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Copy and Paste This Permanent Link:http://www.mswmanagement.com/july-august-2009/grinders-shredders-equipment.aspx

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Photo: Bandit Industries

Land clearing is slow, observes Tim Wenger, president and sales manager for CW Mill Equipment Co. Inc. in Sabetha, KS, because it’s tied to the housing and construction industries that have been adversely affected by the recession. At its peak, mulch is a three-month season, he says. Even storm cleanup demand isn’t what it was a few years ago when Hurricane Katrina raged. “There are more grinders than work,” he laments. “Fuel prices are up, work is slow.”

In response to the economic downturn, besides traditional applications such as mulch and landscaping, grinders and shredders are finding new markets, particularly in the energy industry. In some instances, the traditional can be combined with the trendy. Wenger cites a California orchard that grinds up 5% of its trees annually, now sending the product to biomass power plants in order to convert it into fuel.

Producing green energy from biomass has the potential to become a very large market in this country if the draft Renewable Electricity Standard and carbon cap and trade legislation are passed, states Cody Peterson, recycling product line manager for Peterson Pacific Corp. in Eugene, OR. Introduced in the senate in February by Senator Tom Udall of New Mexico, the Renewable Electricity Standard bill requires that 25% of the electricity generated by suppliers come from renewable sources by 2025. It establishes a system of credits that suppliers can earn by producing renewable energy. The standard is expected to create more than 100,000 jobs, save consumers money, and reduce the emission of pollutants that contribute to global warming.

Photo: SSI Shredding Systems With low-speed, high-torque technology, SSI shredders process a broad range of materials with low dust, low noise, and low operating costs.

“Green” processes and recycling are driving the industry, believes Ed Donovan, general manager of Continental Biomass Industries in Newton, NH. It’s already happening; the largest recycling system is an $8 million one in Adelaide, Australia. Thanks to stimulus money in this country, he says, there are opportunities to explore alternate fuels. “There’s so much material, and it has energy value—Btu values—if you get the rock and steel out. It’s cheaper than natural gas, with clean emissions.”

Return to Roots
The green angle isn’t new. “Grinders came out of agriculture for hay bales,” Wenger relates. “In the 1980s, people wanted to try to divert woodwaste and greenwaste from landfills; the tub grinder developed out of agriculture to divert that material from landfills. Now, we get calls for the original heavy-duty grinders for making energy from switchgrass.”

Pat Crawford, vice president of product development for Diamond Z, Caldwell, ID, has also noticed the resurgence of agriculture-related usage and the need for MSW solid waste conversion. Biofuel has placed greater demand on mulch, so people are turning to new materials, he says. “They’re processing switchgrass and corn and there are new straw applications for biofuel.”

There are also more familiar applications. High-speed grinders are the primary machines used to reduce industrial woodwaste and forestry biomass for boiler fuel, Peterson indicates. “The fuel specification will vary with the type of boiler. A common boiler fuel specification is 3-inches minus with minimum fines and over-length material. A low-ash, clean product is preferred.” He advises adjusting the grinding variables (feed speed, grinding speed, grate configuration, and bit type) to make the highest-quality boiler fuel.

Peterson’s 47 series grinders (700–765 horsepower) are high-production, midsize machines for compost, mulch, and biomass application. They also switch from wood reduction to shingle grinding. For easier transport without over-width and over-weight permits, however, the 27 series (450–580 horsepower) performs the same tasks. “The 2710 series track grinder is especially suited to grinding forestry biomass where frequent moves are required.”

Another track-mounted grinder that doesn’t require super load permits is the 5710C (925–1,050 horsepower). Peterson says it’s better for land-clearing, high-volume mulch, compost, and biomass grinding applications. Diamond Z also has a high-capacity, low-maintenance model suitable for large-scale woodwaste and land-clearing operations: the DZH 7000 Series horizontal grinder, with 1,200 horsepower and 30 hammers at 140 pounds.

Peterson acknowledges that track grinders cost more than wheeled machines, but says the mobility advantage gives them an economic edge and improves loading efficiency. Donovan agrees, adding, “The most expensive part of processing is trucking. You want to get them out quickly.” He contends that track-mounted grinders can load in as little as nine to 12 minutes, as opposed to 20 minutes for wheel-mounted machinery. “They adjust to load trucks easier.” That’s why 90% of the requests CBI fields are for track-mounted equipment. However, he cautions that the “magic number” for mobility is 80,000 pounds.

Back to the Land
Despite the trend of expanding recycling for energy production, Donovan contends that land clearing, while down, remains a big part of the business. But land clearing doesn’t necessarily pave the way for construction. Wenger notes that the government is cleaning up forests in British Columbia and Alberta due to pine beetle infestation.

