Nylon suppliers take lead in carpet recycling

Thanks to the efforts of nylon manufacturers, carpet recycling is on the verge of becoming a major plastics-related success story. Many companies are now proving that closed-loop recycling of nylon carpet will work given the proper infrastructure for collection and the right products.

DuPont has recently announced plans to build a demonstration plant in Maitland, Ont. for the recycling of nylon 6,6 and nylon 6 carpet, as well as other post-consumer nylon waste. The unit, which is a scale-up of a pilot plant in Kingston, Ont., will transform the nylon waste into hexamthyldiamine (HMD), adiponitrile and caprolactam.

According to DuPont, one major objective of the demonstration plant will be to prove that the quality of the recycled product is equivalent to virgin nylon. Another goal is to make the HMD recycling effort cost competitive to DuPont’s method for making HMD from adiponitrile starting with virgin product.

As with other types of plastics recycling, the ultimate cost often depends a great deal on the logistics of collecting, sorting and pre-processing. DuPont Flooring Systems runs a network of about 80 outlets in the U.S. that install new carpet and reclaim old carpet. The old carpet is shipped to a facility in Tennesee that strips the carpet fibre from the backing and grinds it into nylon fluff.

Evergreen Nylon Recycling, a joint venture between DSM and Honeywell (formerly AlliedSignal) started an $85 million commercial-scale, closed-loop recycling plant in Augusta, GA last year. Evergreen plans to extract about 100 million lb. of caprolactam from 200 million lb. of carpet each year. The caprolactam will be shared equally between DSM and Honeywell in the manufacture of nylon 6.

Unlike DuPont’s current system, Evergreen does not have to strip the nylon fibre from the carpet backing before using. Instead, the company feeds whole carpet into the reactors. Polypropylene and latex backing, and the calcium carbonate filler, are left behind in the reactor as a residue which the company then ships to a cement kiln for incineration.

BASF and Rhodia have also launched carpet recycling initiatives. BASF converts post-consumer carpet made from its own Zeftron nylon 6 into caprolactam at a facility in Arnipor, Ont. At present, BASF depolymerizes about 20 million lb. of its own nylon waste each year, according to the company. Rhodia depolymerizes nylon 6 waste at three European plants with a total capacity of 65 million lb.