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The arc-plasma vitrification of a hospital wastes containing metals and inorganic oxides yields to a leachresistant glassy or vitreous slag, which can be environmentally safe for landfill disposal or could be transformed in glass-ceramic tiles with physical and mechanical properties similar to those showed by marketable products for building applications. Standard methods have been used for testing the leachability of elements from this new type of tiles. The water resistance was evaluated by the DIN 38414 S4 standard and the chemical durability of glass and glass-ceramics by the weight losses per surface unit, employing NaOH and HCl (5%) aqueous solutions, at boiling temperature. Results show that although glass-ceramic tiles are most water leachable than original plasma vitreous glass, the concentration of toxic minor elements in their leaching solutions are lower than those allowed by the Normative.

The feasibility to crystallise a glass prepared by thermal plasma vitrification of hospital wastes to produce a glass-ceramic suitable to be used as a construction material was investigated by using differential thermal analysis (DTA) and X-ray diffraction (XRD). Two crystallisation exotherms in DTA were attributed to the formation of wollastonite and a crystalline phase belonging to the melilite group (gehlenite or akermanite). DTA tests have shown that the glass is not suitable for bulk crystallisation and must be converted into a glass-ceramic by using the sintering process route through a single crystallisation step at 1000 •C for 10 min.