Photo: West Salem Machinery West Salem builds 15 sizes of grinders to fit a wide range of applications.

Photo: CW Mill The TC series HogZillas are designed for high production and tough application.

Whatever the goal, Wenger says tub grinders work well in tested markets such as land clearing and mulch, also offering the versatility to grind stumps and logs at sites such as the California orchard and Canadian forests.

CW Mill manufactures 11 standard HogZilla models ranging from midsize to “massive,” including self-propelled track-drive and self-loading units. The TC series tub grinders, available in four different models including the most popular TCII-1564P, are designed for the highest production rates in the toughest applications, thanks to a torque converter drive that allows the engine to perform at peak efficiency with multiplied torque.

Advertised as the only genuine torque converter in the industry, it allows the engine to avoid lugging and racing, helping it maintain a steady speed throughout its work cycle, regardless of load requirements. “We pioneered it,” Wenger insists, “to get away from the dry clutch” with its “repair hassles” and to protect the engine from torsional shock.

Another advantage of the TC series grinders is the patented and proprietary adjustable swing-hammermill assembly that can be changed to a variety of different swing diameters while in the field, facilitating easy customization to meet specific needs. Wenger points out that this versatility provides fuel savings and enhances productivity and resale value.

Smart tub technology developed 15 to 20 years ago from its salt spreader monitors hammermill speed. Equipped to face extreme conditions, the TC grinders feature a clog- and leak-resistant radiator with a large radiator precleaner to prefilter dirt and contaminants. Engine intake air is ducted from ahead of the radiator inside the precleaner to capture the cleanest, coolest air available. The engine exhaust assembly is configured with a special cover to keep chips out of the engine enclosure and material away from the exhaust heat.

To meet the needs of large-scale production for industrial grinding operations, CW Mill uses heavy-duty components. The grinders may be heavy-duty, Wenger says, but they’re light enough to move, even if most are in stationary facilities. Less mobile are the electric-powered grinders, made more popular due to high diesel prices as well as their increased reliability.

Versatility Adapts to Market Demands
Switchgrass and straw aren’t the only unusual materials being shredded these days. For added versatility, Wenger says some people are adapting the equipment to grind tires and are in fact doing so in Brownville, TX, where once-buried tires were beginning to come up through the ground. CW Mill sold a grinder to a company there to help it dispose of tires. “Tire grinding and shredding has become a niche market.”

That innovation is exactly what SSI Shredding Systems Inc. in Wilsonville, OR, thrives on. For nearly 30 years, says Terri Ward, systems sales, SSI has successfully adapted to shifts in market demands. “While the worldwide economy has slowed, emphasis continues to be placed on environmental stewardship and sustainability. This means we continue to see strong demand for shredders that address a variety of energy-from-waste, waste management, and recycling applications.”

SSI designs and manufactures multiple lines of low-speed, high-torque equipment. Its product lines include Pri-Max high-capacity primary reducers, twin-shaft DualShear shredders, four-shaft Quad shredders and single-shaft Uni-Shear rotary grinders, with production capacities ranging from 1 to more than 150 tons per hour. Stationary, over-the-road, track-mounted, and skid-mounted configurations are available.

Ward reports recent developments in high-performance drives that can deliver 15%–30% more torque and speed. Because the same drive package can be used across three product lines, there is greater redundancy for customers using multiple technology platforms. Cutter design technology has also been improved to increase capacity and minimize particle size, thereby more directly addressing the unique requirements of the energy-from-waste sector.

With low-speed, high-torque technology, SSI shredders process a broad range of materials with low dust, low noise, and low operating costs. Ward lists types of materials handled, including some of the most difficult waste and material streams, such as mixed C&D, mattresses, carpets, railroad ties, stumps, furniture, and appliances. Once the bane of existence for shredders, metal is actually shredded, not merely sorted—thanks to shockload protection.

Industrial tub grinders, horizontal grinders, track grinders, shredders, and trommel screens are designed for applications as diverse as land clearing, high-volume composting, disaster cleanup and solid waste reduction. Ward says one of the most common uses in solid waste and recycling applications is volume reduction, which translates to reduced transportation and disposal costs as well as extended landfill life.

The processes involved include preshredding prior to sorting and separation to maximize overall capacity, optimize material flow, increase recovery rates and improve worker safety; primary shredding of bulky or contaminated materials before secondary processes to maximize system capacity and reliability; and fine shredding of residual materials, industrial byproducts, off-spec products, and confidential materials to meet specific size classification requirements.

Photo: Diamond Z The DHZ 7000 series grinder from Diamond Z is a high-capacity, low-maintenance model suitable for large-scale woodwaste and land-clearing operations.

