The quartz sand used in casting applications primarily consists of SiO2, accounting for over 92% of the sand's weight. The remaining 8% includes approximately 5% Al2O3, 0.5% Fe2O3, 0.2% CaO, and 0.1% MgO, among other metal oxides. Additionally, there is about 2% moisture and silt (feldspar clay, etc.). These oxides generally occur symbiotically with SiO2 in the quartz sand, some being present within the crystals, while others are associated as feldspar-like structures adhering to the surface of SiO2 crystals.

Quartz sand, combined with various high molecular weight resin organic binders, forms resin-coated sand with different characteristics. Due to the stable structure of SiO2 crystals, it possesses high resistance to high temperatures, making it suitable for most casting applications. Casting cores made from this material, when used for metal melting and casting, exhibit excellent dimensional stability and surface finish. After being used for casting, the resin-coated sand becomes waste casting sand. As the use of many resin-coated sands consumes significant amounts of sand and mineral resources, posing a serious impact on human life, how to recycle and reuse casting waste sand to reduce resource demand and environmental impact is a significant issue currently facing the mechanical industry.

Currently, the main methods for the regeneration of foundry waste sand involve thermal regeneration and mechanical impact regeneration techniques. There are also combined techniques that combine both thermal and mechanical impact regeneration. The characteristic of thermal regeneration is that the organic matter contained in the foundry waste sand is oxidized under high temperature conditions (with a calcination temperature of 600-800°C, or even higher), forming gaseous oxides that are removed from the surface or the sand collection area. This method is characterized by the fact that the surface of the regeneranted sand particles is very clean, with virtually all organic matter attached to the surface removed.

However, compared to mechanical conflict methods, the angle coefficient of the granules after regeneration remains unchanged, and the sphericality of the granules does not alter. The high-temperature calcination also enhances the chemical activity of the metal oxides adhering to the surface of quartz sand, forming various structures with relatively soft adherent materials. These adherent materials can affect the properties of the resin-coated sand for further use, such as bonding strength. The technical feature of mechanical conflict is that it uses mechanical equipment to impart a certain amount of kinetic energy to the sand particles at a relatively high speed, causing them to collide with each other or move relative to surfaces with a greater relative velocity. This results in relative frictional movement between the sand particles, stripping off the adherent organic matter, carbon, and metal oxides, with the aim of exposing new interfaces on the surface of the quartz sand particles.

This technique's characteristics include cost-effectiveness; after mechanical attrition, the particle angle coefficient changes relative to before, resulting in better sphericity. However, the newly再生 surface has more adherents, especially since the quartz sand particles themselves are uneven. Using this method alone is difficult to meet the requirements for reusing the sand in casting coating sand after regeneration, as it is generally only suitable for molding sand (such as shell mold sand, etc.). By combining thermal regeneration with mechanical attrition, it is clearly possible to achieve the purpose of completely removing organic matter through thermal calcination and improving the angle coefficient of the regenerating sand particles through mechanical attrition, thus enhancing sphericity. The quality of the newly regenerated sand is significantly better than when using either thermal or mechanical attrition alone. However, it still cannot completely remove impurities (adsorbed dust, foreign matter, etc.) within the uneven凹坑 of the sand particles.