The roasted sand
the roasted sand is a kind of high-quality base sand for producing pre-coated sand, obtained by high temperature treatment of the baked sand. The roasted sand features of clean surface, low expansion rate, low mud content, and low loss on ignition. In the resin bonded sand process, it can greatly improve the bonding efficiency, reduce the amount of resin added, and reduce the amount of gas generated from the sand core. At the same time, due to the phase change of silica sand after high temperature roasting, the casting defects resulted by sand expansion and gassing defects could be greatly reduced.