Structural and microstructural aspects of asbestos-cement waste vitrification.

The main goal of the work was to evaluate the vitrification process of asbestos-cement waste (ACW). A mixture of 50 wt% ACW and 50 wt% glass cullet was melted in an electric furnace at 1400 °C for 90 min and then cast into a steel mold. The vitrified product was subjected to annealing. Optical microscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were used to evaluate the effects of the vitrification. The chemical constitution of the material before and after the vitrification process was also analyzed. It was found that the vitrified product has an amorphous structure in which the components of asbestos-cement waste are incorporated. MIR spectroscopy showed that the absorption bands of chrysotile completely disappeared after the vitrification process. The results of the spectroscopic studies were confirmed by X-ray studies - no diffraction reflections from the chrysotile crystallographic planes were observed. As a result of the treatment, the fibrous asbestos construction, the main cause of its pathogenic properties, completely disappeared. The vitrified material was characterized by higher resistance to ion leaching in an aquatic environment than ACW and a smaller volume of nearly 72% in relation to the apparent volume of the substrates. The research has confirmed the high effectiveness of vitrification in neutralizing hazardous waste containing asbestos and the FT-IR spectroscopy was found to be useful to identify asbestos varieties and visualizing changes caused by the vitrification process. The work also presents the current situation regarding the utilization of asbestos-containing products.