Reclamation of foundry sands.

摘要

A used foundry sand, especially one which has been bonded using sodium silicate binder, is reclaimed by agitating the sand with water in a plenum chamber having a suspended floor comprising a porous membrane, stopping the agitation and allowing the solids to settle on the floor. The water passes through and the sand settles on the floor, and the finer particles may then be removed e.g. by air elutriation. Preferably the water mixed with the sand has a pH below 10 and contains a flocculant and the water recovered from the vessel has suspended solids content below 500 mg/litre.