one of the most serious environmental problems of the developed countries is related with the difficulty in finding alternative treatments for the produced industrial wastes. slag produced by biomass boilers is an example of these industrial wastes and is usually used for road wadding, land corrective mixtures, sludge inertization or landfilling. however, these undesirable wastes can offer interesting valorisation capabilities. the main purpose of this work was to try an alternative way of recycling industrial wastes from a biomass boiler. the slag was produced in a portuguese plant ？celulose do caima？, located in constancia-sul, and producing about 70 tons of slag per month. vitrification of the slag was the tested procedure as suggested by its chemical and mineralogical composition. physical, chemical, mineralogical and thermal characterisation of the slag indicated a high proportion of sio2 (>81%) and a particle size distribution in the range 0,06-53 mm. in order to produce a melt of suitable viscosity for casting and aiming to favour vitrification, na2o was used as fluxing agent, which was provided by soda solvay. the mixture was heated at 1450 oc and gave rise to a castable melt and a homogeneous green coloured glass on cooling. characterisation of the obtained glass by differential thermal analysis and dilatometry showed thermal properties similar to the ones of other glasses obtained from waste vitrification. the results also indicated that these glasses are capable of being further heat treated to obtain structural materials to be used in building applications, such as floor and wall cladding panels.