Energy-efficient modification of reduction-melting for lead recovery from cathode ray tube funnel glass

摘要

Lead can be recovered from funnel glass of waste cathode ray tubes via reduction melting. While low-temperature melting is necessary for reduced energy consumption, previously proposed methods required high melting temperatures (1400 ℃) for the reduction melting. In this study, the reduction melting of the funnel glass was performed at 900-1000 ℃ using a lab-scale reactor with varying concentrations of Na_2CO_3 at different melting temperatures and melting times. The optimum Na_2CO_3 dosage and melting temperature for efficient lead recovery was 0.5 g per 1 g of the funnel glass and 1000 ℃ respectively. By the reduction melting with the mentioned conditions, 92% of the lead in the funnel glass was recovered in 60 min. However, further lead recovery was difficult because the rate of the lead recovery decreased as with the recovery of increasing quantity of the lead from the glass. Thus, the lead remaining in the glass after the reduction melting was extracted with 1 M HCl, and the lead recovery improved to 98%.