Mechanical Material Management

When planning for a construction and demolition project, a contractor includes his labor force, hand and power tools, heavy equipment, fuel, office trailers, utility hookups, building materials, and dozens of other necessary items. What is often forgotten is equipment for processing and reusing the materials generated by demolition, renovation, and construction. This debris is not mere waste and can provide valuable building materials from aggregate made from crushed concrete to decorative mulch made from chipped wood, provided that the contractor has the foresight to use them. 

Types of Grinders 

According to Ted Dirkx, sales manager for Vermeer Recycling and Forestry equipment, "High-speed horizontal grinders and tub grinders, as well as for slow-speed shredders, are the most common types of wood process equipment. High-speed grinders are productive for grinding organic wood waste and efficient for producing a consistent material size. Low-speed shredders can also process organic material, but they are not as productive and do not produce as nice of an end product. However, low-speed shredders are more tolerant when processing wood material that contains contaminates. The ability to process organic and processed wood material make them more versatile than high-speed grinders. However, depending on what the processed material will be used for, facilities may still need to regrind materials processed by shredders to achieve the desired final sizing." 

"The three most widely used machines for processing wood waste material are high-speed horizontal grinders, high-speed tub grinders, and slow-speed shredders. Determining which machine type to use depends on the incoming material type, size and shape; facility location; and the kind of end product produced. For example, tub and horizontal grinders are most often used for processing organic wood waste because they can reduce material to smaller sizes faster and more efficiently than most shredders. However, shredders are a viable option for smaller recycling operations and handling processed wood material, as well as other building materials and debris. Horizontal grinders are efficient at handling longer material. So, if a facility receives a lot of long-cut tree branches and limbs, using a horizontal grinder can help reduce the cutting time before processing material through grinders. Horizontal grinders are also good at handling loose green waste." 

"Tub grinders can handle bulkier materials like tree stumps, as well as processed wood material like pallets. Tub grinders use gravity instead of conveyor belts to feed the hammer mill, so there are fewer moving components on a tub grinder than a horizontal grinder. Tub grinders are efficient at processing loose green mate-rials. Slow-speed shredders neither have the same production levels as grinders nor are they as effective at sizing materials. But they are typically more tolerant when processing material with many contaminates. To achieve the appropriate end product size, many facilities use shredders to pre-size material containing contaminates, like building materials, and then a grinder to achieve the desired final sizing. 

"There are several factors to consider when determining what machine or machines will deliver optimal efficiency and production rates, including species of trees most common in the area, the volume of material being processed, and worker availability. The hardness of the wood being processed can impact production rates, as well as the sizes of the material being fed through the grinder or shredder. At facilities that are receiving large volumes of organic wood waste material, a high-speed tub grinder or horizontal grinder delivers high production rates and produces consistent material sizes that can be resold at mulch, biofuel, or turned to compost. However, a slow-speed shredder may be a better investment if a facility isn't handling much organic material and just looking to reduce material mass. It won't deliver the same production rates as high-speed options, but shredders will allow them to handle a broader range of material types. The other factor waste managers need to consider is the size of their team. If there are labor constraints, investing in a high-speed grinder may allow them to process a lot of material in less time than it would take with a shredder, which can free up their employees to handle other jobs that need to be done."

What are the important operating characteristics of grinders and shredders? How does an operator evaluate his choices between different makes and models? How does the operator match his production needs to the right machine? Nine characteristics define the capabilities of grinders, shredders, and chippers. First are the four physical characteristics:  

• Weight (measured in tons) is the overall classification for grinders (small units weighing up to 20 tons and larger units weighing as much as 60 tons) since it is directly related to both power and other aspects of production. Bigger is often better with larger units able to handle a wide variety of materials, and smaller units being more specialized. 
• Feed opening (measured in square feet) determines how large an object be for processing or if the object has to be broken into small pieces beforehand. Large openings opening have diameters up to 5 feet with smaller units being only 2 feet. 
• Transport mode (measured in time to relocate) with smaller grinders being more mobile than larger models. Mobility can be restricted by rough terrain, steep grades, or limited access. If the productivity of the unit justifies the additional hauling expense, it sometimes makes economic sense to site a larger grinder near the site and haul the material out to it for processing. 
• Tub diameter (measured in inches) like the feed opening, determines how much and what size of material can be processed. But in addition, it determines the number of hammers and blades that the grinder can utilize 

