Fabric recycling

For many fabric recycling processes such as nylon depolymerization and polymer resin recovery, it is desirable or required to sort the feedstock according to the type of fibers. For carpet, the sorting is according to the type of the face fiber. A melt point indicator is an inexpensive instrument that can identily most fiber types, but it is generally slow and cannot distinguish between nylon 6,6 and polyester. Infrared and Raman spectroscopy are much more effective. Table 6.1 compares the various carpet identification systems. ... 

Polypropylene. Polypropylene (PP) is used ia packagiag appHcations as films and ia rigid containers. Battery cases could be considered another packagiag appHcation. Dead batteries are often collected at the poiat of sale of new batteries. In the U.S., some states have laws mandating this. Lead, acid, and plastics, particularly PP from battery casiags is recovered and recycled (3). Care must be taken to limit worker exposure to lead duting this process (44). PP is also recovered from bale wrap and other PP fabrics used for wrappiag ia the textile iadustry and from other containers (45). 

Most off-quahty or scrap polypropylene fibers may be repeUetized and blended in small percentages with virgin polymer to produce first-grade spunbonded fabrics. The economics are of great importance in a process where high yields are required in order to be competitive. Some manufacturing equipment direcdy recycles edge-trim back into the extmder where it is blended back into the polymer melt (see Fibers, olefin). 

As the recycled fuel composition approaches steady state after approximately four cycles (1), the heat and radiation associated with and Pu require more elaborate conversion and fuel fabrication facihties than are needed for virgin fuel. The storage, solidification, packaging, shipping, and disposal considerations associated with wastes that result from this approach are primarily concerned with the relatively short-Hved fission products. The transuranic... 

Uranium oxide [1344-57-6] from mills is converted into uranium hexafluoride [7783-81-5] FJF, for use in gaseous diffusion isotope separation plants (see Diffusion separation methods). The wastes from these operations are only slightly radioactive. Both uranium-235 and uranium-238 have long half-Hves, 7.08 x 10 and 4.46 x 10 yr, respectively. Uranium enriched to around 3 wt % is shipped to a reactor fuel fabrication plant (see Nuclear REACTORS, NUCLEAR FUEL reserves). There conversion to uranium dioxide is foUowed by peUet formation, sintering, and placement in tubes to form fuel rods. The rods are put in bundles to form fuel assembHes. Despite active recycling (qv), some low activity wastes are produced. 

Low molecular cationic polymers or alum can also be used to flocculate pitch, ie, bind up the pitch so that it is retained in the sheet, to minimize pitch deposition on machine surfaces and fabrics (35,36). Alum is used commonly in newsprint operations (34). The addition of a nonionic surfactant with a hydrocarbon solvent to the wet end has shown some utility in preventing deposits of adhesive recycled furnish contaminants from forming on the paper... 

Automobiles are the largest source of obsolete scrap. Other important sources of obsolete scrap include the demolition of steel stmctures and railroad companies. The latter provide a steady flow of scrap from their fabricating shops and from the recovery of worn out or abandoned track and railroad cars. AH iron and steel products are recyclable if economically retrieved when scrapped. 

Secondary Recovery. Metal returning from the store of metal in use is referred to as old scrap, in contrast with scrap generated within the copper fabrication process, which is called new scrap (see Recycling). In 1990 the amount of the U.S. copper supply derived from old scrap was 24% of the total copper consumed. About 40% of old scrap is used for producing refined copper most of the remainder is used in the production of brass and bronze ingots (see Copper alloys). About 75% of new scrap is consumed by brass mills, with most of the remainder used in the production of refined copper. Some estimates suggest that as much as 60% of the copper produced is ultimately recycled for reuse. Old scrap combined with new scrap from fabricating plants accounts for about 40% of the metallic input to domestic copper furnaces. 

Ultrafiltration membranes are commercially fabricated in sheet, capillary and tubular forms. The liquid to be filtered is forced into the assemblage and dilute permeate passes perpendicularly through the membrane while concentrate passes out the end of the media. This technology is useful for the recovery and recycle of suspended solids and macromolecules. Excellent results have been achieved in textile finishing applications and other situations where neither entrained solids that could clog the filter nor dissolved ions that would pass through are present. Membrane life can be affected by temperature, pH, and fouling. 

Develop a detailed process scheme for decolorizing recycle water used in a fabric dyeing operation. Assume the operation to be continuous. Develop a detailed list of all parameters that impact on the operation of a carbon filter. 

Reuse of waste metals generated from metal fabrication and from discarded products (scrap) can save large amounts of energy, particularly for metals that have high energy use in production, such as aluminum. The low fractions of energy used to produce metals from scrap for aluminum, certain sources of copper, and nickel show the value of recycling these metals. 

Bag molding Hinterspritzen This patented process allows virgin or recycled TPs such as PP, PC/ABS, etc. to thermally bond with the backing of multilayer PP based fabrics providing good elasticity. This one step molding technique provides a low cost approach for in-mold fabric lamination that range from simple to complex shapes. 

Recovery and reuse of synthetic polymers is by far the most acceptable way of dealing with the problem of waste. Items can rarely be reused as such but instead the polymers from which they are fabricated can be recycled. In principle, polymers can be recycled without any significant loss of their properties. For example, polycarbonate bottles can be recycled into automobile bumpers and then into articles for high performance housing. 

Journal of Coated Fabrics Vol.23, April 1994, p.274-9 RECYCLING OF PVC-COATED FABRICS... 

The trends in environmental research will be considered on the basis of polymers, fillers, oil, and other processing aids, reinforcing fabrics, other chemicals, and recycling technology. Broadly speaking, the following research trends are evident on a global scale ... 

Besides scrap and worn tires, other main sources of waste mbber are discarded mbber products, such as mbber pipes, mbber belts, mbber shoes, edge scraps, automobile hoses, and various fabric-reinforced components. Scraps produced during the production of mbber goods also contribute to recycle stream [6]. Reutilization of waste mbber demanded effective techniques for its recycling. 

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