Process Economics Program Report 199A
Plastics Reclamation and Recycling 199
Published: August 1995
In industrialized countries, the business of collecting and processing postconsumer plastics continues to grow, with increased amounts of plastics being handled, and a greater variety of plastics targeted for recycling. Companies that make virgin plastics are becoming increasingly involved in plastics recycling. Durable plastics items, as well as packaging, are being recycled in increasing quantities. New methods have been introduced for identifying used plastics by color and type and efficiently separating them from other materials. New applications for recycled plastics (and blends that include recycled plastics) are being developed. Mixed waste plastics are being processed into new polymer products and are being converted into chemicals and fuels, which is more desirable than merely burning them for energy recovery. Landfill is used as a last resort.
Disposable packaging is the largest single category of materials now being recycled. This category includes plastic bottles, plastic bags, shrink-wrap film, stretch film, blister packs, and foamed cups. Polyolefins, especially low-density polyethylene (LDPE and LLDPE) are widely used in film and bag applications. Both PET and PVC bottles are being reclaimed. Foamed cups and trays, primarily polystyrene, are reclaimed, but the reclamation rate is growing slowly.
Durable plastics are also being recycled. The polypropylene cases of automotive lead-acid batteries are being reclaimed and used for making new battery cases. Thermosetting resins are increasingly being reground and used as filler in new resin applications.
The recycling business may be divided into several components--collection and sorting, cleaning and reprocessing, and blending and marketing. Collection of postconsumer plastics has been largely the province of municipalities. Segregation of individual plastics has been done by householders, but automatic sorting now makes it possible to recover plastics from mixed solid waste (MSW). Development of processes and machinery for cleaning and reprocessing used plastics, done earlier by small inventors, has for the most part been taken over by larger firms. Blending and marketing are being done increasingly by the makers of virgin polymers.
This report evaluates a process for recycling postconsumer polyethylene film, another for processing PVC bottles into a polymer blend for making new PVC bottles, and a third one to convert mixed plastics waste to syngas. Information on new developments in recycling PET bottles and HDPE milk jugs is presented, along with brief descriptions of processes for recycling other plastics materials.
Plastics that cannot be easily separated by type are being processed as mixed plastics waste. Some of this material is suitable for making plastic lumber. Among new developments is the conversion of mixed plastics waste to gaseous and liquid products for chemical manufacture.
As an example of the conversion of mixed plastics waste, the report includes evaluations of three variations of a partial oxidation process for making syngas (useful for methanol and ammonia manufacture, among other uses).
Intended to help companies assess the impact of these developments on their own operations, this report will be especially useful to companies that are seeking a niche that complements their own plastics operations. Companies already engaged in various segments of the plastics recycling business will find it useful for assessing expansion opportunities.