Moving at various automated speeds, conveyors have helped increase production flows for companies in the recycling industry for decades. While they can travel as fast or as slow as programmed, the machines do not vary just by speed; conveyor size and functionality are important as well.
C&D recyclers who have incorporated conveyors into their separation systems say that their operations could work without the assistance of conveyors, but it is not ideal.
Workers at Kurtz Bros., Independence, Ohio, for example, used to spread out a load of recycled commercial and demolition byproducts—from metals, concrete and brick to roofing material, insulation and stone mixtures—by hand on the ground, says Tim Lee, industrial operations manager for Kurtz Bros., which provides products and services for the landscape and construction industries. The workers would then flip the pile of products and handpick through it all again, he says.
Since the company installed its first conveyor more than three decades ago, workers have been able to move more material at once, Lee says. Depending on the particular operation, about 25 workers monitor the nearly 30 conveyors in operation, he adds. Kurtz Bros.’ conveyors are from multiple suppliers, including Terex Corp., General Kinematics, Powerscreen and even in-house custom configurations.
“Conveyors move loads much more cost-effectively and faster,” Lee says. “They allow workers to separate out materials faster and easier as they are laid out.”
Milo Trauss, operations manager at Revolution Recovery, Philadelphia, says conveyors are vital to the recycling industry. Revolution Recovery receives C&D debris, separates it into constituent materials through a system of manual labor and automated processing equipment and produces various products for recycling, Trauss says.
The nearly 10-year-old company has 10 belt conveyors, three vibrating pan conveyors and one screw conveyor that range in manufacturers from Erin Recycling and Sparta Innovations to Doppstadt and General Kinematics.
Trauss explains that the belt conveyors transport material between machines and along a line where the material is sorted by hand. The belt conveyors also are used on magnets to toss material to the side of the machine, enabling the magnet to continuously collect.
Revolution Recovery’s three vibrating pan conveyors are used in high-impact applications and to spread out material when feeding machines, he says. The company uses the screw conveyor in its trommel screen.
These two conveyor styles aid in separation and stockpiling in a nearly seamless manner. “Vibrating pan conveyors and screw conveyors are used in screens so it is almost as if the conveyor itself is separating the material,” Trauss says.
Revolution Recovery favors rubber belt conveyors, as they have become the company’s most used conveyor configuration, he says.
“Conveyors are an integral part of recycling technology and enable processing that would otherwise not be possible,” Trauss says.
He continues, “Our operations could work without conveyors, however, conveyors enable the use of automated equipment that separate material that would not be feasible by hand.”
Feed to final
Without the use of conveyors, John Voortman, general manager of Countrywide Recycling, Hamilton, Ontario, says his company would never be able to separate 400 tons of C&D material in an eight-hour shift with 25 workers, which the company currently accomplishes.
Countrywide is an indoor recycling processor with a 60,000-square-foot material recovery facility (MRF) that specializes in the recycling of C&D material, from wood and cardboard to drywall, asphalt and aggregates including brick, granite and porcelain.
Continental Biomass Industries (CBI), Newton, N.H., built the company’s stationary system. The 4860 Grizzly Mill features 20 conveyors that are used to feed, transfer and discharge final products to various sizing machines including an Action Equipment Taper-Slot screen, an Action Equipment Dense-Out air knife separator and a trommel, Voortman explains.
Voortman says Countrywide’s conveyors are the reason the work gets done. “Without conveyors to get the product from one machine to another, then to the grinders and bunkers where the final product is stored, well you can quickly see that it would take hundreds of men to do that in a day,” he says, referring to the company’s daily 400-ton output.
Wear and tear
Because many of the C&D materials that move on conveyors are abrasive, maintenance is always a concern, Lee says. Kurtz Bros. runs brick, wood, ferrous and nonferrous metals on its conveyors “ranging from the size of a boulder to the size of a grain of sand,” he describes.
The Ohio-based company uses wear plates to reduce damage to hoppers, machine guards attempt to steer material clear of rollers and regular greasing helps to minimize deterioration, Lee says.
“However, eventually all moving parts do wear out,” Lee adds. “A conveyor can last forever; moving parts will wear out but with a thorough inspection schedule, this is minimized.”
While Kurtz Bros. has replaced various parts of its machines over the years, the company has several operating conveyors that it has used for nearly two decades.
Trauss says a conveyor structure itself can last decades, but belts will deteriorate. Revolution Recovery’s oldest belt is five years old, but the company has had some conveyor belts last only nine months, he says.
Belts weaken along the edges, and tears and seam failure are common, according to Trauss. To avoid this, proper conveyor maintenance includes ensuring belts are properly tracked, skirting needs are managed and rollers and V-plows are cleaned. Trauss says greasing can help to avoid pulley bearing failure in conveyors. On the other hand, vibrating and screw conveyors have considerably less maintenance issues, he adds.
“The life of a belt can be extended by adding splices and stapling tares with plate fasteners,” Trauss says.
If and when a conveyor’s belt does tear, Voortman says repairing it as soon as possible will give it a little more life until it needs replaced.
Since Countrywide opened in April 2011, the company has replaced four conveyor belts due to something jamming the system and tearing the belts beyond repair, Voortman says.
“The main feed belt was replaced because it was just worn out; it got the biggest abuse of all the belts because the C&D material is dropped from about 8 to 10 feet above with the excavator,” he says.
Countrywide’s excavator also is a reason the company is choosing to slow down its main feed conveyor’s speed.
The company’s conveyors move 57 feet per minute but that is too fast for the heavy equipment, Voortman says. He explains that when the excavator drops a material load onto the conveyor belt, the excavator then turns to pick up more products, which leaves large, wasted spaces with no material on the conveyor.
“The conveyor just moves too fast and by the time the excavator gets to the pick room, the line has spaces, and we do not get enough production if the pickers don’t have anything to pick,” Voortman says.
A conveyor’s speed is determined by the amount of material on the line, if there are picking stations and if it is hydraulic or electric powered, explains Lee.
Trauss says some of Revolution Recovery’s conveyors remain at a constant speed, while others, like the sort-line conveyor, are adjusted frequently.
Guards and stops
As for safety, Trauss says there are strict rules prohibiting climbing on conveyors while they are in motion, ensuring emergency stops are in place and that all power is shut off during maintenance.
Voortman says that, despite being equipped with a customized system, the company still added more guarding to protect its workers.
Lee agrees with Trauss and Voortman that proper guarding and emergency stops are necessary safety factors. He also points out that safety is always on operators’ minds. “Of course we conduct weekly safety training sessions amongst our employees as well as completing safety and training courses,” Lee says.
The author is associate editor of Construction & Demolition Recycling magazine and can be reached via email at firstname.lastname@example.org.