Advantages | Plastic coated cable scrap | Environmentally sound process | Cable chopping process description | Cable stripping process description | Manufacturers of equipment | Equipment prices | Equipment suppliers

Cable granulation	Cable stripping
Supports processing of mixed cable types and cut cable scrap.	Supports lowest-cost processing of longer cable lengths.
Environmentally sound process Typical installations can process 400 kg up to 4000 kg/hour 99,5% pure copper or aluminium granulate 99,5% pure plastic granulate Can be adapted to future cable scrap types Can be easily adapted to process small tonnages of different scrap cable type	Environmentally sound process Fast, simple and affordable Low cost, easy to use,safe process No loss of materials Can be easily adjusted to process different scrap cable type

In 1997, world-wide over 1,800,000 tonnes of insulated wire and cable scrap was generated. This scrap contains on average about 60% metal or 1,080,000 tonnes and 40% plastics or 720,000 tonnes. The conducting metal in this scrap is primarily copper. Though, power transmission cables have aluminium as the conducting metal. Utilities use insulated aluminium power cable as outside distribution cable and primarily insulated copper wire for inside distribution. Building, communication, electronics and automotive markets normally use copper as the conducting metal.

This cable scrap is valuable, mainly because it contains copper and aluminium metal, although the plastic also has value and can be recycled or reused. An industry has specifically developed to recover these metals.

Cable scrap arises in all countries, OECD and non-OECD. Most scrap cable is recycled domestically in OECD countries, only an estimated 15% of cable scrap is exported, not so much because of lack of domestic capability but because of market forces. The USA, W. Europe, Japan, Canada, Singapore and Australia ship cable scrap to the developing countries; in particular, China, Vietnam, S. Korea, Mexico, Indonesia, Malaysia, Thailand, Taiwan, India, Pakistan, Argentina, Brazil and Chile. Export of metal-containing cable scrap to developing countries amounts to an estimated 80,000 tonnes from the USA, some 72,000 tonnes from Japan and an estimated 20,000 tonnes from Europe annually. About 30% of these scrap cables are re-used rather than recycled in non-OECD countries. Cable scrap is shipped according to widely accepted trade specifications and classifications.

The dominant plastic materials used in insulated cables are PVC and polyethylene. In the USA, these plastics are used almost equally. In Western Europe and Japan the use of PVC is greater than the use of polyethylene. Both plastics are thermo-plastics and can therefore be remelted during the recycling process.

Cable scrap is generated by cable manufacturers and end-users such as utility and telephone companies, manufacturers of electronic and electrical equipment, and electrical contractors. This is pre-consumer scrap (or 'new scrap').

On the other hand, cable scrap recovered while replacing old cable lines with new ones or from end-of life electronic equipment is called post-consumer scrap (or 'old scrap').

Utilities, which are a major source of scrap, generate pre-consumer scrap in the installations of new lines -- reel ends, etc. -- and post-consumer scrap from dismantling old lines. This scrap arises in all countries whether OECD and non-OECD, therefore each country will require some form of domestic treatment for this coated cable scrap. As raw materials have become more expensive and companies more environmentally conscious over the past decade, many continuous improvement programmes have started bringing a reduction in production wastes.

Pre-consumer cable scrap is preferred by the cable scrap processor, because it is a "known" waste material (some countries do not consider these materials as "wastes"). For example, a power cable manufacturer generates a waste stream that usually contains only aluminium metal and polyethylene, while a manufacturer of communication cable often generates a waste stream that contains only copper metal and PVC. Post-consumer scrap is the same material as pre-consumer but the wastes are more dispersed and need dismantlement. These wastes require transport and co-ordination to be environmentally and cost effectively recycled.

The predominant way of recovering the metal from cable scrap in the developed countries is automated cable chopping. The technology is available all over the world. Most cable chopping plants process only copper cable scrap, a few only process aluminium cable scrap, and some operate both a line for aluminium and another for copper cable scrap.

Systems vary in size from 225-680 kg/hr. to 4,770-5,455 kg/hr. and cost, based on 1997 prices, vary from $150,000 for small machinery to $1,800,000 for larger machines. Cable processors in Europe tend to install small to medium-sized lines handling 0.5 tonnes to 3 tonnes/hr and which tend to produce an overall finer chop grind than U.S. cable processors. U.S. cable choppers typically use larger lines with capacities reaching at least 5 tonnes/hr. Many of these systems are suitable for developing countries.

In North America, about 100 plants operate wire chopping lines with a production of 540,000 – 640,000 tonnes/yr. Cable chopping lines in Japan process some 500,000 tonnes of cable scrap in approximately 100 plants, including 10 major ones. Cable chopping lines are also in Western Europe, Morocco, Tunisia, Australia, Brazil, Argentina, and Chile. China has 6-7 cable chopping plants, and Russia recently acquired one or two plants from a US manufacturer.