While the processes are similar, each market has different processing and end-product requirements. The choice of equipment depends on the desired product specifications. According to Peterson, if C&D material is recycled in an enclosed environment, a slow-speed machine is generally chosen for the primary reduction because it helps separate the metal and other materials so they can be screened and sorted into useful products. The woodwaste stream is then further reduced with a high-speed grinder for boiler fuel, mulch, or compost. “If size reduction is the primary goal, high-speed grinders are the best choice for C&D applications such as shingle grinding or rail-tie grinding,” he explains.

High-speed grinders also work well in other C&D applications; however, they may need to be specially configured for varying feedstock. Shingle grinding requires special bits, hard liners, and unique grates. Extra water is needed for lubrication and cooling. More contaminated C&D or bulky MSW requires slower grinding speeds, a floating anvil, heavy-duty grates, a pinned rotor, and an impact-resistant conveyer conveyor belt.

Peterson’s largest grinder, the 950-horsepower–1,200-horsepower 67 series is suited to C&D applications because it can be configured for a slower rotor speed and it features a heavy-duty pinned rotor, impact-resistant conveyor belt, floating anvil, and heavy-duty C&D grates. Peterson mentions that it also excels in high-capacity mulch and composting operations.

Although most established customers have a pretty good idea of their needs, Donovan says it’s important to consider what is being processed, how much is being processed and what size end product is desired when selecting grinders and shredders. “We offer what they need, not just what we have.”

CBI’s flagship is the 8400, unchanged for 11 years. With two heads, it can convert from a chipper to a grinder with the change of rotors and screen system. The advantage over other microchippers, he explains, is that it can process different wastestreams with a change of attachments. Other benefits include a four-pocket chipper that consistently makes quarter-inch-to-three-eighths-inch-fiber-length chip and a solid steel rotor that can handle contamination, phone poles, and railroad ties. It’s available track-mounted, wheel-mounted, and stationary, in diesel or electric power. “You can adapt the machine to the need,” Peterson says. “Our models 6400 to 8400 are versatile.” He says that’s important these days, when customers are looking at different markets for additional work.

The Bottom Dollar
Production is to profits what cost is to expenses. Owning-and-operating costs must always be figured into the equipment equation. Such variables as fuel consumption, part-wear life and cost, maintenance costs, and machine availability are not always controllable but must be added into business calculations when bidding jobs. Some costs can be offset. For example, Peterson says fuel consumption per ton of output can be fine-tuned with different bits.

Product size is achieved by the feed and grinding system, grate openings, bit type, and rotor speed, explains Peterson. A machine that can adjust all these variables is capable of producing the biggest variety of valuable end products. “It’s important to be able to have multiple grates so the openings can be adjusted in each grate position to make the most consistent end product. The type of bits will affect the productivity in different materials and the operating cost.”

All Peterson grinders feature the company’s patented system with upturning rotor and adaptive control system. Peterson claims it will out-produce other high-speed grinders in most applications. “Production is much higher than [with] slow-speed machines in wood-based materials.”

The upturning rotors work well for land clearing, greenwaste and other applications with limited contamination, Donovan elaborates. The purpose-built rotors process material on the feed wheels before it gets to the release mechanism; faster rotors can maximize volume. There are, however, limitations. Downturn rotors are more forgiving of contamination. Unlike with the upturn, the hammers process against an anvil, which provides shear protection for the pin.

Saving money on equipment repairs is almost as good as making money. To protect machinery from contaminated feedstocks carrying uncrushable materials, Peterson grinders use a proprietary Impact Release System and Impact Cushion System.

In addition to saving the equipment, it’s important to save time. “One of the biggest factors is how much is the cost per ton to put material on the ground,” Donovan says. “You want more per hour for less per ton.” CBI’s design allows the hammer mills to work the material across the entire 60-inch infeed length, processing material more quickly. “Most patterns funnel the material toward the middle,” he details. “That creates more wear, so you have to change the tips more often.”

Tips last per the number of tons, not per hour, according to Crawford. Therefore, calculating costs per hour isn’t fair. Instead, costs are more accurately figured per finished ton or cubic yard. With two Caterpillar 320EL tracks and up to 1,000 horsepower, Diamond Z’s new 1460B tub grinder produces up to 95 tons per hour. Its 42-inch-wide Phase I and II conveyors stack material up to 15 feet high. Because it requires less material handling, it saves time and reduces operating costs. Similarly, with a quick 20-minute screen change and horsepower options up to 1050, the high-capacity DZH 5000 Series increases production by reducing downtime. Crawford considers the biggest machine to be the most efficient. Diamond Z grinders range from 24,000 pounds to 230,000 pounds. Each customer’s production requirements determine the needed size.

