CRT funnel glass was remelted with B2O3 in reducing atmosphere.
A part of PbO was reduced into Pb and detached from the glass phase.
The rest of PbO and other metal oxides were mainly concentrated in the B2O3 phase.
PbO enriched in the interconnected B2O3 phase can be completely leached out by HNO3.
High silica glass powder(SiO2 purity >95%) was obtained after the leaching process.