Metal Shredders and Milling

Post date: Jul 19, 2012 8:36:52 PM

According to a recent report by the Organization for Economic Cooperation and Development (OECD), there are approximately 300 shredders in America producing scrap metal. By contrast, China has only 30 shredders, according to the OECD report. Regardless of location, when those machines must be repaired or replaced, there are many vendors available to address that need.

The shredders made at Granutech-Saturn Systems “are suited for nonferrous or light ferrous metals. Our customers are looking for a lower processing volume than what is typically seen in the larger hammermill shredders. Typical volume through our equipment usually ranges in the 2 to 20 tons per hour range,” noted Greg Wright, director of sales.

The company offers the following products: The Roto-Grind – a single-rotor grinder used in nonferrous applications, typically aluminum. This is a ram-fed machine in which the ram feeds material to the rotor and uses a sizing screen to provide a consistently-sized product. The Roto-Grind rotor rpm is between 80 and 168, depending on the application.

The Saturn Shredder is a dual-shaft, slow speed, high-torque shredder. This shredder is used for nonferrous or light ferrous metals. It can handle tougher material than the Roto-Grind and unlike the Roto-Grind, it is capable of dealing with heavy ferrous contamination. Typical shaft speed is between 11 to 30 rpm.

Granutech’s Grizzly product is used as a secondary shredder to achieve maximum size reduction. It utilizes a 19,000 lb. rotor spinning at 321 rpm with rotary knives, which cut against stationary bed knives. A screen is also used to achieve product sizing. Applications include aluminum, e-scrap and tires.

“For over 40 years, we’ve offered size reduction equipment to the recycling industries. Our products include the MAC line of car crushers, Saturn Shredders and Granutech tire processing equipment. When purchasing some of this equipment, buyers must become acquainted with EPA, state, and local regulations concerning restrictions for air quality or other factors. Customers in this market may also sometimes face hurdles in obtaining the appropriate permits to operate,” Wright said.

SSI Shredding Systems has provided metal shredders worldwide for over 30 years. The SSI shredder line starts at 200 h.p. and ranges up to 800 h.p. Shredders in the 400 h.p. range are not uncommon for high volume applications.

Dave Wilson, technical sales, described the machines available from SSI: “We manufacture four types of shredders, all relatively slow speed/high torque, compared to high-speed hammer mills or auto-shredders. SSI shredders are used for processing metal, both ferrous and nonferrous. The most popular products are larger shredders for the most demanding applications at the highest volumes.

“Our Pri-Max and Dual Shear models are versatile and utilized at the front end of metal recycling operations. For ferrous materials like appliances, the Pri-Max PR4400 and PR6600 are capable of high-volume processing. They are not car shredders and are not recommended for processing heavy ferrous. The slow speed shredder is the ideal first step in a reclamation line because the system can be batch fed, handles a wide range of scrap, and reduces the material down to a small size. In some cases primary shredding is the only size reduction required but it can also be an ideal first step in preparing the material for further processing, via secondary shredding equipment.

“Reliability is the leading advantage of a slow speed. Minimal noise, dust, vibration, foundation, maintenance, downtime and relatively low operating cost are other advantages of slow speed, high-torque technology. Industry regulations continue to evolve, regarding dust control because the issue has become more of an issue in recent years.”

Wilson stated that nonferrous applications are also popular uses for the SSI slow-speed, high-torque shredder machines. Baled or loose scrap aluminum, copper, radiators, wheels, wire and extrusion are some nonferrous applications well-suited to SSI products.

Special shredding technology is required to handle the scrap that contains ferrous and contaminants. These applications require systems that are designed with shock protection features such as automatic reversing, which protects the shredder from damage when processing foreign materials. “Thanks to low rpm cutting and shock protection, the chance of damage to the equipment is minimal when processing scrap. The cutter should also be designed to be abrasive-resistant, as lower grade scrap often has sand, glass, dirt and other unfavorable contaminates that accelerate cutter wear.

“If smaller particle size is required, it is common to use two shredders to process the materials. A pre-shredder like our Pri-Max breaks open the bales and a second shredder processes the shredded scrap further. It is possible to achieve high rates and a small particle size with two, slow-speed shredders and no sizing grate or recirculation. Often the second shredder can be a dual shear with a narrow cutter, which is 2 inches wide and produces a smaller, more consistent particle size. This double-stage concept with ferrous removal is a good option for achieving the cleanest nonferrous scrap,” Wilson said.

When a screen is eliminated from a system, Wilson explained that “the capacity increases and maintenance often decreases. However, some applications such as auto shredder residue require a particle size smaller than a single or two stage shredder can provide. Screen-based shredders such as the SSI Quad are ideal for reducing material to a very small, consistent size, such as 1.5 inch minus. The Quad is a heavy-duty, slow-speed shredder but it also incorporates the integrated screen feature. It is a compact system that produces a small particle size in a one-step operation.”

Bernhard Mueggler, president and CEO of UNTHA America, described the shredder market as “mostly determined by commodity pricing – while legislation continues to push for additional recycling levels. The industry will likely consolidate over the next few years as smaller operations are acquired by regional and/or national companies.”

UNTHA manufactures over 400 shredders per year, for various applications. “We have developed and produced innovative shredding solutions for individual tasks for over 30 years. In doing so, our customers and markets determine the direction of UNTHA,” Mueggler said. He then highlighted the features of two of their products and both are used if high plant availability, low maintenance cost and small footprint is required.

UNTHA’s S-120 heavy duty two-shaft shredder offers size reduction without a defined particle size. It is a high-torque, low RPM machine with low emissions and vibration. The intelligent cutting system and drive allows the cutting power to be increased by 70 percent for a short period of time. The S-120 offers a cutting system protection, shaft ventilation, wear protection, electronic overload protection, wear plates and is available with electro-mechanical or an electro-hydraulic drive. An optional variable frequency drive (VFD) offers increased throughput control, to reduce start-up peaks. Throughput can handle up to five tons per hour. The machine is used for nonferrous and ferrous shredding and electronic scrap and has a low, overall cost.

The UNTHA heavy duty 4-shaft shredder series (RS50 / RS60 / RS100 / RS150) offers size reduction with specific particle size requirements. Features include a very large screen area, pre-shredding and secondary shredding in one step, and modular systems to accommodate individual customer requirements. It is a high-torque/low-RPM machine with integrated electronic shut-down to protect the cutting system, multiple shaft bearings and a multi-stage sealing system.

The reinforced steel frame is rugged and has a cutting tool (with highly flexible cutting system configurations) with an integrated flange that eliminates spacers. The machine generates consistent particle size for effective downstream processing and the gravity feed eliminates ram for most materials. Throughput can handle up to 10 tons per hour and like the S-120, the machine has an optional VFD, shreds electronic, nonferrous and ferrous material and has a low overall cost.

Read more