Tearing It Up

Designs and features of shredders and grinders that contribute to efficiency and profit

Rotochopper’s 75DK shredder/grinder hard at work
Rotochopper’s 75DK shredder/grinder hard at work

With any type of waste-stream, the initial demand is for size reduction. However, perhaps more important is the matter of turning waste material into value for profit. “It depends on what the customer is trying to achieve,” explains Dale Walker, technical sales engineer, Weima America Inc., “but waste-to-energy is 95% of what we do. We recover fuel. Fuel is a cost per ton.” Reducing volume is 5% of what they do, he adds.

Recycling plants make a product, sometimes shredding wood to produce mulch and save on hauling costs. MRFs make a product, shredding internal waste to make a new product (often fuel) and avert material from the landfill. Some facilities focus on product destruction so they can throw it away. Whatever the end product, Walker says, the main goal is always to get the most for the least.

To withstand streams that can include metal, concrete, and other “ungrindable” materials, a shredder must be durable. Low-speed, high-torque functionality enables a shredder to avoid catastrophic failures when impacting such materials, says Jamey Brick, COO, Rotochopper, adding that “the hydraulic pressure is designed to monitor for ‘unshreddable’ material and backs up the rotor when this type of material is detected.”

Rotochopper offers three high-performance shredders from Lindner that provide additional capacity to generate revenue, according to Tosh Brinkerhoff, president and CEO:

  • The 95DK (770 hp) for high volume
  • The 75DK (330 hp) for lower volume
  • The Atlas 5500 stationary unit with an electric motor, ideal for robotic sorting downstream

Their shredders are diversified, allowing them to handle most types of waste, including mattresses, carpet, furniture, railroad ties, and other difficult materials, Brinkerhoff explains. For residential and commercial waste, he says a good shredder is sufficient, but for construction and wood waste, he suggests adding a grinder.

Rotochopper’s 30 years of experience in the C&D and wood waste markets benefit the recycling industry because their shredders contribute to generating revenue in two ways, Brinkerhoff says. Recyclers can charge higher inbound tipping fees for contaminated waste and they will have more outbound material to sell. “The investment in a high-performance shredder will quickly pay for itself by keeping ‘ungrindable’ objects out of your high-speed grinder.”

Shredding waste with Metso’s M&J K160Shredding waste with Metso’s M&J K160Metso

Because many wastestreams are so diversified, having a shredder that can handle a variety of materials is valuable. ARJES slow-speed shredders, from the German company ARJES GmbH and offered by Bandit Industries Inc., are built to handle a wide variety of common waste, from industrial and urban waste to metal waste and even concrete, says Craig Davis, sales manager.

The Impaktor 250 and the VZ950 Titan are suitable for municipalities and waste management companies that deal with construction and wood waste. The VZ950 Titan is ARJES’ largest, most powerful slow-speed shredder. Featuring a 700 hp Volvo Tier 4f engine and a 318-cubic-foot infeed hopper, the Titan is capable of shredding anything from wood to metal waste, with production rates up to 177 tons per hour.

The Impaktor 250 is one of the most versatile slow-speed shredders on the market. Davis says no other shredder can match its performance at this size and price point. A single machine can grind, crush, and shred concrete, rubble, asphalt, bricks, ceramic, metal, wood, and waste. Special shaft geometry positions the material to be crushed, then secondary double jawbreakers, in conjunction with the breaker bars, help operators achieve a more consistent final product size.

Pronar trommels sort and size material as it moves through a wide barrel screen, and Pronar stackers can speedily move material and build towering piles. Pronar trommels and hydraulic stackers by Pronar SP are designed to work rapidly, sorting and moving material to keep up with the fast-paced materials processing industry. “Pronar machines are built to move material quickly,” confirms Davis. “Adding a Pronar trommel and hydraulic stacker to an operation can improve your operational efficiency drastically.”

Bandit Marketing Manager Pete Jennings concludes that “owners can expect rugged, durable machines that are ready to handle the toughest jobs.”

Shredding waste with Metso’s M&J K160Shredding waste with Metso’s M&J K160Metso

Tough jobs are the norm with MSW. “Shredding for MSW must be able to cope with any type of contaminates [or] ‘un-shreddable’ materials,” states Hartmut Bendfeldt, president of eFACTOR3 LLC. He says all Metso pre-shredders, regardless of the size, can shred any type of waste: carpet, MSW, C&D, paper rolls, metal, bulky waste, mattresses, furniture, carpet, and bales of film.

