USE OF GRANULATED BLAST-FURNACE SLAG FOR STABILIZATION OF STEELMAKING FLUE DUST

This report examines how the toxicity of electric arc steelmaking flue dust can be reduced by means of a stabilisation process using granulated blast furnace slag. This process makes it possible to immobilise the metal contents which make the flue dust a hazardous product. Stabilisation is carried out in two consecutive pelletisation stages. The first involves pelletising the steelmaking flue dust and the second involves coating these pellets with a mix composed of slag based hydraulic binders. The report then considers the effects of different slag binding mixes containing Portland cement, gypsum, and lime on stabilising steelmaking flue dust and reducing its level of toxicity. The results of the experiments carried out show that the binding mixtures used reduce the mobility of those metals which lead to flue dust being classified as a hazardous product, giving EC50 values of greater than 0.3% and reducing toxicity by between 96 and 99%. The mix that offers the greatest crushing strength was found to be a conglomerate of 85 wt-% slag and 15 wt-% cement. (C) 1993 The Institute of Materials.