No easy task

Automotive shredder residue, or ASR, is the “fluff” that is left over after most of the metals have been extracted downstream of an automobile shredder. Much of this material is plastics—valuable plastics.

“Plastics are several times more valuable than steel,” maintains Mike Biddle, founder and president of MBA Polymers, headquartered in the United Kingdom.

He adds that more plastics are consumed—on a volume basis—than steel.

Yet, he says, while roughly 90 percent of metals are captured and recycled at end of life, only about 5 percent of the plastics that are produced are recycled. He cringes at the miniscule amount of plastics recovered for recycling. “We see landfills as above-ground mines,” Biddle adds.

Much of the plastic that is not recovered for recycling is incinerated or landfilled, and he maintains that is simply wrong—environmentally and economically.

For these reasons, it makes sense to recover the plastic fraction of ASR for recycling; but, getting there is a challenge.
 

Uncertain direction

“Most shredder operators do not have a clear vision where they want to be in five years,” observes Heiner Guschall, managing director of Sicon GmbH, Germany. The company’s U.S. division, Sicon America, is based in Alpharetta, Georgia.

“A lot of investments are done without such a vision, and plants are designed around a single machine,” Guschall says. “This is the wrong approach.”

Sicon designs modularized plants that can be expanded to improve the quality of the end product. Without this flexibility, he says, ASR processing becomes expensive and uneconomic.

“Plants need to be flexible in relation to final product quality,” Guschall says. “Markets are changing, and shredder operators need to be able to adjust to the needs of the markets.”

In fact, a variety of end markets, ranging from energy recovery to recycling, are available for operators considering processing ASR. (See the sidebar “Deciding on an Approach,” which is available at www.RecyclingToday.com.)

However, sorting plastics from ASR is not without its challenges. “Only 25 to 30 percent of ASR is plastics,” Guschall says, “and unfortunately the major portion is black, so NIR (near-infrared) separation does not work.”
 

Inside MBA

MBA Polymers appears to be ahead of the curve when it comes to recovering plastics from ASR.

Biddle says the MBA recycling process produces a plastic pellet that is cheaper than virgin material, provides an energy savings of 80 percent compared with virgin plastics and can be produced in facilities that cost tens of millions of dollars rather than hundreds of millions of dollars—facilities that produce many types of plastics, not just one.

“This is the last frontier of recycling—and we found how to do it,” Biddle says.

MBA sends incoming ASR through a fairly standard sieve, magnet and air classification process to remove most of the nonplastics, leaving a batch of mixed plastics of varying resin types and colors.

That material is ground and sorted by type, Biddle says, producing multiple streams of a single type of plastic.

Next, the individual resin types are optically sorted by color, and each individual product is blended in a 50,000-pound silo.

MBA then melts the material in extruders and runs it through small-diameter dies, producing a strand of plastic that looks like a long piece of spaghetti. Those strands are cut into pellets and sold to manufacturers, completing the process.

MBA says its twin-screw compounding technology lets the company tailor products to meet specific needs. MBA’s largest plant, which is in Worksop, Nottinghamshire, U.K., has an initial processing capacity of 60,000 tons per year, which can be expanded to 80,000 tons annually.

MBA says it believes it is the only plastics recycling company in the world sourcing ASR for 100 percent of its feedstock, turning plastics-rich residue into new high-impact polypropylene (HIPP), filled PP, ABS (acrylonitrile butadiene styrene), HIPS (high-impact polystyrene) and HDPE (high-density polyethylene).
 

Under the hood at VW

Sicon jointly developed a patented preprocessing solution for ASR with Volkswagen Group, Wolfsburg, Germany.

“We split ASR into a shredder fiber fraction, which is free of metals as a consequence of the intelligent liberation; a shredder sand fraction; and a plastic, wood and metal-rich fraction,” Guschall says. Sicon refers to this latter fraction raw shredder granules.

The raw shredder granules then enter a refining step, where more than 99.8 percent of the remaining metals are separated, Guschall says.

Plastic separation is an additional processing step. “ASR plastics are difficult,” Guschall adds.

