Dust emission during release of vacuum from cathode-ray tubes

Status:

completed 10/2001

Aims:

Recycling of electronic scrap includes sorting of the components of visual display units into individual recoverable materials and pollutants. Before cathode-ray tubes are dismantled, the vacuum must be broken. Initiated by the institution for statutory accident insurance and prevention in the precision engineering and electrical industry this project considered which protective measures, if any, were required.

Activities/Methods:

The vacuum of cathode-ray tubes was to be broken under reproducible conditions on a test bench in accordance with DIN 33896-1 for the purpose of measurement of the dust emission rate from machines for use on work tables, Part 1: basic procedure, in order to permit estimation of the potential hazard according to the emissions measured.

Results:

72 cathode-ray tubes were broken in three experiments using three different methods to release the vacuum. In all experiments the emission of dust was observed. With one exception, however, in which small quantities of lead were detected, neither lead nor cadmium were detected in the total dust. The observed lead emission of approximately 0.05 mg per cathode-ray tube is sufficiently low that a violation of the German atmospheric limit value of 0.1 mg/m³ need not generally be anticipated. The lead emission must however be considered critically with regard to dermal exposure and oral intake. The working conditions must be organized such that skin contact with and oral intake of the dust are excluded. The results of the project have been exploited for the formulation of protective measures in the BG/BIA recommendations governing the manual dismantling of monitors and other items of electrical equipment. A particular recommendation is the use of a cleaning booth with exhaust system.

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