Reuse of foundry sands for core and glass production

The reuse of reclaimed green molding sands is considered in this work both for the cold-box cores production in a cast iron foundry and the production of colorless glass. The regeneration process was performed in a wet mechanical treatment plant, belonging to the Gruppo Minerali S.p.A. (Novara, Northern Italy), on 500 t of the spent green molding sands coming out from the Teksid S.p.A. cast iron foundry of Crescentino (Vercelli, Northern Italy). The recovered foundry sands were characterized by means of physical, chemical and mineralogical analyses, to compare the gathered values with the required parameters for cores production: the cold-box process was simulated on laboratory scale. Several melting tests, using different raw material mixtures, were performed to obtain colorless glass. The recycling of the reclaimed foundry sands allows the achievement of several goals: the reduction of the landfilled industrial wastes and the raw materials saving, the production of good quality products and the economic advantage. In fact in Italy the silica sand employed in foundry operations and in the glass industry has a cost about equal to 0.05 €/kg, the landfilling cost of the spent foundry sands is of about 0.10 €/kg, and the total cost of the here considered wet mechanical regeneration treatment is of about 0.03-0.04 €/kg. Thus hypothesizing that the molding sand producer (Teksid S.p.A.) would adopt the regeneration process, the potential saving could be about equal to 0.11-0.12 €/kg of reclaimed foundry sand.