Recognition of Ceramic Glass Contaminants in Recycling Glass by FT-IR Spectroscopy

The presence of ceramic glass contaminants in the glass recycling plant reduces production quality and increases production costs. Ceramic glass detection is not an easy task as such material looks like normal glass and is detectable only by specialized personnel. The presence of glass-like contaminants inside waste glass products, usually resulting from both industrial and differentiated urban waste collection, strongly increased in these last years, due to the introduction on the market of a large amount of ceramic glass manufactured goods. These materials, presenting melting points higher than that of glass, are responsible for the presence of defects in the recycled glass products, not permitting their re-use and/or, in some cases, for the damage of the furnaces. In this paper an innovative approach for ceramic glass recognition, based on FT-IR spectroscopy, is proposed and investigated. The work was specifically addressed on the spectral characterization of glass and ceramic glass fragments presenting different colour, thickness, shape and manufacturing in order to define suitable inspection strategies to perform inside recycling plants the required separation between useful (glass) and polluting (ceramic glass) materials. The analyses, carried out in the mid-infrared spectral field (1280-4480 nm), show as ceramic-glass and glass fragments can be recognized according to their different spectral signature.