Shred
Mechanical processing is the next step in e-waste treatment, normally an industrial large scale operation to obtain concentrates of recyclable materials in a dedicated fraction and also to further separate hazardous materials. Typical components of a mechanical processing plant are crushing units, shredders, magnetic- and eddy-current- and air-separators. The gas emissions are filtered and effluents are treated to minimise environmental impact. Indoor exposure is monitored and assessed and kept within Swiss Maximum Allowable Concentration (MAC)-levels to assure workers safety.
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PC: Before shredding, it is efficient to remove umixed material as much as possible. After having stripped all components containing hazardous substances, the remaining parts are ground in a fine shredder (e.g. rotary cutter). The material resulting from this can be further processed by several methods. Possible processes are: air classification, riddle screening, cyclone, turbo-rotor, sink-float, eddy current or magnetic separation. The separated fractions are handed on in workable lots for further processing or recycling or to resellers. The main fractions are metal containing fractions, e.g. steel, stainless steel, copper, connectors and contacts containing gold, aluminium and residual fractions, e.g. plastics, wood.
For Cathode ray tubes (CRT's) and printed circuit borads special processes exist. |
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Refrigerator: Shredding and fractionation of the main unit of a refrigerator takes place under partial vacuum in an enclosed disposal facility. Polyurethane foamed with ozone depleting CFCs is pressed out as completely as possible. The vitiated air from the shredder and the press is cleaned through activated carbon and passed through a condensation cooling system. In this special unit, the CFCs are recovered with practically no losses. After the appliances are shredded metals, foam and foreign matter are separated. |
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Light-Bulb: Glass and metal parts are separated. Luminescent substances from new-generation lamps are recovered separately to facilitate direct re-use of phosphor powder. Luminescent powder of older fluorescent lamp models needs to be disposed of in a special storage facility. Clean glass tubes are shredded and remaining metal parts are sorted out with a metal stripper. |
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Battery: In Switzerland, household batteries are recycled in the special high-temperature facility Batrec. Ni/Cd batteries and lead-acid accumulators are segregated prior to treatment and handed over to specialist recycling companies. |