Recycling of fine fraction of spent foundry sands into fireclay bricks

The most large-scale foundry waste is burnt molding earth, which is formed at the stage of knocking out castings from foundry molds. The properties of burnt molding earth (humidity, loss on ignition, elemental, phase, and grain composition) were studied and the possibility of its regeneration was confirmed. It is shown that during mechanical regeneration, about 24 wt.% of the considered waste turns into a fine pulverized fraction, which cannot be returned to the technological process and is sent to a landfill. On the basis of experimental studies, it has been established that this fraction of burnt molding earth can be used in the production of ceramic bricks as a lean additive. The obtained samples of ceramic bricks containing 20 wt.% finely dispersed fraction of molding burnt earth at a firing temperature of 1000 °C for 60 min are characterized by the following properties: average density 2020 kg/m3, water absorption 10.8%, compressive strength 39.8 MPa, and ultimate strength in bending 12.67 MPa.