Pinnacle mine breaks world record for plow production
Cliffs Natural Resources’ Pinnacle underground coal operation in West Virginia, USA, has experienced a number of firsts.
- It was the first longwall operation in the United States to use a plow rather than themore common shearer for its primary production machine.
- In 1989, it implemented the world’s first fully automated plows, eliminating the need for an operator at the face.
- In 2012, with a new state-of-the-art longwall plow system manufactured by Bucyrus (now owned by Caterpillar Inc.), the mine became the first to produce 29 400 tonnes (32,400 tons) in a 24-hour period — a world record.
- In 2013, those plows became the first to be rebuilt by Cat® dealer Carter Machinery after the dealership took on the support of the former Bucyrus products purchased by Caterpillar in 2011.
- And in 2014, this mine claimed another first — producing 32 400 tonnes (35,700 tons) and breaking its own world record for production.
Mining the Pocahontas seam
Pinnacle mine is wholly owned by Cliffs, a major supplier of low volatile metallurgical coal used worldwide to produce the highest quality metallurgical coke for the steel, merchant coke and foundry coke industries. It is also used as a blast furnace injection product in steelmaking.
Cliffs’ North American coal reserves are some of the largest high-quality metallurgical reserves in the United States. Cliffs owns and operates two metallurgical coal operations in West Virginia and Alabama. Its Pinnacle Complex, made up of the Pinnacle and Green Ridge mines, as well as the Pinnacle Preparation Plant, has a rated annual capacity of 3.6 million tonnes (4.0 million tons). Pinnacle mine’s 2013 production totaled 2.5 million tonnes (2.8 million tons).
The Pinnacle coal mine lies in southwestern West Virginia, near the city of Pineville, and coal is mined from the Pocahontas #3 seam. This seam lies at a depth between 300 and 500 meters (984 and 1,650 feet) and has an average thickness of 1.4 meters (54 inches). All mine activities are in horizontal deposits, with an inclination of less than 5 degrees.
Coal has been mined at the Pinnacle site (formerly U.S. Steel #50) since 1969; since 1977, scores of panels have been mined using roof-fall exploitation with plows and roof supports. Faces are extracted using the retreat mining system. Initially, four parallel entries were prepared on each side of the face, resulting in very high heading costs. The number of entries was later reduced to three to enable timely preparation of the entries for the next panel, an issue because of the high mining speeds of the plow system. For this reason, transport and conveyance were located in a common entry. The entries at Pinnacle have a height of approximately 1.8 meters (70 inches). Only the main transport and conveyance entries have a height of 2 meters (79 inches). Initially, coal was transported to the surface by rail carriages, but a central belt conveyor was later installed.
The mine complex employs about 550 workers and estimates a total annual economic impact on the region of US$193 million, with US$20.4 million of that amount being its contribution to state and local taxes.
Plowing instead of shearing
A number of factors make the Pinnacle mine unique, but one of the most notable is the site’s decision to use longwall plows rather than shearers. While plows are slowly becoming the system of choice for longwall mining in seams with an average height under 1.8 meters (70 inches), Pinnacle was the first to adopt this method in 1977 and today — nearly 40 years later — remains the only longwall mine in the United States to use a longwall plow.
“While many mines around the world embrace the use of plows, all of the longwall systems in the United States use shearers,” says Rodney Mowles, mining operations manager at Carter Machinery. “But Pinnacle felt decades ago that with the blocks of coal they have, and the height of their seams, a plow better suited their needs. They still believe that today.”
The plow used in 1977, though, was vastly different than the modern machines of the last few decades. In the late 1980s, the mine decided to build on the success it had with early plows and purchase a new system that incorporated the latest technologies. The two longwall plow systems delivered to the mine in 1989 and 1990 by Westfalia Lünen of Germany (a predecessor of Bucyrus/Caterpillar), were the world’s first fully automated plows.
As Pinnacle continued to successfully produce, updates were made to that system — including a new plow guide in 1991, a new armored face conveyor (AFC) drive system called Controlled Start Transmission (CST) in 1994, and a new plow body in 1995. In 1999, an additional fully automated plow system was installed. Over the years, plow power increased from 2 x 270 kW (362 hp) to 2 x 400 kW (536 hp), then to 2 x 600 kW (800 hp).
After more than 10 years of very intense mining activity, the Pinnacle mine decided to purchase a completely new longwall system. A comprehensive study of available technologies was undertaken to select the most reliable and efficient system and ensure the lowest possible production costs. After a very detailed analysis, Cliffs decided to stay with what was working and purchase a new plow system — still manufactured in Lünen, Germany, but this time by Bucyrus, which would become part of Caterpillar less than two years later.
In July 2010, the system was assembled and extensively tested in Houston, Pennsylvania, a Bucyrus room and pillar equipment manufacturing facility in the same region as Pinnacle, before being set up, tested and screened on site that same year.
