Feedstock recovery

The different recovery options available for plastics waste might be summarized as follows  

The products are recovered from the MS W stream via curbside collection, separated/ sorted at MRFs, and then cleaned and ground into chips at plastic reclaiming facilities to be remelted into recycled resin pellets. The recycled resin is used, mixed with virgin plastics, in the fabrication of plastic products. Mechanical recycling works best when applied to source-separated streams of waste plastics products. 

Waste plastic is changed by heat or chemical agents into chemicals that might be used in the production of new polymers or as general chemical feedstocks (Al-Salem et al., 2010). Monomer recovery works well with source-separated plastics whereas general feedstock recovery is better suited for mixed plastic waste. 

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The largest use of NMP is in extraction of aromatics from lube oils. In this appHcation, it has been replacing phenol and, to some extent, furfural. Other petrochemical uses involve separation and recovery of aromatics from mixed feedstocks recovery and purification of acetylenes, olefins, and diolefins removal of sulfur compounds from natural and refinery gases and dehydration of natural gas. 

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. 

Low-temperature pyrolysis for feedstock recovery 500-600 Single or mixed polyolefins (HDPE, LDPE, PP, PS, PVC), SB rubber Nitrogen liquid-free pyrolysis gas Broad spectrum of products (C1-C50). The gas yield is generally low with respect to waxes and oils [9, 14, 16, 26, 27, 28]... 

High -temperature pyrolysis for feedstock recovery 650-800 Polyolefins (HDPE, LDPE, PP, PVC), SB rubber, ABS, PA, PTFE,. .. Nitrogen steam Gas yield is generally high High content of olefins [8, 9, 16, 19, 28, 29, 30, 31]... 

In the United States, landfill disposal still accounts for the majority of MSW and therefore for plastic waste as well. Mechanical recycling and incineration (waste to energy processes or WTE) are also in use, but to a much lesser extent. In Europe, whatever is not recycled is mostly incinerated for energy recovery. Feedstock recovery, though an attractive option, is not practiced as a laige-scale MSW treatment option. Figure 9.5 summarizes the available technical options for recovery of plastics waste. 

Selected chemolysis processes for PET are illustrated in Figure 9.8 and tabulated in Table 9.6. These reactions yield either the original monomers or products that can be converted to other monomers. Hydrolysis can be effectively used with PET and polyurethane waste plastics in feedstock recovery (Zia et al., 2007). Reaction conditions employed are varied and these selected references do not cover them exhaustively. Aromatic polyesters, PET and poly(butylene terephthalate), have been studied intensively for feedstock recovery. PET is extensively used in soda bottles and less than 30% of the product is mechanically recycled. 

Feedstock recovery via gasification/pyrolysis is an attractive option as it is not carbon emitting and yields valuable feedstock chemicals and/or fuels. The carbon in... 

Recycle should cover mechanical recycle in the originally intended application or in a downgraded application, or feedstock recovery with or without bromine recovery, or energy generation with at least the bromine recovered. 

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