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Avoiding garbage in: the path to a smooth metals shredding operation starts with the incoming inspection.

Metals shredder operators in 2005 benefit from more powerful shredders and more effective downstream sorting systems than have ever been available.

But even with the improved systems available to recyclers, the human factor can still be critical in preventing downgraded material and costly equipment damage.

In a presentation to the 2005 ISRI (Institute of Scrap Recycling Industries Inc.) Operations Forum earlier this year, consultant William Baumgarmer noted, "Unless you are a scrap dealer who wants to buy dirt instead of automobiles," then a source control and incoming inspection program is critical.

DAMAGE CONTROL, Shredding and post-shredder sorting equipment is increasingly designed to be more automated and require the use of fewer human hands and labor hours.

Human eyeballs, however, still play an important part in determining how well a metals shredding plant functions, affecting everything from product quality, profitability, machinery damage control and avoiding the introduction of hazardous materials.

Much of this human touch must come up front at the scale house and inspection area, while the operator in the shredder tower also can play an important role in boosting product quality and avoiding equipment downtime.

In terms of profitability, initial inspectors and scale house personnel are critical to ensure that the shredder feedstock being purchased by weight consists of a higher percentage of ferrous and nonferrous metals and a lower percentage of contaminants such as dirt, tree limbs, concrete and asphalt. As Baumgartner observed dryly at his Operations Forum presentation, such materials do not represent "a high-profit part of your business."

Another critical part of the pre-inspection involves finding materials that can damage the shredder or otherwise cause operational downtime.

Even though reject doors are designed into shredding plants, large, heavy unshreddable objects, such as hunks of hardened steel are still better off never reaching the hammers and walls of a shredding chamber. Operational efficiency takes a hit whether downtime ensues or whether some wear parts are damaged before they reach their maximum lifespans.

Sealed containers (such as propane tanks) are another item to look for in the inspection process. While many shredder operators report that the sound of a propane tank blowing up inside the shredder chamber is a case of a bark that is worse than the bite, there are still many good reasons to monitor incoming scrap for tanks and other sealed units.

Shredding plants that become blase about propane tanks may be prone to eventually letting a more harmful--perhaps hazardous or more powerfully explosive--pressurized container into their shredder. The consequences can be damaging financially, environmentally and possibly to the safety of employees.

Less dramatic but still important is to be on the lookout for wiry and stringy materials that can wrap themselves around the rotor of a shredder. While such materials may not cause catastrophic damage, they can reduce the performance of a shredder and lead to intermittent periods of downtime when the mill is stopped so the unwanted material can be extricated from the chamber.

Perhaps the most difficult part of putting in place a thorough inspection process, however, is designing it so that it can still be done quickly, before a dozen or more trucks are backed up and waiting to get to the scale.

CHECKING IT TWICE. When it comes to profitability, a shredding plant's best friends can be experienced, sharp-eyed personnel at the scale house and in the shredder control room.

But whether breaking in new employees at these important positions or simply refreshing the memories of experienced personnel, Baumgartner recommends that employers maintain a checklist of materials that should be pulled out of the shredder feedstock stream.

A checklist can be designed so that certain hazards are aligned with the type of purchased scrap in which they are most likely to be found:

* Auto hulks should be monitored for a weight reading that may be above an established "per body" weight; at least one vehicle per truckload should be checked for gas tank and battery removal and for hidden objects (anything from propane tanks to cinder blocks).

* Appliances can offer a range of contaminants to be aware of (refrigerant fluid being the most notable), and Baumgartner says the EPA even has oiltesting requirements for the motors on some appliances.

* Demolition scrap can contain a variety of unwelcome materials, ranging from asbestos and lead paint to mercury-vapor fluorescent lights and normally occurring radioactive materials (NORM) that can be contained in soils attached to building materials.

* Galvanized scrap, while certainly containing zinc that can be unwelcome at some consuming destinations, may also contain trace amounts of lead and cadmium that will be unwelcome everywhere, according to Baumgartner.

Establishing an inspection program is not a static process, however. The nature of materials coming into a shredding plant can change, as the last several years have demonstrated.

Shredding logs and loose bales are becoming more common as feedstock, as they offer a way to bring material in from a wider perimeter, and shredding such dense material can improve the plant's productivity.

An unintended downside, however, is that such forms of scrap can bring with them unpleasant surprises. Whether from suppliers purposely trying to conceal a heavy unshreddable inside a bale or because of an honest mistake, problem materials can elude visual inspectors when soft shredder logs and bales are used as infeed material.

Scrap in these forms should not be avoided, but purchasing logs and bales leads to another important point from Baumgartner: The real pre-inspection process starts with the scrap buyer. While the pressure of being on the front line applies to those at the scale house and in the shredder control room, Baumgartner notes that the process of acquiring high-quality, safe feedstock starts with scrap buyers.

"Buyers need to truly know who they are buying from," Baumgartner told Operations Forum attendees. "And they need to know to avoid types of materials that can cause problems at the yard."

Through all steps, Baumgartner urged shredding plant operators to maintain rigid attention to documentation, again, starting with the buying process but also including the removal and disposal of contaminants. "If it's not in writing, it didn't happen," remarked Baumgartner concerning the position government regulators are likely to take should there be an inspection or incident follow-up procedure.

For scrap companies, the good news is that equipment manufacturers have made strides to increase shredding plant automation. However, such automation has not reduced the need for sharp eyes and minds to keep close track of operations from scrap buying through incoming inspection to the disposal of unwanted materials.

The author is editor of Recycling Today and can be contacted at


The Operations Forum hosted by the Institute of Scrap Recycling Industries Inc. (ISRI) has become a gathering place for metals shredder operators and their suppliers.

More than 340 attendees gathered in San Antonio in late January for the 2005 Operations Forum held by ISRI, marking record attendance that was up by more than 120 over the 2004 event, according to the event's organizers.

While attendees could choose sessions from a number of topics, including metals identification, yard management and operating safety and environmental considerations, the most heavily attended sessions focused on running metals shredding plants.

Shredding-related topics covered included rotors and wear parts, inspection and infeed methods, and downstream sorting and separating.

A session on castings yielded a comment from Randy Brace of Riverside Engineering Inc., San Antonio, that "casting consumption is significantly lower" on larger shredding plants, which he contended is one of several reasons why larger plants offer increased efficiency.

The 2006 ISRI Operations Forum has been scheduled for Jan. 9-11 in Atlanta. More information can be obtained from ISRI at its Web site,, or by calling (202) 737-1770.
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Comment:Avoiding garbage in: the path to a smooth metals shredding operation starts with the incoming inspection.(SHREDDING EQUIPMENT FOCUS)
Author:Taylor, Brian
Publication:Recycling Today
Geographic Code:1USA
Date:Aug 1, 2005
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