Modern Longwall Mining
- Published: Friday, 14 September 2012 15:00
By Steve Fiscor, Editor-in-Chief
Located in southwestern Pennsylvania, CONSOL Energy’s Bailey Complex has been a world leader for many years. The complex, which consists of three mines, Bailey, Enlow Fork and BMX, and a massive state-of-the-art prep plant, produces more than 20 million tons of clean coal per year. With a $662 million investment in the new Bailey Mine Expansion (BMX), they have now set their sights on 25 million tons per year. While those numbers are impressive, the real story behind them is the company’s renewed commitment to safety.
Five years ago, CONSOL Energy launched its Absolute Zero campaign that established the company’s core values as safety, compliance and continuous improvement. Today, the safety performance of the company’s mining operations stands well above national averages. During the second quarter of 2012, the Enlow Fork mine ran exception-free while producing 2.6 million tons. Several other mines and operations have also had exception-free quarters.
How does this cultural shift in values relate to production and unit costs? CONSOL Energy’s President Nick DeIuliis (pronounced Dee-oo-lee-us) explains it best. “The Bailey Complex gets a lot of attention simply because of the sheer magnitude of the operation,” DeIuliis said. “It’s also a great reflection of where the company stands today as far as its values and priorities.” He carefully articulates the company’s core values (safety, compliance and continuous improvement) and its priorities, which are production and unit costs.
“Values are constants that stand the test of time,” DeIuliis said. “They will not change with market conditions or differ by location. Priorities change. In a soft market, costs might become more important than production, but the two will always be subsequent to our three core values.”
CONSOL Energy is the largest underground coal producer in the U.S. and has always been an industry leader, which is well-documented in the 100 Year Anniversary section appearing in this edition of Coal Age. The company pioneered many programs over the years as far as safety, mine engineering, research and development (R&D), project management, coal preparation, longwall mining, gate road development, etc.
Those efforts continue today with the same high level of enthusiasm the company has had for nearly 150 years. “During the past five years, the Bailey Complex has implemented a lot of changes and every one of those decisions were based on improving safety for our workers,” said Jimmy Brock, COO-Coal, CONSOL Energy. He cites the decision to widen all of the longwall faces, which decreases the number of panels in a district, the number of longwall moves, and the amount of development work. All of this eliminates employee exposure. Brock talks about new overland and slope conveyor systems, which have allowed the miners to seal major portions of Bailey and will allow them to eventually do the same for Enlow Fork. Similarly, these projects reduce exposure to potential hazards.
Today, the company has established an Underground Training Academy at the BMX mine, the first of its kind in the U.S., and a new communications center on the surface at its headquarters in Canonsburg, Pa. At the Bailey mine, experienced miners are working with stakeholders to test proximity detection systems and other technologies that will protect miners in the future.
CONSOL Energy’s competitors will say mining coal from the Pittsburgh No. 8 seam, which has plenty of headroom, a competent roof and manageable amounts of gas, is much easier than other parts of the country. They would also say that a complex running four longwalls should be productive. The competition would have a hard time comprehending the management and engineering skills required to execute these projects. What may surprise them is that CONSOL Energy does not compare itself with competitive coal companies. It compares itself relative to where it stands in relation to Absolute Zero.
The Bailey prep plant accepts coal from the new Bailey Crabapple slope and existing Enlow Fork slope. Soon it will take on a third stream from the BMX slope. For now, BMX is sealed from the Bailey mine and uses the old Bailey slope to bring its coal out. Bailey and Enlow Fork essentially mirror each other. They both operate two longwalls and four supporting gate development sections. The mines also have continuous miner sections developing the mains deeper into the reserves. The longwalls have 54-inch panel belts and all of the production feeds onto 84- and 72-inch main line conveyor networks.
