Fast‐Sintered Gehlenite Glass–Ceramics from Plasma‐Vitrified Municipal Solid Waste Incinerator Fly Ashes

Plasma heating is a highly efficient industrial treatment for municipal solid waste incinerator fly ashes, converted into leach‐resistant glass. The viscous flow sintering of glass powders appears a very promising way for the subsequent conversion of the vitrified waste, not refined and available as glass flakes, into valuable glass–ceramics. Because of the particular glass composition, the densification of glass–ceramics was much hindered by the strong tendency of glass toward surface crystallization. The crystallization of glass was successfully coupled to a low porosity, thus yielding strong gehlenite‐based glass–ceramics (with a bending strength exceeding 100 MPa), by adopting a fast sintering treatment (direct insertion of glass compacts at 1050°C, with an holding time of 1 h).