The environmental sound recovery of cables by wire chopping typically includes the following steps:

Pre-sorting

Pre-sorting includes the separation of long cable sections, by type of insulation, by conductor diameter, or as plated or unplated conductor, or densely baled cable, whereas pieces of ferrous and non-ferrous metal from loose cable can be fed directly to the shredder. The pre-sorting is the most important element of the environmentally sound management of cables scrap, it also allows to get maximum value for the recovered metal scrap and to make further separation of plastics easier. Long cable sections are sheared into lengths of about 1m so that they can be fed into the granulator, while densely baled cable has to be broken up into loose streams. Most importantly, pre-sorting includes sorting copper- from aluminium-containing cable. These machines process anything from 8 cm diameter cable to thin cable of about 26-gauge. Material not well-suited to such automated systems can be separated out beforehand, for example superfine "hair wire" and grease or tar-filled cables that can obstruct the system (these can be manually separated).

Cable chopping

Chopping is normal in larger plants but optional in smaller plants and is usually desirable for processing long cable sections. It is the first step in reducing the size of the cable chop. Compared to shredding, cable chopping produces little if any filter dust.

Granulation

In the primary granulator stripping of the insulator and jacketing is only partially accomplished, as the cable chops are typically about 7-8 cm in length. The secondary granulator produces maximum lengths of about 0.6 cm. Such fine chopping usually liberates most of the insulation from the cable but inevitably small amounts of metal remain embedded in the plastics.

Screening

To enhance the recovery of metal, some chopping lines also use screening to yield the desired chop size. The smaller the chop size the more efficient the removal of the metal. Some systems use vibrating screens that prepare the chops for final metal separation. Here the "fines" containing metal, plastic, fibres, and dirt drop through the bottom screen. The metal is recovered, while an aspirator sucks up the non-metallics. Dust collection using a cyclone collector occurs at many points throughout the system and filter system further cleans the air before exhausting.

Density separation

Similar-size fractions of the chops that collect on the screens are then discharged and fed to an air table that is slanted in two directions. The chips enter from the rear of the table, and the mix is fluidized by air—lighter particles are lifted higher than heavier ones. Consequently, the heavier metal particles move up the table, while the lighter particles of plastic residue or "tailings" float downslope. The fluidized bed separator produces two fractions: clean metal product and essentially metal-free tailings. Generally, "middling" fractions are reprocessed again in the system or can be re-tabled.

Though all cable processors seek the best metal recovery, some metal — both loose and embedded — eludes capture. Metal content of residue streams can vary from less than 1% to more than 15%. Some cable processors have installed dry electrostatic systems. For example, electrostatic separators can reduce the metal content of tailings from 5-15% to less than 0,1%. The use of electrostatic precipitators or separators reduces the metal content in the tailings, therefore increases the value of the recovered plastic.

For example, PVC is recycled in pellets or directly reused for insulation of electric cable, insulation tape, car mats, carpet lining, flooring and footwear, etc. (about 50,000 tonnes per year).

A less costly and as environmentally sound process for material separation is cable stripping, but it is a process with much lower throughput. Such equipment is designed to handle only single strands of cable waste at rates up to 60 m/min. or 1,100 kg/min with cable that is as thin as 1.6 mm or as thick as 150 mm. In 1997, machines that operate at 24 m/min. sell for about $5,000, whereas small tabletop machines that operate at rates of only 8 m/min. sell for as little as $1,800 in the U.S.A. and Europe. These machines are manufactured in many countries.

Many of the developing countries use these machines rather than the more expensive cable chopping machines. For example, Cyprus, India, Israel, Jordan, Latvia, Lebanon, Russian Federation, Saudi Arabia, United Arab Emirates, Vietnam, Pakistan, China and others use these machines. Cable stripping machines are also used in most developed countries, where these machines are used by utilities, cable manufacturers, cable chopping companies and metal scrap dealers.

The advantages of stripping, in contrast to chopping, is the purity of the recovered jacketing and insulation materials. It is completely free of conducting metal and, if the user is careful in segregating the cable scrap before it is processed, the tailings can consist of one type of polymer. This way, the tailings, both metal and polymer, become more easily recyclable.

Processors in the developing countries have found that the stripping process is attractive, because they can recycle the tailings, such as plasticized PVC, with relative ease. The capital and operating costs for these machines are also very affordable.

Manufacturers such as those listed have been manufacturing equipment to reprocess cable for over 25 years. Simple equipment can remove the casing and insulation off cable prior to granulation or simply to sell on as clean copper or lead. Larger, heavy duty equipment can process high tonnages of mixed cable down to end-product granulated metal which is 99% to 99.9% pure. Shredders and granulators are installed all over the world and have been in operation for many years.

A recent and typical installation by Metpro consists of two heavy duty granulators and a robust and efficient air bed separator with connecting chevron type conveyors for the separation of telecommunications cable with end products up to 99% clean. It has other applications for electronic and telecommunications scrap, heavy-duty wire armoured electrical cable up to 50mm in diameter and aluminium profiles.

Smaller plants, capable of handling 0.25 to 0.5 tonnes per hour, can be operated by one person and are ideal for smaller processors and family businesses. These systems are often modular, so that they can be easily added to to increase their capacity. They use state of the art technology, which is mechanical and completely free of any harmful effects to the environment or to the user, and very cost-effective.

All this equipment allows for the recovery of all the metals in scrap cable with almost 100% levels of purity and uses can also be found for the plastic insulation.

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