Ventilating such a large underground network is a massive, complicated undertaking. At any one time, there may be as many as 20 fans exhausting air from ventilation or bleeder shafts. These shafts cost $10 to $15 million and generate up to 600,000 cfm. “We like to err on the safe side when it comes to ventilation—more is better than not enough,” Brock said. “We design our bleeder system where the air is flowing openly to carry away and render harmless any dust or noxious gas. There is a balance between pressure differentials and the actual amount of air needed to carry away the dust and gas. In addition to looking at the size of the gob, we also look at the efficiency of moving air through the area we have to ventilate.”
Men enter the mines by shaft elevators and most of the materials are transported through the slopes. In a shift, they can move a continuous miner from the surface to wherever it’s going using rail- and diesel-powered locomotives. Miners are already using the new Dry Ridge portal at Bailey, reducing the underground commute, which currently stands at 90 minutes round trip, to 20 minutes. Similarly, the new Pleasant Grove portal was recently completed for the Enlow Fork mine.
The new Bailey overland and slope conveyor system allowed CONSOL Energy to seal a large portion of the mine giving it a temporary advantage over Enlow Fork. Unfortunately, at the end of July, the new raw coal belts suffered a partial collapse. Prior to the problems with the Bailey raw coal feed belts, the complex was on pace to mine 20.7 million clean tons in 2012.
The BMX mine began producing in 2009 and the longwall is scheduled to start-up in late February 2014. “We are currently hiring and training BMX miners,” Brock said. “We are currently running four continuous miner units at BMX and getting ready to start a fifth. We are on schedule for the February deadline.” The BMX mine will add another 5 million clean tons. At full production in 2015, the Bailey Complex will be producing 25 to 26 million clean tons per year.
The BMX mine is a massive capital investment, even by CONSOL Energy standards. The total cost of $662 million includes upgrades to the Bailey prep plant, such as the construction of several new raw and clean coal silos, expansion of existing railroad facilities, and installation of additional raw coal material handling systems.
CONSOL Energy is also constructing a new $207 million slope and overland belt at the Enlow Fork mine. That project began in 2010 and is expected to be completed by the end of 2013. When completed, CONSOL Energy will seal 6 miles of underground belt and take six fans off line. There will be a big savings on electricity. A similar project at the Blacksville mine reduced the footprint of the mine by 24%, eliminating three fans and saving the mine more than $150,000 per year. “More importantly, with the smaller footprint, it has less risk for our employees, less exposure for violations, and it makes the mine much easier to manage,” Brock said.
The mantra among CONSOL Energy managers and miners is: safety, compliance and continuous improvement. “We meet regularly with the miners and ask them to repeat the values,” Brock said. “When they say safety is the No. 1 value, we ask them to explain that. The correct answer is safety is a way of life.”
Working during the summers while in college, Brock cut his teeth as a union miner at the Matthews mine in Tennessee. Upon graduation, he went to work for CONSOL Energy in 1980. His career path took him to the Buchanan mine, Virginia Pocahontas No. 8, Mill Creek, Humphrey, Dilworth and Robinson Run. In 2008, after the completion of a huge modernization program at Robinson Run, he was promoted to senior vice president of the northern Appalachian mines. In 2010, he was promoted to COO-Coal.
Six years ago, the U.S. coal industry entered a dark period that began with Sago and it continued to suffer one disaster after another. During this period, CONSOL CEO Brett Harvey decided enough is enough and proactively took steps to reduce accidents at the company. “What every coal miner needs to understand is that those events affect all of us,” Brock said. “It’s not just that site or that mining company, it impacts all of us.”
Harvey said safety trumps everything and started the Absolute Zero program. “A lot of us were skeptical,” Brock said. “He put the top 16 executives in a room and said ‘there’s no rank in the room, now let’s figure this out.’ We worked through it. People started to speak up and our company experienced a cultural shift in the way we do business.
“Today, we don’t do anything if it’s unsafe, we shut it down,” Brock said. “Absolute Zero is here today, it will be here tomorrow and it will still be here in 20 years.”
