Combined Fe2O3 and CaCO3 Additives To Enhance the Immobilization of Pb in Cathode Ray Tube Funnel Glass

摘要

Cathode ray tube (CRT) funnel glass has posed an increasing threat to the environment due to its rapid replacement by new technology in recent years. In this study, a well-control thermal scheme was applied for synthesizing a specific crystalline phase, PbFe12O19, for Pb immobilization when reusing CRT funnel glass as raw materials for the ceramics industry. The Fourier transform infrared spectroscopy results show that introduction of CaCO3 facilitated the breakage of strongly connected bonds between O-Si-O and Pb-O, which were firmly linked in the glass network. The Xray diffraction results demonstrate that 30 wt % CaCO3 loading effectively facilitated the transformation of Pb in CRT funnel glass to the stable-phase PbFe12O19. A higher sintering temperature increased Pb transformation efficiency while a longer dwelling time only showed a slight increase in PbFe12O19 formation. The prolonged toxic characteristic leaching procedure results show a substantial improvement in the acid resistance (approximately 2 mg/L) of the thermally treated product with 30 wt % CaCO3 loading and sintering under 1000 degrees C for 5 h compared to the original CRT funnel glass (500 mg/L). The results of this study demonstrate that incorporation of CaCO3 and Fe2O3 into CRT funnel glass can effectively promote Pb immobilization and provide a new strategy for stabilizing waste CRT funnel glass.