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How Car Bodies Are Recycled

July 1, 2012

The business of recycling cars is a multi-billion dollar industry that is crucial to the steel and automotive industries. But just what type of journey does an automobile take until it ends up as another car or truck?

Auto Salvage Dealers

This is where the recycling process for the automobile begins. Most end-of-life vehicles (ELVs) begin their journey at vehicle dismantling facilities where they are picked through for usable parts that can be resold or re-manufactured. To further prepare the vehicle for recycling, other items like batteries, tires and gas tanks are removed. All engine fluids are properly drained, stored and recycled, as well as refrigerant gases from air conditioners. Once these have been removed, the remainder of the car can be flattened, for space conserving reasons, and delivered to a scrap dealer.

The Scrap Yard

The flattened crushed automobiles arrive where they are weighed and unloaded. Next, they enter a shredding process where the remaining material is separated into three streams: iron and steel, nonferrous metal and non-metallic scrap. The iron and steel, both of which are highly recyclable, are magnetically separated from the other materials and recycled. Non-magnetic metals then can be forced to act magnetically by inducing electric currents known as “eddy currents.”

The remaining non-metallic scrap, known as “shredder residue” or “fluff”, is sent to landfills. This shredder residue typically consists of a mix of materials including polyurethane foams, polymers, metal oxides, glass and dirt. For each ton of metal recovered by a shredding facility, roughly 500 pounds of shredder residue are produced – about 4.5 million tons per year in the U.S. – are not presently being recycled.

The Shredder

The U.S. houses about 200 shredding facilities nationwide. The shredding process shreds the crushed cars and other metal goods into smaller pieces of various materials. These machines are very large and have powerful motors that drive rotors that spin hammers up to 175 miles per hour, which then demolish the cars into fist-sized metal chunks or smaller. The feed material can enter these hammer mills in either a dry, wet or damp condition and often at remarkable speed of one car every 45 seconds.

The Final Leg

The iron and steel then is shipped to end markets or steel mills where it is recycled to produce new steel. The same holds true for much of the other non-ferrous metals. Contemporary technologies produce new steel from old steel in two ways, the basic oxygen furnace (BOF) and the electric arc furnace (EAF).

The BOF process uses 25 to 35 percent old steel to make new. It produces products whose major required characteristic is drawability:

  • Automotive fenders
  • Encasements of refrigerators
  • Packaging (like soup cans)
  • Five-gallon pails
  • 55-gallon drums

The EAF process uses more than 80 percent old steel to make new. It produces products whose major required characteristic is strength:

  • Structural beams
  • Steel plates
  • Reinforcement bars

View the full article at Earth 911

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