CONSOL Energy’s safety performance is 2.5 times better than the national average. While that is certainly respectable, they are not content because they have not reached zero. In 2007, CONSOL Energy had 7,500 employees and 226 exceptions when the Absolute Zero plan was put into play. An exception is defined as when someone receives medical treatment or they miss work related to an injury. In 2011, the company grew to 9,100 employees, while experiencing 161 exceptions. “The workforce grew and exceptions were reduced,” Brock said. “That doesn’t just happen. Cultural change requires a constant effort every day. To me, it’s the most incredible accomplishment I have seen in my career and it will only get better.”
Developing a Longwall Leader
The Bailey Complex is the flagship operation for CONSOL Energy. The company has made some major capital investments recently to widen the longwall faces, develop the BMX mine, build the Training Academy, and install the overland and slope conveyors. All of this is an effort to safely mine more than 820 million clean tons between now and 2045, explained Brock.
Widening the longwall faces to 1,500 ft was a major investment for both the Bailey and Enlow Fork mines. “It improves our lead days because it takes a greater amount of time to mine a wider panel,” Brock said. “It enhances miner safety because we do not have to move the longwall as often. In the past, we would have moved that longwall face twice a year, but now we are moving it once a year and twice on the off years. It lessens exposure to the miners because we drive less gate panels.” Over the course of seven panels, the decision eliminates one gate and 10 months of development-related mining exposure.
While changing the mine plan seemed simple enough on paper, the biggest change was with the equipment. “Wider faces require more horsepower and all of the motors and the associated equipment just continue to grow,” Brock said. “Longwall chain is a prime example. We moved from 42- to 48-mm chain on the armored face conveyor (AFC) and we are now using galvanized AFC chain, which is more durable and lessens risks associated with corrosion.” The results from this decision to widen the faces at the Bailey Complex have been so encouraging, almost every CONSOL Energy longwall face has been widened to a certain degree. The shortest of its 11 longwall faces is now 1,100 ft, with the exception of the company’s Buchanan mine in Virginia, which is running 700 ft due to geological conditions.
All of the CONSOL Energy longwall faces are high-voltage state-of-the-art units with electronic controls and controlled start technology (CST) drives. “We run bi-di, shearer-initiated systems,” Brock said. “When the shearer passes the shields, they are automatically advanced. The miners are exposed to less harm and dust—a safer procedure.” The soft starting capabilities of the CSTs place less stress on the system.
CONSOL Energy now pulls a lot of data off the longwalls and managers can monitor the data remotely. Brock can look at the amperage on the shearer and the AFC motors, cutter speed, and the tension on the AFC chain on his laptop from any location that has Internet access. He can literally watch the shields advance on any longwall.
“As technology evolved, we were at the forefront,” Brock said. “We have purchased the very best equipment from a safety and compliance standpoint. Our employees here at Bailey and everywhere else are excited about new technology and they embrace it. The Joy and Caterpillar service reps come to the mine and train the employees, who are eager to learn. The miners also provide feedback to us as far as equipment performance. Probably 90% of the improvements in safety and compliance have been the direct result of employee suggestions from safety to ergonomics to operations.”
The typical longwall panels at the Bailey Complex are 12,000-ft long and 1,500-ft wide. The shearer cuts a 42-inch web (or a 3 1/2-ft cut). The head drive is fully automated and it can push 7 1/2- to 9-ft. “We designed it so the shearer operator can take a double cut in the headgate and push up automatically,” Brock said. “As the shearer operator leaves the headgate and cuts toward the tailgate, the crew has about 80 minutes, 40 minutes to the tailgate and 40 minutes back, to advance the headgate.” The headgate operator will tram the tailpiece the full distance and then the shearer operator gains another 7 1/2- to 9-ft. This goes on all day long. In the course of a day, an 8- to 10-hour shift, a longwall would typically retreat 22 to 26 ft.
