Eriez finds the value in ashes

Energy recovery processes for discarded materials take many forms, including mass burn waste-to-energy (WTE) plants and the processing of municipal solid waste (MSW) and commercially generated waste into refuse-derived fuel (RDF).

In WTE and RDF applications, magnetic equipment from Eriez can play a vital role in harvesting marketable metals from the inbound or residue streams attached to these processes. Decades of experience have helped Eriez identify and customize the right equipment for these tasks.

Eriez Heavy Industries Market Manager Darrell Milton says at RDF plants, inbound material is treated preburn via shredding, screening and metal separation. He says, “In this case, Eriez can provide a magnetic separator for the ferrous material recovery and an eddy current separator for the nonferrous metals recovery.”

The combination, Milton says, “results in a very high metals separation efficiency.”

Harvesting metals from the ash produced by WTE mass burn plants involves different techniques as the material is vastly different in size and composition from the MSW brought into RDF plants.

Even in parts of the country with active recycling programs and an established scrap metal sector, Milton says WTE operators find that approximately 3 percent of WTE ash consists of iron-bearing materials. “Although the value of metals recovered from bottom ash does not quite equal shred value from an automotive recycling facility, the price of steel is approaching all-time highs, and there is a significant profit to be seen,” he says.

An Eriez eddy current separator (ECS), meanwhile, can harvest nonferrous metal fragments and fines. Suspended cross-belt magnets can be used to recover ferrous from bottom ash, but Milton says, “Eriez feels the best-suited magnetic separator in this application would be a large diameter magnetic drum separator due to minimal maintenance requirements while still offering a very high percentage of ferrous recovery.”

In particular, the P-Rex permanent magnetic drum can be the right one to tackle this job. “Eriez’s introduction of the P-Rex magnetic drum into the WTE market has provided our customers a significant increase in ferrous metal recoveries, in some cases over a 50 percent increase,” he remarks. “The drum does not lose strength due to heat rise after startup as seen with electromagnets and offers a wider magnetic field, ensuring the full width of burden is covered by the strong magnetic field.”

The P-Rex’s ability to harvest iron and steel can provide a revenue stream to WTE operators and municipalities, and it’s the right thing to do, Milton says. “Every pound of metal recovered is not being sent to landfill, which also carries an expense both socially and economically.”

For more information on the Eriez P-Rex in WTE applications, visit www.eriez.com/WTE.