Then there are four operating characteristics: 

• Power (measured in horsepower) determines how much material can be processed per unit of time and the relative sizes of the material objects are processed. The most important power aspect is not the overall power, but the amount of power delivered to the business ends of the grinders knife blades and hammerhead. 
• Production rate (measured in cubic yards per hour) represents the maximum rates at which material can be fed into the grinder. This will vary with types of materials and even with different applications of the same materials (a wooden stud will take longer to chop up than a wooden brush cleared from the job site). 
• The discharge rate (measured in cubic yards per hour) should at least equal the feed rate, typically managed by dual auger feeds or conveyor belts varying in width from 2 feet to 5 feet. 
• The drive train (measured in horsepower/torque) is the application of the unit's power rating and operates the hammer, blades, and conveyor belt. 

Lastly, there is the catch-all characteristic associated with available options:  

• Extras (measured in money) include a multitude of options (lock packages, toolboxes, specialized paint coatings, fuel pumps, and backup power units. 

Major Suppliers and Manufacturers  

Eggersman is a German firm that specializes in bulk and pre-shredders. Their slow-running TEUTON shredders from Eggersmann provide an almost inexhaustible variety of applications. If necessary, a defined end product can be achieved in just one work step. The machines of the TEUTON series are used for shredding waste, biomass / organic material, tires, plastics, and much more. Depending on the area of application, the shredding tools can be exchanged within a very short time to ensure optimal adaptation to the material. The optional sieve basket system also enables shredding to a marketable grain size in just one operation. The TEUTON shredders meet the expectations of plant managers and users in regards to full power, defined grain size in the discharge, availability of the machine, operational safety, and low operating cost. The shredders of the TEUTON series not only work at high power levels but also achieve optimal results thanks to the special technology of the shredding tools. The tools can be changed quickly and easily and ensure that the machine can be optimally adapted to any material. In addition, application-specific programs can be selected very easily via the touch panel. 

In addition to the TEUTON power shredder, Eggersman provides a line of pre-shredders, the FORUS SE 25 and SES 25. These pre-shredders are slow-running shredders equipped with two shafts for shredding refuse, waste, and wood. These systems are applicable for the shredding and blending of commercial or electronic waste, plastic sheets, and paper. They are equally useful for an agricultural contracting business for the treatment of wood and biomass that needs a suitable pre-shredder for material pre-treatment. It can also be used for specialized applications such as the shredding and composting of grass and tree cuttings. The FORUS SE 25 slow-running pre-shredder is an appropriate choice for the efficient shredding of a wide variety of materials, including all types of refuse and wood, household, bulk, or commercial waste, plastic sheets, paper, and electronic waste, reclaimed and demolition timber, green waste, and rootstocks. Depending on the input material, throughput is between 10 to a maximum of 40 tonnes per hour (household waste: 40 t/h, wood 15-20 t/h, commercial waste 10-15 t/h). The final particle size varies from 0 to 350 mm and is dependent on the input material and the crushing beam selected. This can be raised and lowered hydraulically and is available from type A1 to A5, depending on requirements. The shredding unit of the mobile shredder can be easily adapted to the material and the required final particle size. Both rotors are independent of each other in their rotating direction and rotational speed. 

Their stationary Pre-Shredder FORUS SES 25 is equipped with two shafts for stationary shredding. It is a reliable high-performance machine for pre-shredding and evening-out waste inputs. It can process electronic scrap, foil, paper. A biological waste treatment plant can use the SES 25 for shredding scrap wood, shrub and hedge cuttings, or other structural material. It is a universal shredder that adapts multiple requirements. The stationary primary crusher FORUS SES 25 is equipped with an electrical drive. The drive, as well as the electric control system, are both incorporated into the machine frame which allows for a very compact and space-saving machine design. The stationary pre-shredder is equipped with a hydraulically tiltable chute with a 4 m³ filling capacity for easy infeed by wheel loader. The filling volume can be increased considerably with an additional extension. 