The GH1600 plow system has 2 x 600/300 kW (2 x 800/400 hp) of installed power for the plow, with two operating speeds of 2.0/1.0 meters per second (395/197 feet per minute) and 2 x 600 kW (2 x 800 hp) installed power for the AFC. Each roof support in the system has a total leg cylinder capacity of 649 tonnes (715 tons) with an operating height range of 890 to 1968 millimeters (35 to 77.5 inches) and is equipped with its own PMC-R electrohydraulic roof support control. Other units from the Cat Programmable Mining Control family are used for overall face automation and visualization, as well as for drive control. The longwall is equipped with a PF4/1132 face conveyor, a PF4/1542 stageloader and a SB0815 V-belt crusher with a 225 kW (300 hp) motor.
Keeping production moving
In order to ensure peak productivity from its longwall system, Pinnacle follows a strict preventive maintenance plan for the GH1600 plows. “We take the plow down for two hours every day for maintenance,” says Tyler Davis, Cliffs’ longwall manager, who is responsible for the Pinnacle site.
Underground mines typically perform this type of maintenance themselves, and Pinnacle is no exception. Mine personnel take care of equipment on a daily basis, relying on the manufacturer for parts and support when specific expertise is required — such as troubleshooting problems, maintaining automation or other complicated technologies, and performing major activities like machine rebuilds.
Carter Machinery has provided maintenance and support for equipment on the surface side of the Pinnacle operation for a number of years. “An underground coal operation requires construction on the surface,” says Scott Looney, Carter mining area manager. “The infrastructure must be in place to process, load and ship the coal, and we maintain the Cat equipment they use in the process.” Surface equipment includes Cat D10 and D9 dozers and 988B and 980 wheel loaders.
“As we were coming on board with the Bucyrus responsibility, we sat down with the managers of Pinnacle,” says Mowles. “We talked through the surface side, where we do most of the wrench-turning. We’re trying to work with them and get a similar relationship with the underground operation. Right now they do their own repairs, and we help by providing technical information. We work remotely as well as go underground with them to figure things out together.”
Because the plows are automated, computers are an essential component. One employee sits in a control box, where he operates the plow and roof supports remotely through a computer system. At the same time, Carter technicians are able to access and troubleshoot this equipment from the surface if needed.
“Our technicians have access to the computer systems from above ground,” says Mowles. “They can sit at home and see how the plow is operating. We can take readings and fix problems without ever leaving the computer.” This work is supported by technical service representatives who go underground to get a firsthand look at the equipment, and then communicate it back to the surface. “Yes, the computer can tell us a lot, but we also rely on having someone see it in person,” Mowles says.
Enabling continuous production
With two plow systems that are designed for more efficient movement from face to face, and support equipment on hand to prepare the site, Pinnacle mine is able to begin mining on a new face almost immediately after the previous one is completed. Continuous miners, including two Cat CM340s, dig out entryways and get the faces ready for the longwall. While one panel is being mined, the next is being prepared to keep production moving.
At about 2590 meters (8,500 feet) long, each panel takes between seven and nine months to plow. While one plow is hard at work, the other is getting maintained and prepared for the next panel. That preparation typically requires a complete rebuild of the machine.
In the past, rebuilds of the GH1600s were done by the plow’s manufacturer. With the Caterpillar purchase of Bucyrus, that process became the responsibility of Carter Machinery. Carter took over the Bucyrus business just weeks before the first rebuild was scheduled. Mowles admits it was a challenging time.
While personnel at the prep plant have been partnering with Carter for decades, those responsible for the mine’s underground operations were not familiar with the dealer. “We hadn’t even met most of the underground mine people,” says Looney. “We hadn’t had an opportunity to build their confidence in what we can do.”
Pinnacle finished mining a panel in June 2013 and the plow was scheduled to be put back to work in January 2014. The mine worked so efficiently, though, that they got ahead of schedule — which meant they would be ready to start mining another panel in October.
While the urgency put additional pressure on Carter, delaying the mine’s production was never an option, says Looney. “We had to move faster than we expected, but we knew we had to stay on their schedule. Even though preparation delayed the new panel until December, we had it ready to go in October.”
Getting up to speed
The Carter team recognizes and understands that Pinnacle viewed the rebuild with a bit of apprehension. “Of course there was some hesitation on Pinnacle’s part,” says Mowles. “The plow is essential to their productivity. They can’t have it going down in the middle of the cycle. We knew that we couldn’t let that happen. We had to get the rebuild done on time, and the machine had to be ready to run for as long as it took to mine that next panel.”
While Carter took over responsibility for Bucyrus equipment just weeks before the Pinnacle plow rebuild, the dealership had been preparing for that day for many months. Mowles credits the Caterpillar integration team for making the process as comprehensive as possible.
“Caterpillar committed to doing anything and everything to train dealerships to handle this type of process,” says Mowles. The Caterpillar facility in Houston, Pennsylvania, was on call to answer questions anytime. Carter personnel visited the facility on a number of occasions to watch rebuilds in progress. Carter technicians were sent to work alongside them, and former Bucyrus employees joined the Carter team to ensure a seamless transition.
“I’m working with many of the same technicians we’ve always worked with but now they work for the Cat dealer,” says Davis. “They continue making the service calls. However, now they are more available to us, and parts and knowledge are also easily accessible.”
