mine using continuous miners and shuttle cars. McElroy installed its first longwall in 1979. The second longwall began production in June 2004.
The company recently completed a transition to the new Cameron portal, which will get men and materials to the face a little more quickly. When CONSOL Energy says the new portal facility is one of the best in the company, it’s safe to say it’s one of the best in the world. Similar to most high-production longwall mines with great reserves, it also finds itself trying to stay one step ahead with panel development.
McElroy Hits Its Stride
The mining conditions in the Pittsburgh No. 8 seam in general are good and great for longwall mining. The seam height averages 6 ft and the mines routinely encounter a 1 ft split [binder] near the roof with a rider seam that gives the entries an additional 2 feet of headroom.
At current production levels with its known reserve base, McElroy will be mining for approximately 22 more years. “We are currently scheduled to run 10 to 11 million clean tons per year,” said Ken Harvey, McElroy’s general superintendent. “The mine record stands at 10.47 million clean tons and that was set three years ago .”
In mid-2001, CONSOL Energy decided to add a second longwall section to the McElroy mine. It took roughly three years to prepare the mine for the additional production. “In part of the mine, a new three-heading area was cut and a new belt line was installed doing a way with rail haulage,” Kelly said.
Using the experience it gained operating two panels at the Bailey and Enlow Fork mines, CONSOL Energy incorporated some new ideas to improve haulage and ventilation. “We have completely changed the look of the mine,” Kelly said.
Part of the mine’s secret to success is the underground bunker, which is capable of storing 7,500 raw tons. “The bunker is in a very good location,” Harvey said. “There are four conveyors inby the bunker and a total of 11 belts outby. The bunker has 17 bins and will normally feed coal out of the bunker at around 4,000 tph to keep an even flow on the outby belts.” The bunker prevents surges, metering coal consistently to the prep plant.
For development on its main entries, McElroy mines from nine headings to provide adequate ventilation (one belt entry, two track entries, three intakes and three returns). “The two track entries take track air to the face,” Kelly said. “The three intakes are the fresh air escape-way. That gives us the amount of air we need to run the mine efficiently and effectively.”
Putting in the two track system was well received by the workforce. “The miners see what we’re doing,” Harvey said. “We’re screening the roof and ribs in high travel areas for the life of the mine. The whole area is supported. We put 6-ft bolts in the roof on advance. We’re putting 12- and 16-ft cable bolts [supplemental support] on the mains. The ribs on the mains have 4- or 6-ft rib bolts. We install rib straps on advance everywhere in the mine. On the mainline section in the two track entries and the belt entry, we install plastic mesh with three-hole straps supporting the ribs.” The mine is also now lighting up the track entries.
Currently McElroy is installing a system that will feed emulsion to the longwall from the surface. “Hauling emulsion 14 miles across the mine can become time consuming especially when it can be pumped,” Kelly said. “Soon we will be able to mix it with city water on the surface which will eliminate a lot of contaminants. It makes the entire process a lot more efficient.” The mine has also upgraded the water system with dual 8-inch lines.
Underground, McElroy uses electric-powered equipment primarily, but they plan to bring diesel outby equipment underground later this year in the form of locomotives and mantrips. “We’re trying to be very forward thinking and use what we have learned at Bailey and Enlow Fork,” Kelly said. “Two years ago we would talk about what we planned to do. The miners would listen and nod their heads, but they wouldn’t believe it. Once we moved to the new portal, they quickly became believers and you could feel it.”
The Logistics of a Two Panel Mine
At a depth of 500 to 1,100 ft, McElroy operates two longwalls and six continuous miner sections. Four of the continuous miner sections are dedicated to panel development. The other two continuous miner units are driving the mains. “Normally, we pull a longwall panel in seven to eight months,” Harvey said. “The panel lengths average 12,500 ft and it takes almost a year for the continuous miner units to develop the panel.”
Both faces are high voltage (4,160 volts) and employ Joy 7LS shearing machines, 890-ton Bucyrus shields, and armored face conveyors from Longwall Associates. The longwall face lengths are 1,100 ft to 1,400 ft.
Typically, the mine schedules seven to nine days to move a longwall and get it back into production. “Most of that work is moving the shields,” Kelly said. “We will have everything else on the start line. Normally the mine will schedule three to four longwall moves a year. In fact, this year we still have three more longwall moves scheduled at McElroy.”
With a dozen longwall faces in operation company-wide, it’s safe to say CONSOL Energy knows a thing or two about longwall mining. “On a longwall move, we follow company protocol,” Harvey said. “When we get within 300 ft of the recovery area, we install supplemental cable bolts in every entry. We are usually cutting all four entries up to that point. Then we drop down to mining three entries. So the intake, belt, track, and the returns have supplemental bolting in the headings and the crosscuts.” During panel development, the continuous miner sections mine four entries until they reach a distance of 600 ft inby the recovery area, then the gate entries are developed as a three-entry system for the remaining length of the panel.
