November/December 2010
Magnetism and its effect on ferrous materials create some unique—and perhaps unexpected—hazards for those working with and around magnetic scrapyard equipment.
By Tim Shuttleworth
Industrial-strength magnetic scrapyard equipment such as lifting magnets, scrap drums, and eddy-current separators can increase a recycler’s productivity and profitability. Magnetic separators remove unwanted ferrous metals from bulk loads to improve product purity, protect sensitive processing equipment, and help prevent fires or explosions by keeping hot metal out of shredder fluff, while lifting magnets are an efficient way to move ferrous scrap. Either as individual units or as parts of a larger system, this equipment efficiently and economically processes commingled recyclables, shredded automobiles and white goods, electronic scrap, glass cullet, PET, and many other scrap materials.
The same properties that separate and move scrap materials so effectively can create hazards in a scrapyard, however. Many of the hazards, such as the risk of electrical shock or of getting clothing or extremities caught in a rotating shaft, are similar to those you’ll find in other scrapyard equipment. But magnetic equipment also comes with unique risks that can cause injuries that range from pinched fingers to crushed hands to the loss of extremities, even death. When operating a permanent magnet or electromagnet—or when working near a magnet that’s in use—workers must follow safety precautions. Even a minor lapse in operating procedures can cause serious injury.
Today’s magnets are much stronger than those in use just 10 to 15 years ago. Magnets made from alloys of rare earth elements can produce a magnetic force that’s more than 10 times that of ceramic magnetic circuits and up to 25 times that of conventional permanent magnets of the same size. Operators must understand the composition of the magnet they’re working with and its degrees of attraction to other objects and equipment to ensure they keep hand tools and other items a safe distance away from it. Some workers are not aware of the risks associated with the magnets they work with, however, nor do they understand the magnitude of the magnet’s strength. This can lead to accidents.
Magnet accidents are avoidable, as Eriez’s experience can attest. Eriez employs 300 workers at its headquarters and magnet manufacturing facility in Erie, Pa., and had gone more than 650 days without a lost-time accident as of mid-October—an achievement credited to increased employee safety awareness. Safety starts with common sense and, of course, following safety guidelines. To avoid magnet injuries, yards must make sure their employees know the risks involved with each piece of magnetic equipment and have a basic understanding of how magnets work. Further, they should post warnings where magnets are present and enforce proper procedures for working around them.
Overall Magnet Safety
Awareness is the first step in any safety training program. Scrapyards must alert workers to potential hazards in their work environment, such as by placing “strong magnet” warning labels on or next to the area where the magnet is installed. The magnets should already have warning labels affixed to them when they arrive from the manufacturer, and manufacturers should send additional warning labels upon request.
Magnets will violently attract carbon-steel chutes, carts, tables, pipes, I-beams, or other magnets in a split second. If a worker’s hands or fingers get caught between the magnet and carbon steel, they can get pinched, trapped, or even crushed. Even if a magnet is installed properly, nearby carbon steel could make the magnet less effective. The use of 300 series stainless steel or other nonferrous materials, such as wood or plastic, in areas near the magnet will lessen this effect.
Most magnet accidents occur when workers transport the magnet or clean the magnet, the term for removing metal from its surface. Sometimes they must pull the magnet from its housing and take it to another area. Because the magnetic field is invisible, workers sometimes forget the magnet’s attractive properties while they’re handling it. If a worker must transport a magnet to another area, that magnet should never come close to carbon steel. Before moving the magnet, workers should inspect the path for potential hazards and create a barrier using a container made of wood, plastic, or other nonferrous materials. The magnetic field will still pass through the barrier, but it will lessen the magnet’s holding force.
Common Magnet Hazards
In addition to the risk of injury from unseen magnetic forces, workers must be aware of other possible hazards when working with magnets:
Electric shock. Many yards operate electromagnetic scrap drums, which remove ferrous material from shredded automobiles, chips, turnings, and stampings. Typically, an electromagnet uses direct-current electricity rather than alternating current. A bridge rectifier inside the magnet’s panel box converts AC power into DC power. Workers should use extreme care when opening the control-panel box or touching any electrical apparatus inside. If they don’t handle the electrical components correctly, they can receive an electric shock from the DC current. A qualified electrician should perform any required maintenance or repair work to the electromagnet’s control unit. Considering electromagnetic scrap drums’ shock hazards, permanent magnets are a safer alternative. Permanent magnets don’t require electricity, which eliminates the risk of electric shock.
