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Counting on smarter analyzers and full-box shredding


Shredder operators are taking some high-tech steps to improve the quality of their shredded scrap.

The first is the Gamma-Tech Crossbelt Metal Analyzer, which has nothing to do with the actual tearing apart of metals. It's a process control device—an inspection machine that tells the shredder's operator what percentage of copper is mixed or alloyed with the ferrous metals.

Copper is a metallurgical problem for steelmakers, especially those producing flat-rolled steel. Copper hardens the steel, making it more difficult to shape and form into parts for automobiles and appliances.

The Gamma-Tech, installed below the conveyor line, uses a radioactive isotope that bombards the scrap with neutrons and looks at the chemical composition of the shredded scrap in a set of detectors above the conveyor, according to Joseph Pflaum, president of Gamma-Tech LLC and one of the developers of the analyzer.

By shooting a beam through the shredded material, the analyzer sees not only loose copper in the form of motors, wires and tubing, but also copper that is alloyed to the steel, Pflaum said.

The analyzer was introduced to the scrap industry about six years ago and has gained a number of advocates among industry managers. Pflaum, a metallurgist, said the technology has been used since the mid-1980s in the coal and cement industries. He was first introduced to it in the past decade when he worked for David J. Joseph Co. (DJJ). At that time, he was looking for something to give an analysis—any kind of analysis—of the metal.

DJJ's River Metals Recycling LLC was the first to install a Gamma-Tech analyzer at its shredder in Newport, Ky., in 2002 and has since installed analyzers at its shredders in Louisville and Henderson, Ky. Trademark Metals Recycling LLC, another DJJ company, installed an online bulk analyzer at its shredder in Tampa, Fla., in 2005. Sims Metal Management Ltd. also has added Gamma-Tech analyzers to several of its shredders.

The analyzer allows both shredder operators and steel mills to detect just how much copper is in the shredded. The mills, in determining whether they are using obsolete scrap efficiently, might have to dilute it with the addition of iron ore-based substitute materials, such as pig iron or hot-briquetted iron.

Another step aimed at producing higher-quality shredded sounds more like a simple change in operating practices, but it also includes some new technological gear.

Full-box shredding is designed to both increase the density of the shredded steel scrap and separate more of the nonferrous metals from the ferrous material, said Tim Conway, vice president of business development at San Antonio, Texas-based scrap equipment maker Metso Recycling North America.

While shredding of vehicles can tear them apart into fist-sized pieces of metal, Conway said some of those pieces can be two feet long and have chunks of nonferrous metals attached. "By shredding components and trimmings into a smaller, more dense package, we tend to clean up the scrap better," he said.

The concept calls for keeping the shredder box, the heart of the shredder, as full as possible so that not only the hammers but also the pieces of shredded metal work to break the material into smaller pieces.

Many shredder equipment makers and component suppliers have promoted the concept of full-box shredding, but Conway believes Metso "has a leg up" on its rivals.

"(Our) auto pilot drives full-box shredding. Everyone in the market has copied this but none have truly understood that it's not just a function of trying to equalize the shredding on the shredding motor. It's more a function of being able to understand how full the box is," he said. "So if you're shredding based on the amperage of the motor and the peak load is, say, 600 amps .?.?. full-box shredding may mean you want to run at 800 or 900 amps for a while to get the box completely full."

By breaking the metal into smaller prices, full-box shredding separates more of the nonferrous from the ferrous, thus cleaning up the ferrous portion and enabling the air-separation systems and other downstream equipment to recover the more-valuable nonferrous metals.

Full-box shredding doesn't mean shredder operators have to pile cars on top of each other and feed them into the machine's maw. It requires the operators to have the ability to control the shredder plant, not just running out and turning it off but being able to compensate for feeds and speeds, he said.

Smaller, older shredders might be hard-pressed to adopt the full-box shredding technology because they have few process controls, but the operators of the bigger heavy-duty and megashredder models can avail themselves of its benefits, Conway said.

"It's not counter-intuitive to the shredding operations," he said. "If they are bigger shedders, they have more horsepower. Just because it is a bigger shredder and more horsepower doesn't change the philosophy of properly shredding."

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