Process scrap

In the Reclaimator, a high pressure extmder, fiber-free mbber is heated to 175—205°C with oils and other ingredients. High pressure and shear between the mbber mixture and the extmder barrel walls effectively devulcanize the mixture in one to three minutes. In the Lancaster-Banbury method, high temperature, pressure, and shear are appHed to the mbber in a batch process that is otherwise similar to the Reclaimator process. In another high pressure process, scrap mbber is devulcanized at 5.5—6.9 MPa (54—68 atm) for ca five minutes. The product is milled, baled, or pelletized as in other processes. 

The degree of availability of recyclable resources such as scrap and wastes is a widely varying parameter. By way of illustration, scrap can be classified as new scrap (or in-process scrap) and old scrap (or post-consumer scrap). The former, which constitutes the majority of scrap processed at present, is derived mainly from the wastes generated during metal production and fabrication, and can be reclaimed and recycled with relative ease. 

Scrap metal Scrap metal that is disposed of or recycled is a solid waste however, it is exempt from Subtitle C regulation when it is reclaimed (i.e., recycled to recover metal content). This does not apply to processed scrap metal that is excluded from hazardous waste regulation entirely. 

Scrap metal comprises worn or extra bits and pieces of metal parts, such as scrap piping and wire, or worn metal items, such as scrap automobile parts and radiators. If scrap metal is reclaimed, it is a solid waste and is subject to hazardous waste regulation. Scrap metal is also regulated as a solid waste when used in a manner constituting disposal burned for energy recovery, used to produce a fuel, or contained in fuels or accumulated speculatively. This does not apply to processed scrap metal, which is excluded from hazardous waste generation entirely. 

Processed scrap metal. Scrap metal includes, but is not limited to, pipes, containers, equipment, wire, and other metal items that are no longer of use. To facilitate recycling, scrap metal that has been processed to make it easier to handle or transport and is sent for metals recovery is excluded from the definition of solid waste. Unprocessed scrap metal is still eligible for an exemption from hazardous waste regulation when recycled. 

Table 7.4 Processing scraps and end-of-life wastes of polypropylene and ABS property retentions versns the recycling conditions...

Glass fibre reinforced polypropylene processing scraps ... 

In processing scrap paper, there is no need for delignification with sulfur chemicals, since lignin was removed in manufacture of the new paper. If the scrap paper is to be used for packaging materials or chipboard, the color... 

In an analogous way as described above, in the case of ABS polymers that are equipped with bromine containing flame retardants, pyrolysis oils with low bromine content can be obtained (133). This issue is important for processing scrap plastics from waste of elec-... 

Making products such as reefs, playground equipment, floor mats, gaskets, etc., out of scrap whole or processed scrap tires is primarily limited by the high cost of tires compared with other raw materials. However, there are also some noneconomic barriers. Reefs made of tires, for example, are not appropriate for the rough shores of the northwest. Playground equipment made of wood or other products is often preferred for aesthetic reasons. 

Excluded scrap metal includes processed scrap metal, unprocessed home scrap metal (steel mill scrap), and unprocessed prompt scrap metal (metal fabrication scrap) (40 CFR 261.1 (c)(9), (10), (11), and (12)). 

Excluded scrap metal includes processed scrap metal, unprocessed home... 

The primary sources of Al exposure for the human and their relative contributions to daily intake are shown in Table 3.1. Concurrent consumption of citrate enhances Al absorption and tissue distribution, and in people with renal function increases its elimination. Antacids and allergy immunotherapy can provide daily Al exposures of up to 5000 and 0.007-0.040 mg in adults, respectively (Yokel and McNamara 2001). Industrial Al exposure during Al ore mining and processing, scrap metal recovery, production and use of Al compounds... 

While this fingerprinting approach is growing in popularity [51], many lead ores and coal bodies have overlapping signatures, and interpretations of predominant source areas are not always unequivocal [52]. A further caveat involves emissions of atmospheric Pb from mixtures of Pb ores. For example, secondary Pb smelters today process scrap Pb from the most diverse sources. Even during... 

The variation obtained when one person measures the same quantity several times using the same instmment. A thermoplastic material, prepared from melt-processed scrap or reject parts, or from nonstandard or nonuniform virgin material. The term scrap does not necessarily connote feedstock that is less desirable or usable than the virgin material from which it may have been generated. Reprocessed plastic may or may not be reformulated by the addition of fillers, plasticizers, stabilizers, or pigments. 

Currently, about 30% of PET soft-drink bottles are being recycled. In one recycling process, scrap PET is heated with methanol in the presence of an acid catalyst. The methanol reacts with the polymer, liberating ethylene glycol and dimethyl terephthalate. These monomers are then used as feedstock for the production of new PET products. Write an equation for the reaction of PET with methanol to give ethylene glycol and dimethyl terephthalate. 

Secondary lead is primarily sourced from scrap lead-acid batteries but also processed scrap metallics such as sheet and pipe. Secondary operations are characterised by relatively small plants in comparison with primary smelters, and are sized to handle scrap availability within a local area. This is determined by the economics of scrap battery collection and transport to the secondary operation, and it follows that the largest secondary plants are located in the high vehicle density areas of the USA. 

To understand the requirements for processing scrap lead-acid batteries, as the predominant component of lead scrap, it is useful to review the operation of a battery and its construction. The lead-acid battery uses a positive electrode or plate composed of Pb02 as (he active material, and a negative electrode or plate, composed of sponge lead as the active material. The electrolyte is dilute sulfuric acid and upon discharge both active materials are converted into lead sulfate according to the reactions shown in Equations 10.1 and 10.2. This explanation of the action of the battery is referred to as the double sulfate theory . It may be a simplistic view, but broadly explains the essential principles of the operation of the battery. 

The easiest to recycle is the in-house generated, processing scrap. At present, virtually all these materials are reused by blending (up to 40 wt%) with virgin resins. 

Low cost metal hydride materials. MH development has included improved efficiency melt/ cast processes, scrap recycle, elimination of costly sintering, versatile use of inexpensive substrate materials and significantly reduced battery formation. 

Scrap defines process scrap produced during product extrusion plus any additional... 

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