Recycling of slag and fly-ash from MSW incineration for zero-ing landfilling strategies

In regions where the European Union Directives are complied with, the trend in Municipal Solid Waste management is often based on a significant increase of the efficiency of selective collection (up to 65%) and on the thermal treatment of the residual waste (in some cases after transformation into Refuse Derived Fuel). When a conventional strategy (combustion) is adopted for thermal treatment, a weakness concerns the need of landfilling for disposing of slag and fly-ash. Concerning slag, the selective collection of inert fractions allows decreasing the amount of mass to be landfilled after burning, but the landfilling volumes are not zero. Concerning fly-ash, the long distance transport towards exhausted mines authorized for final storage of hazardous waste is not considered anywhere an optimized solution, even if still adopted in many European countries. For these reasons, in Italy, some recent proposals of Waste-to-Energy plants for Residual Municipal Solid Waste treatment are opened to innovative solutions for the management of slag and fly-ash. One of these is presented in this paper and regards the verification of fly-ash. In the first part of this paper the results of a research made at the University of Trento is presented. In the second part of this paper a real scale case study concerning slag recycling in real scale is presented.