All appliances and modules consisting mainly of electronic components fall under the category of electronic waste appliances. This group comprises the following categories: entertainment electronics, office, information, and communication appliances, and electronic components of appliances.
Owing to the rapid pace of technical developments, the composition of appliances is subject to continual change. Particular attention must be paid to
1. Batteries and accumulators
2. Mercury switches/mercury relays
3. Condensers containing PCBs
4. Photoconductive drums of copying machines coated with selenium arsenate or cadmium sulfide
5. Cathode ray tubes (CRTs)
6. Printed circuit boards
7. Wood treated with paints, varnishes, and preservatives
8. Plastics containing halogenated flame retardants.
Furthermore, appliances also contain valuable constituents such as gold (from connectors), nickel, copper, iron, aluminum, and permanent magnets, which are worth recovering.
The objectives for disposal of electronic waste appliances are (a) stripping of hazardous substances; (b) reduction of pollutant and metal contents in the plastic fraction, thus permitting recycling or incineration in waste incineration plants or cement works; (c) recovery of nonferrous metals; and (d) attainment of commercially recyclable scrap quality.
The requirements for proper disposal of electronic waste appliances are as follows: (a) appliances may be broken up (shredded) only if the components containing particularly hazardous substances have previously been removed and (b) since in disposing of electronic appliances the main emphasis is on the recovery of nonferrous metals, nonstripped appliances must not be shredded together with scrap cars. As a rule, electronic appliances are dismantled manually to achieve effective separation of the components containing hazardous substances.
Typical examples of the disposal of electronic waste appliances include the following steps:
1. Stripping of hazardous components: In an initial step, the components containing particularly hazardous substances are for the most part removed manually.
2. Shredding of appliances and separation of fractions: The stripped appliances are, as a rule, 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, turborotor, sink-float, eddy current, or magnetic separation. The separated fractions are handed on to workable lots for further processing or recycling, or to resellers.
4. Handling and processing of stripped components containing particularly hazardous substances: Batteries and accumulators are classified as hazardous wastes even if they are recycled. Mercury is classified as a hazardous waste and can be recovered in special plants. Condensers containing PCBs must be incinerated in a hazardous waste incineration plant.
5. Separation of ferrous and nonferrous metals, copper, and aluminum for separate recovery: The scrap material and scrap metal dealers sort these metals (in part very finely) and send them to steelworks at home and abroad.
6. Handling and processing of CRTs: CRTs are handled for special processing.
7. Processing of printed circuit boards: Printed circuit boards are subjected to special treatment in order to recover their entire metal content.
8. Recycling of plastic-sheathed cables: Electrical cables are sent to cable recycling plants that separate the plastic and copper components.
9. Disposal of residual fraction: Depending on their quality and on the specific requirements applicable, residual fractions are disposed of in MSW incinerators, hazardous waste incinerators, cement works, or they are recycled.
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