Clearing wetlands and a highway, Prairie Eagle’s new overland conveyor transports coal 4 miles from the new portal to the prep plant.

Two new Illinois Basin installations were engineered for high-performance

by steve fiscor, editor

Successful coal operators know the importance of well-designed conveyor systems. They also know the risks. Conveyors after all are the arterial system for underground mines. They deliver raw coal to the surface and, equally important, they clear coal from the face allowing the sections to achieve full production.

Conveyors also present a fair share of headaches. Anyone who has spliced a belt or replaced a wiper knows that it’s most often a thankless job with considerable pressure to bring production back online as quickly as possible. Ultimately, the goal is to prevent conveyor operating and maintenance costs from eating away at the bottom line of profitability.

One way to eliminate many of those variables is to replace several flights with one long conveyor. This usually requires a substantial investment in better belting, hardware, drives and control systems. Possible pitfalls to this approach can be eliminated with engineering work on the front-end and the payoffs could be a game changer. Two recent examples demonstrate how Illinois Basin coal operators are using this knowledge and experience to their advantage.

Knight Hawk’s New Overland

Knight Hawk’s Prairie Eagle mine recently commissioned a 4-mile overland conveyor. What distinguishes this system from other long overland conveyors is that it has five horizontal curves. Development at Prairie Eagle had advanced to the point where the mine needed to open a new portal. Transitioning to the overland allowed them to eliminate miles of underground conveyors as they moved away from the old portal located near the prep plant.

As they prepared to make this move, Knight Hawk investigated all the options available to them. They eventually settled on a curved conveyor system from Beumer. “The original RFQ called for four separate conveyors with three transfer points between each flight,” said Brad Williams, vice president, sales and business development for Beumer’s Conveying & Loading Division. “We suggested one long overland conveyor with horizontal curves.”

Beumer’s scope of work was mechanical and electrical design, fabrication and supply of all materials, installation, and commissioning of the system. “We worked with an installation partner that subcontracted to us,” Williams said. “We supervised their crews and then brought in our own commissioning team.”

The end goal was to move coal from the new portal to the prep plant 4 miles away. A portal belt transports coal to a stacking tube on the surface that forms a raw coal stockpile. A reclaim belt below that stockpile would feed the overland conveyor. While the overland would encounter little elevation change, approximately 90 ft in 4 miles, it would have to wind its way to the prep plant.

“Beumer has installed several long, curved conveyors in North America and this one would have five horizontal curves in it,” Williams said. “Eliminating three transfer points and the associated dust along with the potential for plugging and the subsequent cleanup would significantly reduce operating and maintenance costs. That’s why this was such a huge advantage for them.”

One of the five horizontal curves are shown at the top of the photo.

This would be quite a departure for Knight Hawk away from traditional straight short flights. Everyone’s always a little gun shy about something new, Williams explained. “We had to convince them of the system’s capabilities and, to their credit, they were open minded and acknowledged the advantages,” Williams said. “That’s the biggest challenge to implementing a system like this. It would be a big investment and it was the lifeblood for their plant. If it goes down, the entire operation goes down.”

To prepare for the decision, Beumer laid out the entire conveyor in 3D. “We flew a drone over the plant and property to collect all of the topography,” Williams said. “In doing that, we could tell them exactly to the cubic foot how much dirt they needed to pull away and fill. Using drones on these projects has really helped us with engineering and, of course, a picture is worth a thousand words. During project development, we were able to show them the entire route of the conveyor and how it would cross the highway, how it was going to cross the wetlands, and they were able to visualize it, which built a great deal of confidence.”

Knight Hawk did their due diligence and thoroughly evaluated the system, carefully weighing their options. Once they saw the potential advantages, not only with cost, but with ease of operations, they decided to proceed.

A horizontally curved conveyor requires quite a bit of engineering and Beumer has extensive experience in this area. They installed the first horizontally curved conveyor in 1971. “We have decades of experience,” Williams said. “The key is the angle of the idlers. When we install the system, we know exactly how each idler should be angled around the curve. When we commission a system, the belt trains automatically. Some mines spend weeks training traditional conveyors after they commission them. Our engineers spend a considerable amount of time looking at the tensions around the curve and the angle of the idlers so that the belt banks correctly.”

Knight Hawk’s 42-in. Horizontal Curve Conveyor System is rated for 1,500 tons per hour (tph) of minus 8-in. raw coal, running at 890 ft per minute. The abrasion-resistant, steel-cord belting was supplied by REMA Tip Top. It uses four 400-hp bevel helical gear-drive units supplied by Siemens and Flender Corp. Three of the drives are located at the head-end and one at the tail-end. The system has a hydraulic winch take-up station near the discharge end of the overland conveyor. Variable frequency drives (VFDs) allow for smooth starting and speed adjustment.

The VFDs let Knight Hawk control the speed and capacity of the system. “They were using dozers and loaders to work the piles on the feed and discharge ends,” Williams said. “They have it dialed-in to the point where they have eliminated that equipment on both ends. The coal comes out of the mine and feeds on to the overland perfectly and discharges into the plant at the ideal capacity 4 miles away.”

