Recycling sorting

At curbside many communities are collecting aluminum and tin cans, glass bottles, newspaper and plastic bottles. High-density polyethylene (HOPE) and polyethylene terephthalate (PET) are the most commonly recycled plastic bottles. Some areas that have a market for other plastics also pick them up for recycling. Sorting is done to some degree by the resident, the collector, and the reprocessor. 

NatureWorks LLC, Leading Recycler Sorting System Separates NatureWorks PLA from PET, press release, Jan. 24, 2005. 

Plastic recyclers sort the plastics by plastic type and then covert tbe recycled product into plastic pellets. The recyclers can also provide melt index and density measurements of the recycled plastic pellets to assist the plastic converter in using the recycled plastics to produce plastic bottles, bags, packaging, or other plastic products. 

Recycling of HDPE. Polyolefins, including HDPE, are the second most widely recycled thermoplastic materials after PET (110). A significant fraction of articles made from HDPE (mostly bottles, containers, and film) are collected from consumers, sorted, cleaned, and reprocessed (110—113). Processing of post-consumer HDPE includes the same operations as those used for virgin resins blow mol ding, injection molding, and extmsion. 

The initial step in the recycle of metals is the physical segregation of the metals from other materials. Eor new scrap this process is straightforward for old scrap it can be expensive. This classification and segregation of scrap is of importance to the producers of the metals from secondary materials. Historically, much of the classification has rehed on hand sorting which can be rehable, but it is labor intensive. The recycling of automotive scrap is illustrative of the... 

It is not tme either that vinyl is the problem in municipal recycling because it contaminates other resins. Contamination occurs whether or not vinyl is present. Other resins are just as much a contamination problem as vinyl. Except for commingled plastics apphcations, different plastic materials caimot be mixed successfiJly in most recycled products apphcations. This is why it is cmcial to separate efficientiy one plastic from another. Because of the chlorine that is present in it, vinyl lends itself very weU to automated sorting technology. 

The economic balance must be considered between recovery, reuse, and modification of a waste material or by-product and its disposal. The future is expected to bring iacreases ia the practice of recycle, recovery, modification, and upgrading of wastes of all sorts, and a reduction ia disposal by iaciaeration (qv), biochemical oxidation, or discharge to the environment (see Recycling). 

Manual Component Separation The manual separation of solid-waste components can be accomplished at the source where solid wastes are generated, at a transfer station, at a centralized processing station, or at the disposal site. Manual sorting at the source of generation is the most positive way to achieve the recoveiy and reuse of materials. The number and types of components salvaged or sorted (e.g., cardboard and high-quality paper, metals, and wood) depend on the location, the opportunities for recycling, and the resale market. There has been an evolution in the solid waste indus-tiy to combine manual and automatic separation techniques to reduce overall costs and produce a cleaner product, especially for recyclable materials. 

Prior to smelting, batteries are usually broken up and sorted into their constituent products. Fractions of cleaned plastic (such as polypropylene) case are recycled into battery cases or other products. The dilute sulfuric acid is either neutralized for disposal or recycled to the local acid market. One of the three main smelting processes is then used to reduce the lead fractions and produce lead bullion. 

Recycling of unwanted polymers is the best solution, and six types of plastics in common use are frequently stamped with identifying codes assigned by the Society of the Plastics Industry (Table 31.2), After being sorted by type, the... 

Poly(ethylene terephthalate) (PET) is one of the most extensively recycled polymeric materials. In 1995, 3.5 x 104 tons of PET were recycled in Europe.1 The main reason for the widespread recycling of PET is its extensive use in plastic packaging applications, especially in the beverage industry as plastic bottles. The consistency in terms of volume and availability of postconsumer bottles from sorting facilities and its high material scrap value create an excellent economic environment for PET recycling. 

PET has the second highest scrap value for recycled materials, second only to that of aluminum.1 A typical PET beverage bottle consists of PET (60 g), polyethylene (1 g), and label and glue (5 g). Therefore, the PET bottle scrap must be separated before the PET can be recycled. The bottles are sorted at a material recovery facility and compressed. The compressed PET bottles are then washed and converted to flake by grinding. The flakes may be converted to pellets in an extruder. The pellets are more suitable for material handling. Currently recycled PET is being used to make food and nonfood containers, straps, sheeting, and... 

On land, too, there are changes in the way plastics are disposed of. In the UK some local authorities are actively promoting recycling of plastic bottles and poly(styrene) containers, for example by schemes where local residents place recyclable materials in designated boxes for refuse collectors. These boxes are taken to a Materials Reclamation Facility for final sorting of the plastics waste. 

Separate collection of plastics, sorting, cleaning and mechanical recycling. 

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