Carter found Caterpillar’s support during the transition invaluable. “One of the best things I’ve ever seen Caterpillar do was this integration process,” says Mowles. “They helped in every way they could.”
In addition, Carter personnel learned as much as they could on site, visiting the Pinnacle underground mine while the plow was in operation. “We wanted to watch it in action, see how they use it, understand how it works,” says Looney.
Completing the rebuild
The longwall rebuild encompassed a complete rebuild of the GH1600 Plow headgate and tailgate armored face conveyor drive, the headgate and tailgate special AFC pans, the stageloader drives and return end, the complete crusher, and all gearboxes for the plow, AFC and stageloader.
At the same time, Carter was able to solve some ongoing problems the mine had had with the plow. “We wanted to address these issues together,” says Davis. “So in addition to doing the rebuild, the Carter team was diligent about finding a fix for these problems. Some of them were very minor, but they were a big deal to the dealer. They wanted it to be right.”
Davis was pleased with the overall process as well as the outcome of the rebuild. “It went really well,” he says. “They do a good rebuild.”
Delivering additional advantages
While Pinnacle hadn’t considered its previous plow maintenance process a challenge, the mine has begun to appreciate additional benefits that partnering with a Cat dealer can deliver.
More personalized attention is a key advantage. “We’re seeing that our mining customers find our partnership approach and personalized service a welcome change from what they were used to,” says Mowles. “It’s a real differentiator for those sites that were accustomed to dealing directly with equipment manufacturers.”
The dealership’s proximity to the mine helps in that effort. With a branch fewer than 5 kilometers (3 miles) from the mine, support is literally just minutes away. “The longwall manager passes by our store on the way to work,” says Looney. “It’s a great convenience to the customer. They can stop in and check on their equipment and ask questions.”
In addition, the location where the rebuilds take place is just 48 kilometers (30 miles) from the mine. With previous rebuilds, the plow would have to be hauled to Pennsylvania — over 400 kilometers (250 miles) away.
“Pinnacle made multiple visits to see the rebuild in progress,” says Looney. “Some were announced and some were not. And we were OK with that. We want to be their partner. We want them to feel comfortable stopping in.”
Being on site during parts of the rebuild helped Pinnacle personnel become more comfortable with the process. “They saw our equipment, our tools, our facility,” says Looney. “That helped a lot.”
Mowles stresses that the connection customers have with the manufacturer is not lost by the dealer model. “We have a large voice with Caterpillar,” he says. “So the fear that mine sites lose the ability to reach the manufacturer is unfounded. In fact, the opposite is true. We understand our customers’ issues and carry that message back to Caterpillar. And they listen to us.”
Setting records and earning respect
While there was some hesitation on Pinnacle’s part when Carter performed its first rebuild, the end result was an overwhelming success. In fact, just a few months after putting the plow back to work, the mine broke its own world record for production.
In a 24-hour period on April 10 and 11, 2014, the Pinnacle longwall produced 32 411 tonnes (35,724 tons) at a seam height of just 1.42 meters (56 inches) along the 298-meter (980-foot) longwall face. The previous record of 29 423 tonnes (32,430 tons) was set by Pinnacle in August 2012.
“Caterpillar congratulates the Pinnacle team for this great achievement,” says Denise Johnson, president of Caterpillar’s Material Handling and Underground division. “Without their efforts and dedication this record would not have been possible. To safely deliver that kind of output from such a thin seam is remarkable. We have been privileged to work alongside their team.”
To set the new record, the cutting depth was calibrated to cut 140 millimeters (5.5 inches) at a speed of 2.0 meters per second (197 feet per minute) while traveling toward the headgate, and 250 millimeters (9.8 inches) traveling at 1.0 meter per second (395 feet per minute) to the tailgate. The depths and speeds are customizable and were selected to optimize loading of the face conveyor.
Davis gives credit to the maintenance team for its role in setting the production record. “You have to have the plow up and running or nothing will be happening,” says Davis. “That’s why we are so diligent about our two-hour preventive maintenance downtime each day. On the day we set the record, we felt confident skipping that two hours and ran the plow 24 hours without stopping. If we would not have been so diligent in our maintenance practices, we would not have broken the record.”
Pinnacle recognizes the role both its own maintenance team and the technicians from Carter play in the overall success of the underground operation.
“We have a really good relationship,” says Davis. “Whatever time I call them, if I am having an issue in the middle of the night, I can call any of them. They will fix it remotely if possible, or they will come right down. Carter has made my life a little more pain-free,” says Davis. “My headaches are less with them on board.”
Caterpillar, too, gives Carter credit for stepping up into its new role. “Supporting and rebuilding a longwall plow system was a new experience for the Carter service team,” says Chris Curfman, president of the Caterpillar Global Mining sales and support division. “However, given the record production results attained by the rebuilt system at Pinnacle, it’s obvious that they are up to the challenge of supporting the underground product lines at the same high standards and quality level that they have been delivering for many years on the traditional Cat surface mining products.”
From Carter’s perspective, the customer’s success is its own success. “Our goal is to maintain equipment, perform rebuilds, whatever we’re doing, to please our customers,” says Mowles. “If we fail in any manner, then we’re a failure. That’s how we build our reputation.”