The Metso M&J K series of waste pre-shredders begins with the M&J K160 and M&J K210, both of which provide a low cost per ton with high reliability, ease of operation, and a design optimized for sites with a 5- to 45-tons-per-hour production requirement. The open cutting table design means operators do not need to pre-sort the waste being loaded into the shredder because un-shreddables can pass through.

The unique design of the Metso open table allows foreign matter like glass and other abrasive material to fall through the machine without creating a lot of wear, he continues. The open cutting table features 3-inch-wide blades and a 6-inch-wide comb, but because there’s no edge-to-edge cutting, heavy-wear items fall through.

Rotochopper’s 75DK takes on wood waste.Rotochopper’s 75DK takes on wood waste.Rotochopper

The final shred size is determined by the amount of cutting discs and the table opening. The application determines the exact configuration of the shredder and the desired hourly capacity, and the final cut size determines the size of the shredder.

Metso primary shredders come in various sizes that can process anywhere from 45 to 150 tons per hour. They are used in a mobile configuration in landfills to create a homogenous fraction that is easier to compact and could increase the actual density in the landfill. They are also used in RDF facilities to create a homogenous fuel instead of Hammermills. “This solution cuts down on the risk of explosions from propane tanks since the machines are high-torque, slow-speed machines,” explains Bendfeldt.

However, the secondary shredder can only process a “cleaned-up” fraction of MSW since they are not designed to cope with heavy contaminates. Secondary shredders re-shred the material after it has gone through the typical steps of pre-shredding, screening, sifting, magnets, eddy current, and optical sorters. “The final product is typically used as an alternative fuel in the cement industry,” points out Bendfeldt, “or for gasification and pyrolysis systems.”

If the waste needs to be processed into an alternative fuel that is used as a coal substitute in pellet form or as a loose fuel in the cement industry, Metso offers the 1550, 3550, or 6500 shredders as secondary shredders to achieve particle sizes from 1/2 an inch to 4 inches. These are single- or double-shaft machines that do the final shred after a sorting line removes contaminate from the stream, Bendfeldt explains.

The shredder is also well-suited for MRF operations since they produce a homogenous output that ensures even distribution on the downstream sorting equipment for better recovery.

Because this machine ensures that all bags are opened, utilizing it at the beginning of the sorting line makes it easier to create clean commodities.

CBI’s 6400CT Horizontal Grinder chewing up logsCBI’s 6400CT Horizontal Grinder chewing up logsCBI

Horizontal and tub grinders from Morbark can process various types of waste. Both are used in the waste reduction process and can take wastestreams from waste to wanted material by grinding it into a mulch that can be sold in multiple markets including mulch, compost, and renewable energy, according to Michael Stanton, director of industrial products. “Determining the type of consistent feedstock and the desired end product is the key when identifying the right type and model of equipment.”

Morbark offers multiple hammer patterns and screen sizes to meet various end-product requirements. Where the material may have light contamination, such as nails, bolts, or truss hangers, the magnetized end pulley removes these ferrous metal contaminants during the processing phase.

Continental Biomass Industries, a Terex company, introduced its 6400CT Horizontal Grinder and Chipper at the 2019 Factory Forum in Newton, NH, where it processed steel-contaminated railroad ties and a mix of C&D debris to promote the range of environmental equipment at the show.

The 6400CT is an extreme-duty, fully welded horizontal grinder that can handle contaminated C&D, RR ties, pallets, storm debris, shingles, whole trees, and logs, thanks in part to its larger, more durable shaft and bearing assembly.

Its cassette-style clamshell design allows users to swap out rotors quickly to shift from grinding to chipping, which enables acceptance of jobs with multiple material demands. “Operators can go from grinding to chipping in half the time as before,” according to Morbark. Four interchangeable rotors enhance its versatility.

CBI’s clam-shell design allows for a quick swap out of rotors.CBI’s clam-shell design allows for a quick swap out of rotors.CBI

Additional features include an offset helix rotor to distribute material evenly across the rotor and a sloped hydraulic filter to shed materials. Speed sensors provide a continuous pace.

“The 6400CT [is] an excellent machine for customers who demand productivity, reliability, and versatility,” says George Wilcox, director of sales and marketing at CBI & Ecotec – Americas.

Choosing the right shredder and grinder can improve efficiency and profitability by increasing the speed of processing materials and producing cleaner, more usable end products. 

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