Lead recovery and glass microspheres synthesis from waste CRT funnel glasses through carbon thermal reduction enhanced acid leaching process

• Published in: Journal of hazardous materials 2016-03, Vol.305, p.51-58
• Main Authors: Mingfei, Xing, Yaping, Wang, Jun, Li, Hua, Xu
• Format: Article
• Language: English
• Subjects: Carbon thermal reduction; CRT funnel glass; Glass microspheres; Hazardous waste; Lead recovery
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2015.11.032

[Display omitted] •CRT funnel glass was sintered into glass microspheres in carbon reduction process.•Meanwhile, PbO in funnel glass can be quickly reduced into metallic Pb.•The generated metallic Pb was mainly located on the surface of glass microspheres.•Pb was readily removed by HNO3 and harmless glass microspheres were obtained. In this study, a novel process for detoxification and reutilization of waste cathode ray tube (CRT) funnel glass was developed by carbon thermal reduction enhanced acid leaching process. The key to this process is removal of lead from the CRT funnel glass and synchronous preparation of glass microspheres. Carbon powder was used as an isolation agent and a reducing agent. Under the isolation of the carbon powder, the funnel glass powder was sintered into glass microspheres. In thermal reduction, PbO in the funnel glass was first reduced to elemental Pb by carbon monoxide and then located on the surface of glass microspheres which can be removed easily by acid leaching. Experimental results showed that temperature, carbon adding amount and holding time were the major parameters that controlled lead removal rate. The maximum lead removal rate was 94.80% and glass microspheres that measured 0.73–14.74μm were obtained successfully by setting the temperature, carbon adding amount and holding time at 1200°C, 10% and 30min, respectively. The prepared glass microspheres may be used as fillers in polymer materials and abrasive materials, among others. Accordingly, this study proposed a practical and economical process for detoxification and recycling of waste lead-containing glass.