Few domestic foundry manufacturers use old sand regeneration equipment, and even fewer enterprises use old sand regeneration equipment for sodium silicate sand. The reason is not that enterprises are unwilling to regenerate old sand, but that there is no ideal “old sand regeneration equipment” in China for many years. A few foundry enterprises using resin sand adopt the “resin sand used sand regeneration equipment” imported from abroad. Due to the low regeneration efficiency and high price (about 10 times the price of the same domestic regeneration equipment), ordinary enterprises are unable to accept it.
Sodium silicate is a kind of mold (core) sand binder with wide source, low cost and no pollution. It has been widely used in casting production. However, due to the problems of poor collapsibility and difficult regeneration of used sand in its mixed mold (core) sand, countries all over the world studied the collapsibility of sodium silicate sand in the 1980s and the regeneration of used sodium silicate sand in the 1990s, but it has not been well solved and has become a difficult problem all over the world.
This is because the water glass coating film on the outer layer of water glass sand contains certain bound water and is plastic. For the wet regeneration of sodium silicate, although the film removal rate is high, the investment in regeneration equipment is large, the sand needs to be dried after regeneration, and the alkaline sewage pollutes the environment; In the process of wind regeneration, the loss of old sand is large and the film removal rate is not high; For mechanical regeneration, it is generally considered that its film removal rate is low, and the utilization rate of used sand regenerated in molding sand mixture is low.
In recent years, “spiral vibration regenerator” and “friction regenerator” developed by Huazhong University of science and technology have avoided the shortcomings of the above equipment and solved the problem of old sand regeneration, especially the problem of old sand dry regeneration of sodium silicate sand. With less investment and high film removal rate, it provides a new type of used sand regeneration equipment for the foundry industry. Practice has proved that the effect is good, and the regeneration capacity can reach 20 tons per hour.