Special sand-spherical kaolin sand and preparation method thereof

Abstract

The invention provides special sand-spherical kaolin sand and a preparation method thereof. According to the special sand-spherical kaolin sand and the preparation method thereof, raw kaolin is adopted for production through a high-temperature melting method so as to obtain the spherical kaolin sand, and the raw kaolin comprises Al2O3, SiO2, Fe2O3 and TiO2, wherein the content of the Al2O3 is greater than or equal to 45%, the content of the SiO2 is greater than or equal to 45%, the content of the Fe2O3 is less than or equal to 0.5%, and the content of the TiO2 is less than or equal to 0.5%. The special sand-spherical kaolin sand and the preparation method thereof have the beneficial effects that the raw kaolin which comprises the Al2O3 with the content being greater than or equal to 45% and crystal phases with the content being greater than or equal to 90% is adopted to be subjected to high-temperature fusion to form spheres, the crystal phases are changed to form mullite phases whichis greater than 90% or above, the spherical fused raw kaolin sand in the crystalline state has an extremely low expansion rate, and the size precision of a casting can be guaranteed after a shell is manufactured.

Description

technical field [0001] The invention belongs to the technical field of casting, and in particular relates to a special sand-spherical kaolin sand and a preparation method thereof. Background technique [0002] At present, the most widely used molding sand in casting is angular silica sand, which is widely used because of its low price and simple source, but because of its irregular angular shape, it leads to poor fluidity and low filling rate, resulting in the sand mold formed by silica sand. The surface is rough, resulting in poor surface finish of the casting, which increases the difficulty of subsequent processes. At the same time, the main component of silica sand is quartz, and the crystal phase changes under the influence of high temperature during pouring to form cristobalite. The volume changes greatly, and castings with high dimensional accuracy cannot be obtained, which also increases the difficulty of subsequent processes. Therefore, a lot of non-angular sand has...

AI Technical Summary

Problems solved by technology

[0006] In the above-mentioned disclosed patents, there are spherical molding sand and high-siliceous spherical molding sand obtained by mixing raw materials, granulating into balls and sintering, but the sphericity is not high, the surface of the sand grains is rough, and many binders are used, resulting in high cost. It does not improve the filling rate, that is, the surface finish of the casting; another patented spherical molding sand reduces the surface roughness of the sand grains, uses less binder, has high sphericity, and has good fluidity, which improves the filling rate of the sand mold and the surface finish of the casting. Because the main components are alumina and silicon oxide, the specific gravity is large, and the sand mold is heavy, which makes the labor intensity of workers high, and there is a problem of high cost at the same time