Foundry processes: the recovery of green moulding sands for core operations

Three different treatment processes for the reclamation of bentonite bonded moulding sands, made up of silica sand, coal dust, and clay, are considered in this work. The studied processes are the following: two kinds of wet mechanical regeneration, performed by the Safond and Sasil plants situated in Northern Italy, and a dry mechanical regeneration, performed by Gemco Engineering in the Netherlands. The performances of each treatment process were evaluated, considering the inflows and outflows. Each sample was physically and chemically characterized by means of particle-size analysis and the determination of thinness index (AFS), acid request, coal dust, oolitic, and some metals contents. The results of the inflow and outflow characterization were compared for each process to evaluate the efficiency of the considered regeneration plant. From an economic point of view, dry mechanical regeneration has proved to be the best solution but wet regeneration allows a better quality product to be obtained