Extraction of heavy metal (Ba, Sr) and high silica glass powder synthesis from waste CRT panel glasses by phase separation

Abstract

In this study, a novel process for the extraction of heavy metal Ba and Sr from waste CRT panel glass and synchronous preparation of high silica glass powder was developed by glass phase separation. CRT panel glass was first remelted with B2O3 under air atmosphere to produce alkali borosilicate glass. During the phase separation process, the glass separated into two interconnected phases which were B2O3-rich phase and SiO2-rich phase. Most of BaO, SrO and other metal oxides including Na2O, K2O, Al2O3 and CaO were mainly concentrated in the B2O3-rich phase. The interconnected B2O3-rich phase can be completely leached out by 5mol/L HNO3 at 90 ℃. The remaining SiO2-rich phase was porous glasses consisting almost entirely of silica. The maximum Ba and Sr removal rates were 98.84% and 99.38% and high silica glass powder (SiO2 purity > 90 wt%) was obtained by setting the temperature, B2O3 added amount and holding time at 1000–1100 ℃, 20–30% and 30 min, respectively. Thus this study developed an potential economical process for detoxification and reclamation of waste heavy metal glasses.