Pebbles of ABS plastic are produced from the residue using Argonne's froth flotation process. Argonne National Laboratory photos. The process, now being pilot-tested, could unlock many valuable sources of plastic. The project, done jointly by Argonne researchers and those from the Vehicle Recycling Partnership, the American Plastics Council and the Appliance Recycling Centers of America, was the first successful test of using 100 percent post-consumer recycled material in an automotive application, according to Argonne lead researcher Ed Daniels.
Froth flotation allows two or more equivalent-density plastics to be separated with high purity.
The resulting products are of commercial quality and would be priced competitively with virgin materials, Daniels said. The froth flotation technique modifies the effective density of plastic materials as a basis for separating ABS and HIPS plastics. Controlling the chemistry of the forth selectively affects the surface characteristics of the different plastics. In this manner, small gas bubbles can be attached to one material's surface, reducing its effective density relative to other materials. Because of the lower effective density of the bubble-plastic particles, that plastic will float while the other plastics will sink in an appropriate solution.