Mixed plastics waste recycling

Section 3 discusses options for feedstock recycling of mixed plastic waste ... 

Concerning feedstock recycling of mixed plastic waste (MPW) with a low chlorine content, the following initiatives seem to be most promising. They are either operating in practice, have operated in the past, or have a fair chance of becoming operational in the short-term. Methods include ... 

Feedstock recycling is examined as a method of plastics recovery. The range of techno logics currently employed are described, and include pyrolysis, hydrogenation, gasification, and chemolysis. Methods for the recycling of mixed plastics wastes are discussed, which include work by BP Chemicals, VEBA Oil, Shell Chemicals and Leunawerke. 

An account is given of the chemical recycling activities of BASF in a pilot plant at Ludwigshafen in Germany, where mixed plastics waste is processed to obtain hydrochloric acid, oil, gas, naphtha, aromatics and alpha-olefins. 

The BP-led feedstock recycling consortium recently unveiled its new larger-scale fluidised bed pyrolysis pilot plant, located on the BP refinery site at Grangemouth. The 2 tonne/day plant will take mixed plastics waste from a variety of sources to provide more extensive trial results, to be used in the conceptual design of a 25,000 t/y semicommercial demonstration plant. The consortium envisages a series of plants, of around 25,000-50,000 t/y, scattered across Europe. 

Current methods of feedstock recovery are reviewed. Brief details are given of pyrolysis, hydrogenation, gasification, and chemolysis. Activities of some European companies are briefly discussed in the areas of recycling mixed plastics waste and closed-loop recycling. 

Most polymer products are offered for recycling in the form of mixed plastic waste (MPW). Compressed gases as solvents may offer advantages compared with liquid solvents in the necessary separations (e.g., to collect families of polymers out of MPW) because such solvents are easy to recover and, furthermore, they make it possible to use pressure as an additional separation parameter or to remove the organic additives of the polymers. Finally, MPW may be added as a polymer solution in a compressed gas to a feed of a Naphtha cracker, and thus be recycled to base chemicals. 

Tall S (2000) Recycling of mixed plastic waste—Is separation worthwhile PhD Thesis, Royal Institute of Technology, Stockholm, Sweden... 

Feedstock or chemical recycling is seen as complimentary to mechanical recycling and seems appropriate for cost effective treatment of mixed and contaminated plastic waste streams (115). A progress report, on potential technologies for high PVC content mixed plastic waste streams, is available (21). Promising developments, which look technically and economically viable, are ... 

The PVC industry is actively involved in the development of recycling solutions for contaminated mixed plastics waste streams with a high PVC content. Potential technologies for achieving this goal are tested at present at pilot scale. This paper provides an overview of the projects under investigation and the results obtained so far, while development work continues. 9 refs. 

The detailed analysis of the derived oil/wax and gas products from the pyrolysis of plastics in relation to process conditions and different types of plastic is essential in providing data for the assessment of the feedstock recycling process. In addition, the yields and composition of gases and oils from the pyrolysis of mixed plastic waste are important in assessment of the process and to determine the possibility of any interactions between the plastics during pyrolysis. 

TECHNOLOGIES FOR TERTIARY RECYCLING OF MIXED PLASTIC WASTE (MPW)... 

W. Kaminsky and H. Sinn, Pyrolytic techniques, In Recycling and Recovery of Plastics, J. Brandrup et al. (eds), Hanser Publishers, New York, pp. 435-444, 1996. W. Kaminsky, B. Schiesselmann and C. M. Simon, Thermal degradation of mixed plastic waste to aromatics and gas, Polymer Degradation and Stability, 53, 189-197 (1996). 

Some of the procedures of value for processing of mixed plastic wastes may also be useful for the recovery of value from the laminates used for efficient packaging of food and beverages (e.g., milk cartons, Tetrapaks). A combination of heat and pressure may be employed on a recycle stream of this type of material to fuse the mixed fibrous and resin components into a dense board-like product [31, 32]. This highly weather and insect resistant product, Eco Superwood Plastic Lumber, may be sawn, nailed, drilled, etc., like wood, and it resists rotting in direct contact with the soil without the need for preservatives. 

Figure 11.12. Dehydrochlorination rate of PVC with and without 10% calcium carbonate. [Adapted, by permission, from Braun D, Kraemer K, Recycling of PVC Mixed Plastic Waste, La Manta F P, Ed., ChemTec Publishing, Toronto, 1996.]...

Braun D, Kraemer K, Recycling of PVC Mixed Plastic Waste, ChemTec Publishing, Toronto, 1996. 

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