The FORUS two-shaft shredders from Eggersmann offer a high level of operational reliability thanks to their hydraulic drive. The shafts can be controlled asynchronously either individually or by configured programs. This optimizes the results for most crushable materials and at the same time enables self-cleaning for coiled materials. The various secondary crushing beams allow the final grain to be defined up to a marketable end product. The feed hopper with a capacity of 4 m³ can be hydraulically operated at the push of a button, ideal for wheel loaders or excavator feeding. The hydraulically adjustable over band magnet can be adjusted in height via remote control and optimally adapted to the material/substance flow. The user-friendly and intelligent control design ensures maximum machine availability with optimum utilization. The performance and level parameters as well as error messages and maintenance intervals are displayed digitally and ensure a trouble-free and reliable shredding process. Like the TEUTON shredders the FORUS shredders can also be used for shredding bulky household waste, commercial waste, foils, paper, glass, asphalt, pressed bales, and electronic scrap just as for old and demolished wood, green cuttings, biomass, or rootstocks. 

EDGE Innovate Ltd provides a range of slow-speed, high torque waste shredders that are probably the most flexible and functional slow speed shredder on the market today. Designed with strength, durability, and serviceability in mind, their shredders can handle a multitude of materials in a variety of applications. With an extensive range of both rapid volume reduction and intricate piece sizing solutions available, their shredders can be employed as either a primary or secondary shredder and can be used in work environments as diverse as waste management companies to biofuel producers. As the recycling industry changes with the adoption of new regulations and stringent requirements placed on MRFs, EDGE provides much-needed adaptability. Whether it is processing C&D waste, utility poles, or domestic household waste, the range of shredders from EDGE can be customized to provide the right tonnage at the desired piece size. 

They have a wide range of shredders in their product line. Their twin shaft waste shredder is powered by a Caterpillar C9.3B Tier 4 Final / STAGE V 310Kw (420 hp) engine. Its twin Shaft design provides exceptional intake capability, results in less wear and tear, is self-cleaning, and prevents material wrapping. Its intelligent self-protecting control system is the latest version of the EDGE Operating System (EOS) with onboard load sensing diagnostics. Their slow-speed horizontal shredder utilizes a horizontal feed delivery system with a 42-inch diameter top feed roll ensures high production capacity. Its unique material management system relies on an intelligent self-protecting control system. Its extra-large (XL) slow-speed waste shredder has a shredding area measuring 6’5” x 6’6” and a hopper capacity of 4.6 cubic yards. It is the lowest maintenance cost waste shredder on the market. EDGE’s mobile waste shredder is a portable unit that can be set up where needed at the job site. 

eFACTOR3, LLC offers a large variety of pre-shredding, screening, sifting, shredding, cleaning, granulating, and extrusion equipment along with conveying and separation equipment, systems integration, and installation. The designs of their systems are based on a keen understanding of environmental, engineering, and equipment issues for a wide variety of applications from shredding to separation to screening. Their systems are used by an extensive list of material management industries: landfills, transfer stations, municipal solid waste, bulky waste, post-industrial waste, construction and demolition debris refuse-derived fuel (RDF), paper and cardboard recycling, and materials recovery facilities.  

Their line of METSO shredding equipment helps to extend the life of a landfill through improved compaction rates, improved material decomposition, and increased bulk density—making landfill operations more economical purposes. Higher volumes of material can be generated by pre-shredding the waste in a transfer station or MRF. This ensures that even the bulkiest of items get broken down and allows for greater tonnage per trailer load. Their shredding solutions also help to improve the separation of materials using pre-shredding and wind sifting to separate waste into heavy, medium, or light fractions. And by shredding the waste before it is baled, bale weight can be increased. The METSO line of shredding equipment is also very effective in reducing the number of fines in the final shredded product, this is true for both bulk production rates and small volume applications where they offer a single shaft shredder. In addition to shredding systems, eFACTOR3 offers separation technologies capable of removing contaminants from the paper stream. 

METSO pre-shredders come in four different sizes powered by an electrically-driven power pack with selected quality hydraulic components. All four series are based on patented technology and use hydraulic operation, open cutting tables, and large knives made for heavy-duty use. The METSO M&J K-Series includes two models, the M&J K160 and M&J K210. They provide operational flexibility for sites with a 5–45 tons per hour production requirement. They have a unique bi-directional shredding system (both synchronous and asynchronous) with two shafts that provide superior performance with all waste, resulting in unbeatable uptime. Their proven knives geometry reduces the risk of wrapping on the shafts, resulting in less bridging and fewer cleaning stops to improve capacity Modular design ensures that only relevant components need to be maintained, ensuring a longer life with lower operating costs. 

