The main properties of chromite sand
(1) Chromite sand has a good anti-alkaline slag effect, and does not react with iron oxide, etc.; therefore, in practical applications, chrome ore can avoid thermochemical sticky sand;
(2) During the molten metal casting process, the chromite sand itself undergoes solid phase sintering, which prevents the penetration of the molten metal, thereby preventing mechanical sticking of sand;
(3) The thermal conductivity of chromium ore sand is several times larger than that of silica sand, which can improve the cooling rate of castings. Therefore, chromite sand can play the role of external cold iron in practical applications;
(4) The harmful impurity in chromite sand is carbonate (CaCO3·MgCO3), which decomposes CO2 when it is in contact with high-temperature metal, which is easy to cause pores in castings; usually, the chromite sand containing carbonate is heated at 900 ° C -950°C high temperature roasting to decompose the carbonate.
(5) Effect of particle size of chromite sand on its refractoriness The particle size of chromium ore can significantly affect its refractoriness. In the past, it was believed that too coarse particle size would reduce the surface finish of the casting, but the surface of the sand mold and sand core made of chromite sand is usually sprayed with a certain thickness of paint, so that the surface finish of the casting is hardly affected.
Generally, the suitable particle size of the sand mold used in the modeling of large steel castings is 40/70 mesh, and the particle size of the sand used for medium and small parts is 50/100 mesh. There are also some special cases such as: some small water pump industries, considering economic factors, replace zircon sand with chromite sand, the chromite sand purchased by these factories is required to be very fine, requiring 70/140 mesh, or even 100/200 mesh