New Recycling Process for Mixed Waste Plastics
The University of Edinburgh's Department of Chemical Engineering is helping to develop the first, demonstration-scale polymer recycling plant, which may be sited at Grangemouth. Intended to process the plastic waste from Glasgow and Edinburgh, the plant will also deal with local manufacturing waste.
Project supervisor Dr Don Glass explained: "Waste plastic, particularly packaging, is one of the curses of the industrial age. Ill-managed landfill sites are surrounded by large areas in which unsightly wind-blown polymer film is festooned on trees and fences." He added that current EU regulations mean 15% of waste plastic must be recycled, but hygienic and safety considerations prevent the re-use by melting and re-forming, of the huge quantities of plastics used as food packaging.
"A process developed by an industrial consortium, led by BP Chemicals Ltd, converts mixed waste plastics from municipal and industrial waste into a heavy liquid, suitable for use either as petroleum feedstock or in producing ethylene and propylene, the building blocks of much plastics production," said Dr Glass. "This is done by breaking up the large polymer molecules under the influence of heat in a fluidised bed - equipment in which a powdered solid is induced to behave like a liquid by upward patterns of gas flow. The product is a viscous, waxy liquid."
The School of Chemical Engineering has contributed to the development of this process over a number of years, particularly in studies of the best way to transfer to the fluidised bed the heat necessary for the depolymerisation reaction.
The 12-month project is being funded by BP Chemicals Ltd (£10,000) and the Engineering and Physical Sciences Research Council (£51,350). An accurate scale model of the proposed reactor vessel will be used to investigate the design of a gas distributor for the bed, and the movement of polymer particles within it.
For further information, please contact:
Dr Don Glass, Tel: 0131 650 4860