Upgrading zorba to reach a 98 percent nonferrous metallic was the focus of a session at the 2015 Institute of Scrap Recycling Industries Inc. (ISRI) Annual Convention, held in April in Vancouver, British Columbia, Canada.
Tim Shuttleworth, CEO of magnetic equipment maker Eriez, Erie, Pennsylvania, said a challenge for auto shredder operators has been that when producing a zorba product at 98 percent purity “you [subsequently] lose product to the waste stream.” He summed up the dilemma this way: “When you push for a higher grade, you can lose volume. When you push for the highest total recovery, you produce a less valuable grade.”
He remarked, however, that China has a regulation on the books that it can enforce at will stating that zorba entering its ports must meet the 98 percent purity threshold. In addition to that, Shuttleworth asked recyclers, “Why do you want to ship 10 percent of your weight as trash?” when sending a 90 percent pure product to recipients?”
Eriez’s recycling equipment branch has been working with researchers within the Eriez mining equipment division and Virginia Tech University, Blacksburg, Virginia, to produce a 98 percent pure zorba product that does not allow marketable metals to slip through. “We’ve been applying science for years to move the [recovery] curve,” stated Shuttleworth.
Virginia tech Graduate Research Assistant Scott Koermer described the sequence or circuit of eddy current separators that makes up the Erie Rougher-Cleaner-Scavenger (RCS) system, which has been designed to improve purity without allowing metals to be lost to the waste stream. “Separation can be greatly improved using multi-stage circuits,” Koermer stated.
Testing conducted jointly by Eriez and Virginia Tech created a zorba product at a 99 percent purity level that jointly created a waste or residue stream that contained 1.2 percent metallic content, according to Koermer.
Shuttleworth told attendees the RCS system has been tested thoroughly by Eriez and the first plant-scale circuit is now being installed downstream of an auto shredding plant operated by Timken Co./City Scrap & Salvage [http://www.akronscrap.com/] in Akron, Ohio.
The 2015 ISRI Convention & Exposition was at the Vancouver Convention Centre April 21-25.