Mark Lyman, president of West Salem Machinery in Salem, OR, says his customers are usually already composting and know the size they need, so “they tell us what product they want. WSM builds 15 sizes of grinders—50 horsepower up to 1,500 horsepower—to fit a wide range of applications.”

Going Places
For those who need a little more direction, Donovan outlines different classifications for determining the appropriate machine. The most important consideration, he says, is the amount of contamination in the material.

As Crawford explains, there are modifications of basic grinders and shredders for different industries. “What you use for contaminated storm cleanup is different than what you use for wood and greenwaste.” Diamond Z offers tub and horizontal grinders from 300 horsepower to 2,400 horsepower, some of which are capable of handling scrap steel with 700-ton shear option car crushers.

Other factors include location. For sensitive environments, Diamond Z offers the only totally enclosed tub grinder. Capable of processing wood stumps, greenwaste, tires, and C&D waste, it’s a good option for highly populated locations because it maximizes safety.

For less populated but heavily contaminated areas, such as landfills and transfer stations, Crawford suggests a high-speed, mobile-mounted MSW grinder. The SWG 1600 is the first and only onsite mobile solid waste grinder targeted exclusively to process municipal solid waste and C&D disposal at production rates up to 300 tons per hour. Track-mounted and self-propelled, it can be driven on the working face of a landfill. Garbage is ground into a consistent product from fewer than 10 inches to fewer than 4 inches by 52 fixed hammers. The patent-pending screening-rod device controls the size of the end product and provides a quick cleanout system to remove contaminants from the mill area, making the grinder extremely tolerant to high levels of contamination from household waste.

The SWG 1600 features a diesel engine that produces 1,650 horsepower. Crawford indicates that diesel-powered grinders offer more mobility than electric-powered machines. Those, however, have an advantage when fuel prices are high and offer an attractive option for recycling yards and cogen facilities where mobility isn’t an issue. Ultimately, Crawford says, the electric power versus track-mounted diesel decision “depends on the raw product and the finished product.”

Stationary electrical recycling systems are on the rise, Donovan believes. To meet that demand and “become more of a one-stop shop [by] expanding opportunities for customers,” CBI offers the option of diesel or electric on all its portable machines. They even have a customer in Denmark who wants equipment to run on diesel five months and on electric power seven months. “We’re designing a machine with an interchangeable motor.” He says that’s indicative of their focus on attention to detail and a higher level of understanding. “Thinking outside the box creates opportunities.”

Similarly, most Peterson grinders are available in track-mounted and trailer-mounted versions, with diesel or electric motors. “The electric-drive machines can be equipped with variable-frequency drives to minimize peak current demand and provide variable grinding speeds,” he explains.

If You Can’t Stand the Heat…
The principle driver for high-speed grinders in the past was the desire to divert greenwaste from landfills. Peterson believes there’s still opportunity for growth in greenwaste diversion, but he views a new trend in North America: kitchen waste diversion. “A large portion of this kitchen waste will be composted aerobically. That will increase demand for high-speed grinders and screens. Bioreactor landfills and anaerobic digesters will also increase.”

With wet kitchen waste removed from the MSW stream, the remaining waste will have a higher energy value. In the future, Peterson thinks North America will follow the European model of generating more power from waste. “This trend will require high-capacity grinders and screens to reduce, sort, and classify the wastestream into a suitable fuel.”

Lyman agrees that the cleanup materials must be pulled out of the flow. “You need to fine-grind and screen to remove contaminants such as plastics, cardboard, and forks.” There are different approaches to a screening-and-grinding system for foodwaste, he contends. A simple one incorporates a primary grind, screening, and a finish grind. “You can go even simpler.”

If the customer’s compost facility is licensed for greenwaste and foodwaste, another option is to grind the material to a coarse product and mix in greenwaste. “Foodwaste can go with greenwaste in compost,” he notes. “Anaerobic digestion speeds composting.”

For combination foodwaste and greenwaste processing, Lyman recommends a primary grind with a 4-inch-minus horizontal feed grinder such as WSM’s 4064BM, a mid-size grinder with 500 horsepower.

Next, he suggests using a trommel screen to achieve a rough classification of 3 inches to 4 inches and smaller, followed by a regrinder to 2 inches or smaller, and then to compost. “Or you can skip the trommel screen and go to slow-speed shredder for a coarse grind, then to the regrinder.”

Kitchen waste reduction is a niche that Lyman envisions growing as we improve recycling rates and companies look for new areas. Because “methane gas is worse than carbon dioxide,” he believes future regulations curtailing greenhouse gas emissions may affect this industry. “As more thought is being put into it, we’re going to the next step. The driver is regulations that encourage recycling. Once it’s processed, it’s a good product.”