Refuse equals revenue for this steel mill
April 2012 - The byproduct accumulated as a result of day-to-day operations often is an afterthought. For steel mills, steel shards and coils usually are stuffed into large containers to be dealt with once overflowing, unavoidable and a safety hazard.
“When you go on a mill tour, you don’t see where they dump their garbage,” says a rolling mill day supervisor at a large U.S. steel recycler.
“Many mills have neglected the waste side of the business,” he says. “When you’re trying to look at competitors for innovative ways to operate your business, you don’t look at the backside and how you handle waste product—but you should.” It’s not the highlight of a process, but the scrap byproduct is valuable and can be financially viable.
“We recycle scrap steel. The bands we chop up, we reuse in our process,” says a high-volume recycler in the United States. “We send the scrap to the melt shop to be ladled and remelted and made into steel.”
However, waste management was not the primary reason the recycling company wanted a new scrap chopper. “It was actually a safety incident,” he says. “Like most steel mills, we have a lot of scrap bands that are thrown into bins. Well, the scrap hangs in the bin at all angles. A teammate walked by and cut his arm, so it got us thinking about how to eliminate these hazards.” Although the incident was a minor first-aid injury, the recycler viewed it as a reason to rethink the company’s processes.
Prior experience with Gold Hill, Ore.-based Sweed Machinery Inc. choppers at other mills prompted the recycler’s rolling mill day supervisor to look into getting a model from Sweed distributor J&B Container Co., Woodstock, Ga. The company purchased Sweed’s Model 517 XHD scrap chopper and achieved benefits in addition to safety.
The 5-horsepower drive motor has 1⁄2-inch plate-steel housing; a magnetic starter, which protects workers from an unexpected restart after loss of power; and air-activated feedworks, which a foot switch controls for additional operator safety. The material is fed into the infeed funnel and the feedworks (pinch rolls) grab the material and pull it into the rotating knife path. The feedworks continues to pull at a rate of 90 feet per minute until the material is consumed or the operator releases the air-activated feedworks using the footswitch, according to Sweed.
The recycler works with coated metal scrap banding material. “Pretty tough stuff,” adds the rolling mill day supervisor, noting the company rolls steel billets into coils. “These coils like to come uncoiled, so when we’re winding them up, we put metal banding on the outside to hold them together,” he says. “We used to put scrap in a much larger bin and had to empty it daily.” Since using the Sweed machine, the company switched to a smaller container and only needs to empty it once a week.
The shredded bands are reused in the company’s process and then sent to melt shops to be remelted and made into steel for production needs.
The Sweed machine condenses the scrap into more manageable pieces. Instead of huge, oblong, cluttered pieces of scrap, the chopper neatly cuts and stores the scrap for easy transport. “Think of a pad of printer paper,” the supervisor says. “If you took each sheet, wadded it up and tossed it into a wastebasket, it would overflow much quicker than if you placed the pile of flat, stacked sheets of paper. If you can cut in small pieces that lie flat, you can put much more material into a much smaller space.”
The easy storage segues into easy transport of the material. “Before, you were transporting more air than you were steel. In one bin using the Sweed chopper, you can carry the same amount as seven or eight large bins,” he says.
According to Tyler Casebeer, engineering manager at Sweed Machinery, customers often look to Sweed to help increase the value of scrap. “Scrap dealers will typically pay more for chopped product than non-chopped for safety and shipping cost reasons,” he says. “It’s easier for the people they sell to because the material is easier to manage.
“The material is reduced in size when reintroduced into the foundry system,” Casebeer continues. “If a scrap dealer were to get the scrap unchopped, they still have to get it in a chopped condition. Our machine basically eliminates that step so scrap dealers are willing to potentially pay more for it.” Casebeer adds the value to scrap dealers increases as volume increases.
Once collected, the recycler found the rolled materials frequently unraveled during transport. “Once it’s become unrolled, it is sharp and dangerous. It’s uncontrollable,” the rolling mill day supervisor says. “Try to bunch up a twisted slinky—when we take these metal bands, it runs through a chopper and is deposited into a container. Instead of dealing with jagged edges and falling pieces, the stacked materials are easily handled with a forklift.”
It is much easier to handle bands 1 inch wide by 4 inches long instead of “long, stringy bands,” he continues. “We’ve improved steel and our scrap people love it because it’s a lot easier to handle and more efficient to process.” Using the chopper simplifies handling of the byproduct produced by the recycler’s daily operations. “We’re a recycler. We take this byproduct, this waste, and use this piece of equipment to cut it into an easier-to-handle material that we can feed back into the beginning of our process,” he says. “We’d need to recycle it anyway, but the added benefit here is there are no losses. We’re able to utilize 100 percent of the scrap.”
According to Casebeer, there is a certain density scrappers need to reach to ready material for the foundry. “It’s much easier for foundries to deal with and reinsert the scrap if it is chopped. In [this] case, the steel banding, it’s not very dense if it’s not chopped.
“While people are generally initially drawn to Sweed machines because of safety aspects, they quickly realize another justification for using the machine is increased scrap value,” Casebeer continues. Situations differ from customer to customer, and it can serve as significant motivation to purchase a chopper if scrap value is important to the company’s bottom line.
The difficulty transporting the formerly tangled mess of scrap resulted in lost pieces. “The pieces would fall out of the bins or get caught under the ties of the fork lift or cut people’s tires because it would end up on the roads during transport,” the rolling mill day supervisor says. “When you cut it up into a more manageable form like this, it really makes a difference.”
Safety, the initial reason that fueled the recycler to change its processes, is increased greatly because the compaction of the material is unlike other traditional methods.
“Getting the scrap into the bins, dealing with it once it’s in the bin and then moving it is easier with a machine that makes the scrap smooth and compact,” Casebeer says. “Once it’s in the bins, [the recycler] no longer has to deal with tubed coil because it’s stacked, laid down and easier to handle.” MM