Industrial treatment processes for recycling of green foundry sands

Three treatment processes for the reclamation of green moulding sands coming out from a cast iron foundry located in Northern Italy are considered in this study. A wet mechanical treatment, a dry mechanical treatment and a dry mechanical plus heat treatment are compared to evaluate the efficiency of each process and to point out the best regeneration solution for the recycling of reclaimed sand in foundry operations. The inflow and the outflow samples of each process were characterised by means of particle size analysis and the determination of silica, loss on ignition, acid request, oolitic and some metals contents. A final evaluation of the three processes was performed taking into account the obtained quality of recovered silica sand and the economical aspects; the wet mechanical and the dry mechanical plus thermal treatments are most effective for the recovery of green moulding sands coming out from the considered foundry plant for cold box core production.