An average longwall move for CONSOL Energy takes nine days. Brock said it takes about a day to move 150 ft of equipment. “We are fortunate enough to have spare sets of shields and a panline at Enlow and some spare shields for Bailey,” Brock said. “So, as long as gate development stays on schedule, we will set most of the new longwall in place prior to the other longwall cutting out. Many of our longwall moves are simple walk-across moves. Sometimes, we have to set 100 to 150 shields. If a face has 240 shields, only setting 100 or 150 shields makes the move easier.”
They move the longwall with diesel-powered equipment. “It eliminates trolley wires and the risk of batteries grounding out,” Brock said. “We buy the very best diesel engines on the market, running Brookville locomotives with 25-ton Deutz motors manufactured by Chrysler-Daimler. They have more power and the operators love them.”
The headgate is the nerve center for the longwall, but a problematic tailgate can bring the best longwall to its knees. “Tailgate support is huge at the Bailey Complex and we do a great job with pumpable cribs,” Brock said. “We use them in the bleeders. It’s extremely important to keep that area supported because our examiners travel it weekly and it optimizes the flow of ventilation. We also have to maintain a ventilation split on the tailgate.
“Over on the headgate side, which is the tailgate for the next longwall, we set one block of can supports and then we blanket the block with 2 to 3 inches of rock dust,” Brock said. “Then, for the next longwall panel, the tailgate is fully supported and 80% rock dusted.”
A lot of supplementary support is installed for the headgate on development. Each of the intersections has 16- to 20-ft cable bolts. A cable bolt is installed in the center of the roof strap on every other row in the belt entry. The walk-side rib is meshed, which protects the headgate operator.
Brock believes automation will play a greater role in both the longwalls and the continuous miner sections. “A fully-automated face might be possible, but we would not remove the entire human element,” Brock said. “Miners would be on the face monitoring the system and there is a big difference between monitoring and operating controls. We would want to do the same thing with the roof bolting process in the sections.”
Keeping Development Ahead of the Longwalls
The Bailey mine has eight continuous miner sections. They are developing two gates for each longwall (or four total) with four miners sections cutting the mains. For the mains, they are using the Joy 12 CM full face continuous miner. In the gate development sections, they are using Joy and Sandvik continuous miners. The continuous miners are supported by Joy 10SC shuttle cars and Joy 14 BU loaders.
Each continuous miner advances 300 ft in the same entry. The operators cut coal, dump it on the ground and bolt as they advance. Behind the continuous miner, loaders gather the coal and fill the shuttle cars. The continuous miners cut coal independent of shuttle car availability.
Bailey is testing the new Sandvik MB610 continuous miners. “We have spent a lot of time working with Sandvik,” Brock said. “We sent our team to Austria to see the machine and we implemented some design changes. The technology is unbelievable. The machine is doing well. It has a fully-automated cut system. It won’t bolt hands free yet. We are pushing Sandvik on that. It has an LED display that depicts the cutterhead in the cycle as it sumps, shears down and retracts. It also has a remote camera to view the offside of the machine. This is critically important because the 610 is a bigger machine, and it enhances the operator’s vision on the offside of the machine.”
Occasionally the sections encounter soft bottoms or other adverse conditions. If the continuous miner is leaning, the miners would have to use cribbing and jacks to level it and start mining again. CONSOL Energy engineers requested Sandvik install four jacks on the machine, one on each corner. With remote control, the continuous miner operator can now lift any of the corners.
Brock also likes the stab jack. “In soft bottoms, we can advance 4 ft without using the crawler pads,” Brock said. “The cutting cycle is completed. Then the operator trams the machine forward without the stress and vibration. The cycle is repeated. Our goal is to complete that cycle in 6 minutes. Bailey has had runs of more than 300 ft per shift with that machine.”