The company uses two approaches for ASR plastics. One is dry separation of PVC (polyvinyl chloride) using the VariSort X, which employs X-rays to sort material. The second is wet separation of PE (polyethylene)/PP, PS and ABS using Polyfloat, which can separate plastics smaller than 1 millimeter in size.

Two plants in France are producing plastics for recycling using the Polyfloat system, Guschall adds.

Optionally, ASR can be processed using the Sicon (A)SR PTS crusher in the Sicon-100plus system, which the company says improves the metal recycling rate, while the nonmetallic materials recovered are of a quality that facilitates recycling.

Sicon uses the VariSort WEEE from Sesotec to separate printed circuit boards contained in the ASR to create a separate metal product.

Using the VariSort equipped with NIR sorters, plastics are sorted into concentrates by type, or they are sorted using a combination of cascading density separation with upstream electrostatic separation into pure PE (polyethylene), PP, filled PP, PS and ABS, the company says.
 

Energy recovery

However, if it proves too difficult or expensive for some recyclers to extract plastics from ASR for recycling, energy recovery options exist.

Based in Nottingham, U.K., with U.S. offices in Cranford, New Jersey, Chinook Sciences has successfully developed an advanced thermal treatment (ATT) system that recovers metals and generates energy from a wide variety of waste materials. Its operation in Oldbury, U.K., is the world’s largest industrial waste gasification plant and the first dedicated ASR recycling and energy recovery facility.

The Oldbury facility was developed in partnership with European Metal Recycling and can process more than 160,000 metric tons of recycling residues per year. In addition to generating electricity, it can recover up to 10,000 metric tons of metal for recycling, the company says. (More information on the Oldbury facility is available at www.RecyclingToday.com.)

Martin Nye, who manages development of Chinook Energy’s European business and is responsible for strategic direction and management of joint ventures, says, “One of the more difficult wastes to process is the residue from automotive recycling operation because it contains a wide variety of materials from cars and vans, as well as other postconsumer goods, such as refrigerators and washing machines.”

“ASR accounts for 25 percent of the original weight of the car being recycled,” he notes. This material consists of metals that cannot be salvaged easily using downstream sorting equipment, along with other materials, such as plastics, foam, glass, aggregates, wood, fabric and rubber.

Chinook Sciences’ RODECS system, its ATT technology, recovers valuable recyclables from ASR and generates more than one megawatt of clean, green energy from a typical metric ton of residual household or commercial waste, according to the company.

Chinook Sciences’ RODECS system was recognized at the annual Energy Institute Awards in late 2014.

The technology generates up to 100 percent more energy per metric ton of waste than conventional incineration, Nye says.

Chinook’s RODECS technology involves a combination of gasification and pyrolysis.

“The system is protected by more than 120 patents and is widely considered to be the world’s leading advanced energy-from-waste system,” Nye says.
 

Moving forward

Guschall, too, is bullish on gasification as an end-of-life option for ASR plastics. “We see a clear market for the conversion of plastics into gas and oil via gasification and depolymerization,” he says.

However, Guschall adds that today’s technologies are hindered by the poor quality of incoming material. Sicon is working to correct this by producing what he terms “design fuels” to meet exactly the needs of such plants.

“There will be a market for mechanical recycling as well as high-grade conversion,” Guschall says, adding that he does not see a long-term future in the incineration of ASR.

Regarding the recovery of metals and plastics from ASR, he says, “The scrap industry is at the moment not in the best mood.” But, he says he sees significant interest in finding a solution for recycling nonmetallics from ASR.

“It always depends on local markets. Not all plastics can be recycled—only a rather small portion,” Guschall says.

“A lot of preprocessing steps are simply inefficient and focus more on the separation of metals but not on the nonmetallic residue,” he adds.

“To recover the whole quantity of plastics from ASR will require more than just recycling of PE and PP.”

He adds, “There will be an economic balance of some mechanical recycling and feedstock recycling for blast furnaces or depolymerization,” Guschall concludes.

The author is a contributing editor to Recycling Today and can be contacted at curt@curtharler.com.