Sept/Oct 2010

Cutting a niche in a tough market

The Bucyrus automated longwall plow arrives in North America

By Alexandra Lopez-Pacheco

Cliffs Resources currently uses the longwall plow at its Pinnacle mine in W. Virginia. Bucyrus hopes to carve a deeper niche in the North American market | Photo courtesy of Bucyrus

For years, Bucyrus International, Inc. has known it had developed cutting-edge longwall automated plow systems capable of outperforming the system typically used today in longwall coal mining: the shearer. Here, the company believed, was the future of low-to-medium seam coal mining — offering tremendous improvements in everything from safety to productivity, cost-effectiveness and environmental responsibility. On the international market, many agreed; the company’s plow systems — one for extremely thin seams, one for thin-to-medium seams and another for extremely hard coal — operate in China, Czech Republic, Germany, Kazakhstan, US, Mexico, Poland, Ukraine and Russia. But back home, in North America, the South Milwaukee, Wisconsin-based Bucyrus hit a stone wall when it came to generating more market interest and acceptance.

“In North America there’s a mind block,” says Keith O’Neil, director of product management, longwall product group, Bucyrus International Inc. “There are still people in the industry who view plows as being unproductive, not powerful enough, all based on experiences from back in the 1970s when we didn’t have all the automation, the power that we do today. So they have a false perception that the plow still cannot compete with a shearing machine. And that’s absolutely not the case. We have completely reinvented the plow using today’s technology. We’re now able to produce systems that can rival and actually exceed the productivity capabilities of shearing machines in low and even medium seams up to 71 inches in height.”

An informed, contrary decision

This past July, however, Cliffs Natural Resources, an international mining and natural resources company, joined Bucyrus in a noteworthy announcement that could just mark the beginning of the end of that North American mind block. After exhaustive analysis, Cliffs had selected Bucyrus’ plow system for its Pinnacle coal mine near Pineville, West Virginia. The plow is not new to Cliffs. For decades, the Pinnacle mine was the only one in the U.S. — and only one of two in all of North America — that operated a longwall plow system; albeit one it had developed with partners in Germany that was far more efficient than the stereotypical plow most in the North American coal industry imagine. But when it came time to update its equipment, Cliffs seriously considered switching to a shearer.

“When we started this selection process back in 2007, there were a lot of people looking at the reserves who said we may need to switch to a shearer,” says Russell Combs, Pinnacle Mine’s general manager. “We were very close to making the decision to go to a shearer but we decided to back up and take a look at a few things.”

One of the first things Cliffs considered was safety. The plow is operated remotely, requiring no operators at the face. “With today’s automation technology, the plow is a very safe system,” says Combs. “The shearer requires that you have people going back and forth with it. There’s a lot of dust generation, rock that can fall in and come over on the folk. In a shearer, there are a lot of moving parts, so you have to be very diligent with your safety lockouts. With a plow, you’re able to use sprays that follow it along for dust suppression. And you don’t have electric motors and other electrical components on the plow itself; those are at the ends where there are people in controlled conditions to monitor the gasses. With a shearer, there are electrical cables and motors right on that shearer that keep moving back and forth all the time so you do have the potential for gas accumulation that could ignite with an electrical current. In a plow, you have some electricity that goes across on the shields but it’s not moving back and forth all the time. It’s safer.”

In the past, the performance of conventional plows was often compromised by variations in coal hardness, which led to different cutting depths, resulting in overloading of the conveyor and downstream equipment or jamming of the plow. Because the Bucyrus system is based on incremental plowing, it is able to avoid these complications.

“The plow works great on our site,” says Combs. “It follows the seam without manually having to control exactly where it is mining. With this plow, you just set it up, and it will go up and down with the seam. It follows the seam very well to keep us with a good clean product, not taking the rock. It will mine as much or more coal, certainly more in lower seams but as much in the higher seams as a shearer.”

A cleaner cut

Historically, plows often lacked the horsepower to proceed when they encountered extremely hard-cutting conditions. The resulting manual intervention and slowdown in production was one of the reasons the industry turned to the shearer, which has the horsepower to cut rock — and cut rock in abundance it does. This means the rock has to be removed from the coal in the preparation process, energy has to be used in moving it and eventually all that rock has to go somewhere.

“What’s happening is that with the regulatory agencies gaining more and more influence over issues like rock impoundment, reject piles, refuse piles — the whole nine yards in terms of environmental impact — the cost of preparation of coal, not only the preparation cost itself in terms of washing the coal but also the disposal of the reject, is becoming a major expense,” says O’Neil.

The horsepower in today’s Bucyrus plowing systems exceeds the specific energy that a like-sized shearer can deliver, says O’Neil, explaining that the plow basically works as a slicer attached to a continuous loop chain up to 42 mm in diameter that allows as much as 2,160 horsepower to be put into the cutting action. That means that the powerful Bucyrus longwall plows permit far more precision, minimizing reject material, resulting in energy cost-savings both in the mining process as well as in the preparation of the product.

“With the shearer, it was going to be such that we might not have enough room for storing rock in our impoundment area for the life of the mine,” says Combs. “And right now, there’s a lot of concern about the storage and new areas and where do you store this rock properly to not affect streams and such. So environmentally, this was a good choice for us also. With this system, they’ve cleaned up a lot of things. It’s very modular in changing parts, very ergonomic for getting up and down the conveyer, more room, no protrusions hanging down so you can quickly move across the face without a lot of obstructions. It’s a lot of really good technology.”

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