The continuous miner section has a miner operator, a tube man (handling ventilation), two bolter operators, who are satellite bolting, and another miner behind them rib-pinning. “We are not required to by law, but we rib pin everywhere,” Brock said. Within that one 6-minute cycle, two 8- to 12-ft roof bolts are installed on the outside of the roof strap, along with two rib pins installed with a pie pan or a 4-ft T3 channel.
The continuous miner sections use a Fletcher center bolter that tilts to bolt and mesh the ribs. They also have the tilt bolters on the continuous miners. Bolters have also been mounted on the loaders. “While the shuttle car is tramming to the feeder breaker, we can install a few center bolts,” Brock said. “That’s a huge advantage. Some areas, especially when you are cutting a longwall set-up face, can be 22- to 26-ft wide. When it’s wide, we can only cut 40 ft and then we have to bolt 40 ft. With the loader, we can continue to put those bolts up. We have five of these units in operation now and we are expecting to get three more later this year.”
New Technology Underground
Discussing some of the new recent regulations, Brock explained that safety at CONSOL Energy is not driven by regulations. “We have a moral obligation to our employees,” Brock said. “That’s how we view safety. It’s a process that continues to evolve. Some of the new regulations may be burdensome, and some of them may or may not improve miner’s safety. The laws are on the books and we will comply with them. Our culture is not one where we improve safety because of new regulations. We are doing it because it’s the right thing to do for our employees.”
Nonetheless, all underground coal operators have had to contend with new regulations such as new communication systems mandated by the Miner ACT. “When the requirement for everyone to carry a radio first came out, we wondered how we would deal with this,” Brock said. “Well, we managed through it and our mines are better for it today. In addition to safety, it’s a great management tool. We can talk to any individual in the mine now using our radios. Not long ago, we would be pulling belts or moving a shearer, miners would attempt to communicate with each other with their cap lamps. Today, the operator has hand-held radio and he’s driving a machine with the very best diesel engine. They say pull forward 10 ft and he can pull forward 10 ft.”
The Bailey Complex is using a leaky feeder system with handsets and tracking devices on the miners. “It’s unbelievable how well this system is working,” Brock said. “We know where all of the miners are located all of the time.”
Proximity detection technology is currently being tested on most of the equipment at one of the sections at Bailey. “We have it on scoops, shuttle cars and loaders,” Brock said. “We want to get a system in place as soon as possible to protect our people. Unfortunately, we have discovered some issues and are workig with manufacturers to develop the safest system possible for our employees. These systems still need to be approved by MSHA.”
Proximity detection is a delicate balance, Brock explained, because “you want to give the operators room to work, but you want to protect them as well. If these systems work the way we expect, we could prevent people from entering the red zone. We would effectively engineer out mistakes made by employees.”
The Underground Mine Academy at BMX
The Bailey Complex employs 1,500 miners. According to Brock, finding miners is not difficult, finding experience miners is. CONSOL Energy finds itself training a lot of inexperienced miners. So much so that the company recently completed a $12 million underground training center at BMX, commonly referred to as the BMX Underground Mine Academy. Located right off the shaft bottom at BMX, it has fully-equipped training rooms with projectors, Internet access and computer availability. Then 600-ft away, it has an actual continuous miner section.
“Right now we are using it to train foreman, but we will eventually begin training inexperienced miners,” Brock said. “We will train six to eight miners for a week at a time. We let them operate the equipment, a shuttle car, loaders, center bolters and miners. They use the same mining methods that we use every day. They have to establish ventilation and perform all pre-op checks. It has been a huge success.”
CONSOL Energy recognized the need approximately three to four years ago when it began to experience one of the first waves of retiring Baby Boomers. “In 2007, we had 7,500 employees and today we have 9,100. We hire 1,000 to 1,500 employees a year. We are replacing people with 25 to 45 years of experience with people that have zero days of experience.”
Brock is confident in CONSOL Energy’s ability to attract miners. “We will find miners because a mining job is a good-paying job with great benefits,” Brock said. “I call it a single-household job. One parent can work while the other one takes care of the family.”