Recycling has been embraced by engineers worldwide, and making the automobile ever more recyclable has become an engineering mantra. But there’s a potentially more effective subset in recycling for recovering value from vehicle end-of-life than total materials separation and re-use, according to Professor John Sutherland of Purdue University. It’s remanufacturing—something the auto industry has done in many areas, and which it can do even more effectively, he said. Remanufacturing even has potential for re-use of parts containing rare earth elements (REEs), he added.
Sutherland, whose background is in manufacturing and industrial engineering, described automotive remanufacturing as "a great way to be green and generate increased profit." He spoke at the recent remanufacturing forum during Automotive Aftermarket Industry Week in Las Vegas.
Although 95% of automobiles go into "recycling," that number does not refer to the percentage of the car that is recovered for other than scrap. Some percentage (based on market demand) of automotive mechanical and electromechanical components have long been rebuilt in small shops, and more recently been remanufactured in large plants.
REEs supply issues
Despite environmental concerns, some areas of value have been nearly ignored, or present a specific challenge. Among the most obvious are plastics, of which there are at least 20 different types in automotive use, Sutherland noted. If put in a shredder "they get mixed together," limiting their recyclability. Although there is no shortage of plastics, REEs are hardly in abundant supply, yet are key in engineering strategies for energy efficiency. REEs often are not recovered at all, he explained.
A major supply challenge is that China is the world's leading source of REEs, and its reliability as a supplier is often questioned. The REEs are not really rare, but the current mining and separation processes are difficult, expensive, and typically toxic. Although other countries have significant deposits, they have environmental regulations that make the materials effectively inaccessible, Sutherland said.
REEs magnets, he observed, are used extensively in motor vehicles, and the total in-use stock in all applications is about $5 billion, of which less than 1% will eventually be recovered at present rates. "The value likely is underestimated," he added, as "recycling may also recover other elements, such as iron and nickel."
REEs are used in lithium-ion batteries and in other components of electrified vehicles, so unless there are alternatives developed their availability is vital to meet clean-energy mandates, said Sutherland. Although nickel is a low-risk metal, there are others that fall into the near-critical and critical category, he added.
As a result, the challenges to REEs recycling must be faced, he told the forum. A leading one, he said, is collecting product that is set to be discarded. He said small amounts are used in so many areas, and there is no good information on the amount in different products. An exception, he said, is the hard disc drive, which uses significant amounts. Hitachi, he noted, had been spending 300 seconds to take apart HDDs, but developed a new cycle that reduced the time to 36 s—an 88% saving in labor cost. Difficulties that remain include REEs price fluctuation and unclear profitability of recycling. A related aspect of concern is that recycling is often done on a small scale, which results in a labor-intensive process.
If remanufacturing components or re-use of detail parts containing REEs is identified as a more cost-effective alternative to total separation for materials recycling, the product design itself would have to reflect the best possibility—that is, it should factor in a REEs mixture that not only is cost-effective for performance, but provides a clear choice for re-use in a remanufacturing application vs. material separation for re-use. Which adds to the importance of information on composition.
Design for disassembly
Other keys are design for dismantling and use of better equipment to expedite the process for whichever form of recycling is the choice.
Design for disassembly can promote value recovery, Sutherland said, and should start with simplicity of the cycle and physical ease of the way parts are separated. These should include reduction in the number of fasteners, greater standardization in fasteners used, and elimination of non-reversible connections where possible. Further, he suggested that the assembly/disassembly process itself should focus on reducing component complexity, combining components, and minimizing the variety of materials used.
Industry has developed effective recycling/remanufacturing processes for many automotive products, including those mandated by regulation. Because of the toxicity issue, the lead-acid battery industry employs a closed-loop process for recycling lead, and the recovery percentage is over 90% effective. All worn-out tires are subject to recycling fees when replaced. Some heavy-duty ones may be recapped, some shredded for use as fillers. But the majority goes for use as fuel, primarily in such applications as cement kilns, as burning tires creates very high heat, a Goodyear spokesman said. Precious metals in catalytic converters, particularly platinum and palladium, are recovered by smelting.
The REEs availability issue is not being ignored. The U.S. Department of Energy's Ames Laboratory in Iowa (specifically, its Critical Materials Institute) and the DOE's Energy Innovation Hubs are conducting a major research project. They are working with seven universities (including Purdue), and other national laboratories. Some 250 researchers are involved, Sutherland told the forum, looking for substitute materials. The critical ones are dysprosium, terbium, europium, neodymium, and yttrium; the near-criticals are lithium and tellurium. In addition to automotive, REEs are used in solar panels, wind turbines, and lighting.