TECH TRAK Easier-to-digest ‘meatballs’ for finicky mini-mill melters

Oct 01, 2007 | 03:20 PM |

Meatballs go well with spaghetti or smothered with tomato sauce on a long Italian roll. They don't digest well in a steel mill's electric furnace, at least those served up with portions of shredded scrap.

The "meatballs" are copper armatures or parts of copper motors from automotive starters and alternators or the compressor motors in appliances. They are part of the shredded flow because most have a magnetic steel rod.

"The meatballs are still with the shredded because they have a steel shaft in the middle of the copper windings," explained Bobby Triesch, vice president of ferrous operations at Newell Recycling of Atlanta Inc. "Because that steel shaft is there, it jumps over to the magnet."

When a junked vehicle or appliance is shredded, the shredder's magnet picks up that steel shaft and with it comes the copper that some steel mills dread because it can harden their steel products, particularly flat-rolled sheet. That can make it difficult to form into parts like car hoods and doors. To counter that, most shredders have a picking line as the last pass before the shredded is dumped into a pile to be shipped to steel mills or loaded onto a boat for export.

Picking lines are manned by workers whose task is to spot the reddish color of the copper meatballs—hence the nickname—and remove them from the conveyor belt.

Copper wiring doesn't normally make it that far through the shredding process, unless it is bolted to a piece of steel or iron as a grounding wire. It normally drops into the nonmagnetic fluff, or shredder residue. Inshredders with additional downstream separation systems, it often is recovered and sold as nonferrous scrap under such ISRI specifications as Zorba or Zebra. Not to be outdone, the copper-laden meatballs, or shredder pickings, have their own ISRI spec Shelmo.....