Abstract
Investigations on thermochemical transformation of asbestos fibers followed by computer aided image analysis are presented.
Asbestos Containing Wastes (ACW), notably asbestos-cement, were characterized before and after microwave heating with
additives aimed at reacting with and transforming asbestos fibers. Microprobe analysis helped determine the chemical
compositions. X ray diffraction (XRD) was used to confirm decomposition of asbestos fibers during microwave heating. Electron
paramagnetic resonance (EPR) spectroscopy was used to determine the environments surrounding the iron ions present in
asbestos fibers. Analytical results show the presence of magnesium silicates in ACW samples, which is typical for asbestos fiber
composition (chrysotile). Electronic microscopy observations show a difference in morphology between raw and treated
materials. Characteristic XRD reflections of asbestos fibers disappeared in the treated samples demonstrating the transformation
of asbestos fibers into other types of solids. Computer-Assisted-Image analysis allowed confirming automatically the absence of
fibers following heating according to the isoperimetric index of observed particles. EPR spectroscopy confirmed the
transformation of anisotropic fibers into more isotropic symmetry following melting. Thermochemical treatment was effective in
transforming asbestos fibers in ACW into non-asbestos products. The advantage of microwave heating lies in the possibility to
transport the lightweight oven to the ACW dismantling site thus avoiding transportation hazards. Computer aided Image analysis
would allow screening more images automatically to ascertain the absence of risks related to remaining fibers in numerous
treated ACW samples.