Combination Technology of Mechanical Treatments and Vacuum-Carbon-Reduction for Recovering Hazardous Glass Diodes

Abstract

Volumes of waste glass diodes are generated with the increasing amount of obsolete electrical and electronic devices. These diodes containing 60 wt % PbO should be considered as hazardous waste for disposal. However, relevant research about their disposal is deficient so that glass diodes have not been effectively treated yet. Thus, a combined technology, comprising crushing, screening, magnetic separation, and vacuum-carbon-reduction, was proposed for the harmless treatment and resource recovery of waste glass diodes in this study. The energy analysis assisted the optimization of the crushing process. After optimization, metal materials with d > 0.6 mm were separated from the glass powder with d < 0.2 mm by screening and magnetic separation, which can reach a separation rate of 96 wt %. As for the high Pb-bearing glass, a vacuum-carbon-reduction process was applied for Pb removal. Under the optimal conditions of ball-milling pretreatment, 9 wt % of graphite added, reaction temperature of 1000 °C, and retention time of 3 h, the maximum Pb removal rate could reach 98.87%. Amorphous glass powder transformed into crystalline SiO2, and Pb reduced from PbO could be collected centrally. This paper provides scientific information and green combination technology for disposing of waste glass diodes.