The tensions are so high on a system like this that we almost always use a steel cord belt, Williams explained. “We also use belt turnovers to ensure that the clean side of the belt is always touching the idlers,” Williams said. “We install turnovers near the ends of the conveyor so the material does not fall off as it travels over the idlers.”

Engineers spend a considerable amount of time looking at the tensions around the curve and the angle of the idlers so that the belt banks correctly.

One thing that helped put Knight Hawk’s mind at ease was the data collection system that allows them and Beumer to monitor all aspects of the overland conveyor. Knowing that we would be available to monitor the system remotely gave them a sense of security, Williams explained.

Since commissioning last summer, there have been no issues with the system, Williams said. “Overall, it’s a maintenance-free system,” Williams said. “They drive the belt once a day to make sure it’s operating correctly. The only transfer points are at the tail and the head.”

“More importantly, they are very happy with the conveyor and that makes the entire project worthwhile,” Williams said. “There was some apprehension until it was actually operating. The fact that we were able to commission it in a couple of days was impressive.”

The system was commissioned in less than 12 months from receipt of order. Beumer’s initial use of drone technology and 3D engineering of the conveyor route were a big factor in expediting the engineering and supply of the system.

One of the Strongest Belts in North America

Over a four-week period this past spring, Fenner Dunlop successfully carried out one of the most challenging projects of its kind. The project involved the design, manufacture, delivery and installation of one of the strongest steel cord reinforced belts in North America.

Miners splice a 72-in. Dynaflight ST7000.

An Illinois-based coal mining operator’s system requirements were for belting specifications that were somewhat unique for coal operations. Industry veteran Jerry Lovitz, executive sales manager for Fenner Dunlop, met that challenge head on, making company history with the manufacture, splicing and installation of the Dynaflight ST7000. The 72-in.-wide Dynaflight ST7000 included 1/2-in. DB x 3/8-in. Fireboss SAR covers with Fenner Dunlop’s Dynabreaker and rip detection loops weighing in at 84.5 lb/ft. That’s a total endless weight of 800,000 lb.

Using a single plane of carefully constructed, pre-tensioned steel cords, Fenner Dunlop Dynaflight belting is designed to withstand some of the most demanding applications imaginable. What sets this project apart from others in the industry is the Fenner Dunlop-patented Dynabreaker carcass technology used in the ST7000. It has a unique fabric construction derived from Fenner Dunlop’s UsFlex technology that has outstanding resistance to ripping, tearing and impact. The combination essentially created a steel-reinforced UsFlex belt composite providing unbeatable durability for mining applications.

In combination with the high-performance abrasion-resistant covers of Fire Boss SAR with grade 1 physical properties, the belt that the Fenner Dunlop engineers created is one of the safest, strongest and most durable conveyor belts available in the mining world today. The four-stage splice design was created by the Fenner Dunlop technical team, led by Akiko Wakatsuki, senior manager, applications engineering and conveyor belt standards. In total, the ultra-efficient splice design measured 20-ft long.

Winders with more than 1 million ft-lb of torque lower the belting down the slope.

Months before the job was scheduled, Fenner Dunlop delivered the new rolls of steel cable belting to the Illinois site for staging. The installation project was headed by Ted Trenney, Fenner Dunlop senior operations manager, Northern Appalachia. A veteran of countless installations, Trenney laid out a meticulous plan with the customer and the team of technicians and supervisors that would execute the job. The preparations included the coordination of some of the largest and most sophisticated belt service equipment in the world. This included two winders from the Fenner Dunlop fleet that measure at more than 1 million ft-lb of torque and two frame-style vulcanizing presses covering the required 20-ft splice.

Belt technicians were sourced from four separate Fenner Dunlop service operations to complete this pro-
ject safely and on time. Fenner Dunlop operates an internal network of factory trained and certified belting technicians located around North America. This group is responsible for installations and splicing of Fenner Dunlop belting across the country with six full-service operations. Even though Fenner Dunlop Conveyor Services has a reputation for tackling some of the toughest belt installation and splicing projects in the industry, this project was still immensely challenging.

The belt was spliced and lapped out into one, continuous 9,500 ft length.

The belt was spliced and lapped out into one, continuous length of 9,500 ft in preparation for installation. Working around the clock, splicing and lapping of the belt took place over 10 days. The team of experienced Fenner Dunlop technicians took on the huge task of laying the uniquely engineered, four-stage splice design provided by the technical experts. Unlike many belt change-outs, the sheer weight of the existing belt required it be removed in three sections prior to the installation of the new Fenner Dunlop belt. At this point, the torque produced by the Fenner Dunlop winders came in quite handy. The winders, being used in a hold-back position, coupled with multiple sets of pneumatic brakes, lowered the new belt down the slope conveyor to receive the final splice at the tail.

Thanks to the hard work, dedication and attention to detail delivered by the entire Fenner team, this project was completed safely and successfully. “Our customer asked for a solution and Fenner Dunlop delivered a seamless transition from old belt to new belt without interrupting normal operations,” Lovitz said. “In an extremely demanding and complex application, Fenner Dunlop designed, manufactured, delivered and installed one of the strongest belts in North America.”