The cement kiln process is one technology currently used for glass fiber recycling. That captures some of the material’s entrained energy, and the reclaimed glass fiber is used primarily for low-value cement filler. That’s better than sending the composite to a landfill but doesn’t provide the best economic incentives for recycling. Pyrolysis is another technology option, but previous attempts have not provided the right combination of recovered fiber strength and value.
Looking for a better solution, ACMA and Owens Corning, under the auspices of IACMI, are leading a collaboration of 12 industry and research partners in the development of a thermal composite recycling technology known as the Thermolyzer™. It is a controlled pyrolysis unit that uses the energy inherent in the composites to fuel the recycling process while preserving the structural value of both glass fiber and carbon fiber. Excess energy generated by the process might even help run other equipment in a factory or laboratory where the Thermolyzer is located.
The ACMA-led team will be using a Thermolyzer test unit located in Germany during a trial in March. It plans to recycle a variety of shredded composite materials – wind turbines, industrial scrap and automotive SMC – that contain both carbon and glass fibers.
“[For glass composite recycling] we have to look at pulling out fiber that has a length of greater than ½-inch so that it retains its strength and is not embrittled – it’s usable,” says Dave Hartman, scientific advisor, composites at Owens Corning.
“Once we have figured out how to get the fibers out economically, we are still going to need to develop applications using the recovered glass fiber,” Coughlin adds. The goal is to reach a commercially acceptable level of fiber strength suitable for reinforcement.
Since a continuous process runs most efficiently when it is operating 24/7, the composites industry could work with other industries, such as carpeting and electronics, which also have waste streams that need recycling. This would supply the equipment with the steady fuel stock it requires.
The project team will complete is work by December. While recycling GFRP won’t be easy, Coughlin believes the composites industry will find an answer. He cites the example of paper companies, which had to find ways to make the recycling of low-cost cellulose fiber work. The key was creating a market pull for the recycled products. The federal government helped when it specified the purchase of recycled paper. Commercial companies soon followed, creating demand for fiber recovery. The composites industry and their customers could create that same kind of market pull if they can develop the right applications for recycled glass and carbon fibers.