“We will clean it all up and rock dust the area thoroughly,” Kelly said. “We will have the mesh delivered in the tailgate along with Walker steels. Everything is prepared in advance and ready to go down to the battery charging stations.” McElroy uses Petito Mules to pull the shields.
The mine plan obviously hinges on panel development. “If the panel is mined out and the longwall has nowhere to go, you’re in trouble,” Kelly said. “We have made some huge strides at McElroy to get development where it needs to be. Our ultimate goal is to have at least 60 lead days for the section to finish and be able to set the longwall up. We’re getting there.”
A lot of the success on development can be attributed to scheduling. The mine uses a modified 5-2 schedule to operate around the clock. “We have four crews to run one section. The crews get two days off a week and development continues 24-7,” Harvey said.
Before the move to the Cameron portal, the mine was taking a close look at the development on the mains and realized that they were in danger of falling behind. “So we moved two of our 5-2 crews to the mains,” Kelly said. “We’re running mains seven days a week so that we can get them pushed far enough ahead of gate development and get it back to where it needs to be.”
Kelly likens development planning and execution to taking a trip. “When you go on a trip, you look at the distance and estimate the time it will take to get there,” Kelly said. “It’s the same with mining. You want to get that section started with plenty of time so that, if you hit a fault, or bad bottom or top conditions, it’s just a bump in the road.”
McElroy makes extensive use of satellite miners (or bolter-miners)—a continuous miner that can simultaneously cut coal and pin the top. McElroy uses the Sandvik (formerly Voest Alpine) satellite miner and they are testing the new Joy prototype 14ED. The continuous miner cutterhead sumps while the crawler pads remain stationery. “We do not place change,” Kelly said. “We bolt off the miners on advance. We run with a loading machine, a 100-hp fan, and two shuttle cars. We have a bolter for center bolting the entries after we mine them up. We advance on 275-ft centers with a three-entry gate development.”
The gate entry development sections at McElroy led CONSOL Energy in advancement in at least five months of 2008. The 6A panel led the company in retreat during March 2009. “On miner development we have posted some great numbers in the 7A panel development and the mains,” Kelly said.
Training the Next Generation
CONSOL Energy has a number of training centers. The company also relies on contractor groups for apprentice miners to get the time underground and to train them on the basics. Those contractors have to adhere to CONSOL Energy standards for safety, especially in regards to protective personal equipment (PPE). These contractors vulcanize belt, change belt idlers, construct arches and overcasts, and build mine seals.
Ken Harvey joined the McElroy team in January while the mine was moving the longwall out of the south area. All of the production crews were moving to the new Cameron portal and Harvey instituted several new safety initiatives that revolved around the use of technology to better communicate with the miners. “He has been instrumental in developing a new culture for safety at the mine,” Kelly said.
One of the first concepts that Harvey reinforced was that 99.2% of the McElroy employees worked safely during the first quarter. If we could just get that other 0.8% on board, he explained, McElroy could meet that Absolute Zero goal.
Company-wide as part of the Absolute Zero safety program launched by CEO Brett Harvey, CONSOL Energy, has developed a mentoring program. “The mentor—usually a top supervisor—audits the work habits and inspects near misses,” Harvey said. “They then write reports and conduct discussions on how to improve and avoid those situations. It has also had a very positive effect at the mine.”
At the Cameron portal, McElroy has satellite communications. With a feed from CNN and plasmas in the waiting areas, miners have access to news from the outside world. The mine also has the ability to record and broadcast messages which they do routinely. This was an effective tool that Ken Harvey had experimented with at other CONSOL Energy longwall mines. “Before each shift, the superintendent or mine foreman can address all of the miners before they go underground,” Harvey said. “First, they talk about safety. They review any recent accidents or near misses. They talk about the status of McElroy and other mines in the company. Then they will talk about what they want to achieve during that shift. This really works. All of the miners hear the same thing at once.”
The new communications system works especially well for safety videos. “We have a lot of people retiring,” Kelly said. “We try to catch them before they go and ask them to record a video, talking about what they have done in their careers to remain safe and what they have accomplished. When the miners see one of their buddies on the screen, they can identify with it and they pay attention. That has been a very positive program.”
With 728 hourly hands and 152 salaried staff, McElroy may have the most people working underground in the U.S. “When you talk about stretches of working safe—we had a run of 48 days recently without a reportable accident—and that speaks volumes when you have that many people underground,” Harvey said. “There are some great things happening here and we are very proud of it.”