The Metso M&J 2000S is a single-shaft stationary shredder that features PLC-controlled automatic reversal and shredding in both directions. This innovative feature prevents material from wrapping around the shaft, helping eliminate bridging issues and preventing breakdowns. This machine uses the same main components and shredding power as its big brother the 4000-S. Its open cutting table and a shredding zone that is both long and wide make this mid-size model appropriate for processing inputs such as MSW, bulky waste, industrial waste, C&D waste, etc. Depending on the type of waste the cutting table specified and the feed set-up, throughputs of 5–70 tons/hour are within easy reach. Their Metso M&J 4000S stationary shredder is designed to meet the special needs of plants in which the incoming material is extremely varied in both size and composition, and may also contain unpredictable components. The combination of a large cutting table and a twin-shaft shedding system makes it possible to shred almost any kind of material and that there are no problems with bridging. Depending on the machine configuration capacities of 10-100 Tons/hours are achievable. The Metso M&J 6000S is one of the largest stationary shredders currently available in the world. This giant shredder is equipped with two 13-feet-long shafts and an exceptionally large shredding zone that is approximately 9 cubic yards in size. Together, these features make this top-size unit ideal for shredding unusually bulky or very heavy inputs in large volumes, up to 20–200 tons per hour. 

Vermeer Corporation, a supplier of grinder tips, screens, or drums, ensures that their equipment works at optimal production with their Vermeer Damage Defense system technology. This system is designed for any tub or horizontal operation that may encounter metal contaminates mixed in with incoming material. If the grinder’s mill comes in contact with metal while grinding, the Damage Defense system will alert the grinder control and automatically initiate the shutdown process. This system reduces the likelihood of metal being pulled into the mill by reversing the feed system to help prevent significant damage to the grinder. The Vermeer product line includes the Series III hard-faced patented duplex drum with reversible hammers and cutter tips for ease of maintenance and extending the life of these wear parts. This is a newly patented design and is built off the proven cutting performance of previous Vermeer duplex drum designs and makes maintenance more convenient. Vermeer possesses an exclusive in-house grinder screen manufacturing process to help maximize the performance of their horizontal and tub grinders. Screen styles are available in a variety of sizes making it convenient to find the right fit for optimum productivity and product consistency. 

A key component of their product line is their wide variety of specialized grinder tips. Increased carbide coverage makes Vermeer grinder tips make them durable. They come in seven different styles. The premium grinder tips have the highest carbide content and feature increased welds on the ends and a single weld on the sides, delivering the longest life of Vermeer carbide grit tips. The Pro grinder tips have both ends and sides welded to provide an intermediate life span. The standard grinder tips are designed to be an economical choice without side welds and offer a moderate life span. Wide block tips are the most common in the industry and can be used in a variety of applications such as land clearing, regrind, pallets, compost, and green waste. Abrasion-resistant (A/R) tips are used when highly abrasive material is being processed, with their flat face design, infused with tungsten carbide crystals in the casting block, they are best suited for applications that contain sand, dirt, and other highly abrasive materials. Wingtips have a unique design with an overlay of carbide that provides an effective solution for processing large-diameter woody materials. Impact-resistant (I/R) tips offer an alternative to wingtips and are used to process large-diameter material. Narrow block tips only in the standard configuration are available for tub grinders and select horizontal grinders and have an overlay of carbide along the sides of the block, making them an effective solution for processing large-diameter woody material. Sharp tips are precisely designed for cutting and are most commonly used on large diameter wood for max production and the least amount of fines 

The Benefits of Shredding and Grinding 

The recycling of C&D debris provides multiple economic gains and direct environmental and social improvements as well. These include job creation, increased economic activity, and improved operational efficiencies regarding material utilization. Environmentally, shredding and grinding allow for resource conservation and minimize the use of landfills. This is accomplished by extending the operational lives of existing landfills by avoiding airspace utilization normally required by the disposal of the debris. This in turn reduces the need to construct new landfills or expand existing landfills. Air pollution is reduced by minimizing truck emissions (especially nitrogen oxide) by avoiding the hauling of debris to a landfill. Fewer aggregates would be needed from a quarry by using crushed concrete, a material with engineering characteristics that are comparable to natural quarry stone. Savings also occur when recycling and reusing metals, wood, and plastics. Recycling C&D is not the whole story. Recycling paper products, for example, minimizes deforestation as well as the other resources needed to manufacture new paper (water, electricity, etc.). Creating new products from recycled materials results in a smaller carbon footprint.