Lead recovery from waste CRT funnel glass by high-temperature melting process

Highlights: • Lead silicate in the waste CRT glass was reacted into lead sulfide by sodium sulfide. • CRT funnel glass was sintered into glass slag in the high-temperature melting process. • Lead sulfide was reduced into metallic lead. • The generated metallic lead was collected at the bottom of the crucible. - Abstract: In this research, a novel and effective process for waste CRT funnel glass treatment was developed. The key to this process is removal of lead from the CRT funnel glass by high-temperature melting process. Sodium carbonate powder was used as a fusion agent, sodium sulfide serves as a catalytic agent and carbon powder acts as reducing agent. Experimental results showed that lead recovery rate increased with an increase in the amount of added sodium carbonate, sodium sulfide, carbonate, temperature and holding time initially, and then reached a stable value. The maximum lead recovery rate was approximately 94%, when the optimum adding amount of sodium carbonate, sodium sulfide, carbonate, temperature and holding time were 25%, 8%, 3.6%, 1200 °C and 120 min, respectively. In the high-temperature melting process, lead silicate in the funnel glass was firstly reduced, and then removed. The glass slag can be made into sodium and potassium silicate by hydrolysis process. This study proposed a practical and economical process for recovery of lead and utilization of waste glass slag.