Designing for recycling. (Scrap Industry News).

Scrap recyclers have been making a living for centuries, notes Len Shaw, executive director of the Canadian Association of Recycling Industries (CARI), but product designers can make the process more difficult when unwelcome materials are used.

Shaw spoke at a session sponsored by CARI at the Canadian Solid Waste and Recycling Expo late last year in Toronto. He cited the presence of airbags, mercury switches and non-recyclable plastics as hindrances toward full end-of-life vehicle recycling.

Mercury switches, by volume, are a minor contaminant in the scrap metal stream, but any traces of mercury emitted by the mills and smelters that consume scrap metal are unwelcome. Shaw noted that automakers are finally committing to stop using mercury switches, which can often be found in the trunks and glove compartments of vehicles.

Airbags--though lauded as a safety feature--contain a carcinogenic chemical that can make its way into scrap and shredder residue streams. Additionally, airbags can pass through auto shredder units without exploding, becoming "little bombs" when they arrive at aluminum smelters, according to Shaw.

Because North American governments like airbags as a safety feature, "now automakers are looking at designing cars with up to 14 airbags," Shaw remarked.

While metals recycling may be centuries old, plastic recycling is less established. "It's tough to make commingled plastics [found in autos] into something--especially if they are contaminated with paints and solvent," noted Shaw.