Falling material. Workers should never stand directly beneath a suspended overhead magnet in case it drops its load due to a power loss or unstable magnetic force. Dropped loads can occur even without a total power loss: A split-second power spike is enough to disable the magnet and cause the load to come crashing down, which could cause serious injury. An oily or slick magnet surface also can cause a dropped load by interfering with the magnet’s pulling force. Further, as a magnet lifts scrap off the ground or conveyor belt, it might not fully engage all of the pieces. Because this is difficult to detect, it’s best to keep a safe distance. Finally, all electromagnets gradually lose strength as they heat up during use, which can lead to the items last picked up being dropped as a load is moved.
Flying debris. Scrap drum magnets, eddy-current separators, and suspended magnets all create a risk of flying debris. Metal fragments can dislodge from the magnet and get kicked from a rotating shaft or peel off an overhead magnet. Not only can the size and speed of the projectile cause injury, the metal debris also can become red hot as it makes contact with the rapidly spinning rotor from a scrap drum or eddy-current separator. Operators should maintain a safe distance, wear protective equipment, and never become distracted while the equipment is repelling metal. Also recognize the product stream and understand the angle of trajectory. For example, a nonmetallic fragment comes off a head pulley differently than a piece of ferrous metal.
Stuck ferrous metal. Occasionally, carbon steel attaches to the eddy-current separator rotor. Ferrous metal that clings to the rotor heats up quickly and can start to burn through the shell, damaging the equipment. If this occurs, stop the equipment and let it cool. Never pull hot metal off the rotor.
Rotating shafts. Most rotating shafts in magnetic separators come with guards or hoods to prevent injury. Even with the guards in place, however, a piece of clothing could get caught in a moving chain or sprocket if a worker comes too close to the equipment. Most recycling facilities set up walkways next to the magnetic separation equipment to prevent workers from catching their clothes in the machine. There also is a chance that a worker could get a hand or finger pinched between the chain and sprocket during routine maintenance. Allow extra time to properly clean the equipment, and make sure to completely shut down and lock-out/tag-out the machine before you start.
Medical device interruption. Strong magnetic fields have the potential to adversely affect medical devices such as pacemakers and surgically implanted intracranial aneurysm clips. Workers who have these medical devices should consult their physician and the medical device manufacturer to determine whether they should keep a safe distance from any industrial magnet.
Data loss. Though it’s not a physical safety hazard, placing an electronic device too close to a magnet can cause data loss or erasure. In general, magnets are most harmful to magnetic data storage devices such as hard disks, floppy disks, and flash memory. They also can erase a credit card’s magnetic strip. Keep anything with magnetic storage—including a cell phone—as far away as possible from a magnet to avoid critical data loss. Further, if you have a cathode-ray tube monitor, placing the monitor near an industrial-strength magnet could cause image loss, especially after repeated exposures.
Industrial-strength magnets play an important role in recycling facilities around the world. Today’s facility managers and maintenance supervisors recognize the need for these powerful magnets in their recycling operations and are emphasizing the importance of magnet safety training to keep their workers safe. Each type of device—whether it’s a scrap drum, lifting magnet, eddy-current separator, head pulley, or suspended permanent magnet or electromagnet—has its own set of safety concerns. If handled properly, however, they are a safe, efficient way of removing unwanted ferrous elements and moving ferrous scrap.
Tim Shuttleworth is president and CEO of Eriez, an industrial magnet manufacturer in Erie, Pa. For a face-to-face consultation on safety and industrial magnets, contact eriez@eriez.com.
Basic Magnet Safety Guidelines
--Maintain a safe distance from any magnet when holding ferrous material, especially handheld tools.
--Post warning signs.
--Avoid placing a magnet on a metallic surface.
--Lock-out/tag-out when working on an electrical control panel.
--Don’t wear loose clothing around moving equipment.
--Be aware of the product stream being repelled and be mindful of potential flying debris.
--Leave your cell phones, credit cards, and laptops in a locker.
--If you have a pacemaker or other medical device, consult your doctor and medical device manufacturer before operating magnetic equipment.
Magnetism and its effect on ferrous materials create some unique—and perhaps unexpected—hazards for those working with and around magnetic scrapyard equipment.