Monday, May 11, 2009

Recycling cathode Ray tubes


Due to the environmental risk and processing difficulty CRTs pose the greatest problems to
the electronics recycling industry. Mercury and hexavalent chromium are found in CRTs those can be considered as more toxic substances. The densities of these toxic material differ from places as example panel glass of a CRT only contains 4% lead, but the funnel and neck glasses contain up to 28% and 30%, respectively.

CRTs are recycled by initially either shredding the entire unit (with or without casings), or separating the glass components (panel, funnel, neck and frit). Shredding results in a mix
of glass and lead that is subsequently separated by electro-magnetic or density methods. The resulting glass, which contains varying levels of lead, is often smelted in a furnace to convert
the lead ore in a reaction with carbon based fuel to elemental lead. Separating the glass components first requires manual separation of the CRT from its housing and other exterior parts. Then, separating the glass before shredding allows the individual glass streams to be sent to either glass-to-glass (GtG) processors or smelters.

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