Mineral Composition/Phase of Ceramic Sand


In a sense, foundry sand such as corundum sand, silica sand, and chromite sand belong to refractory materials used in the foundry industry. Its properties are mainly determined by its chemical composition and mineral composition (mineral phase),  and are also affected by the material formation process conditions, particle size distribution, and application scenarios. Understanding and controlling the mineral composition of foundry raw sand is of great significance.

 

Overview of Ceramic Sand

Ceramic sand, scientifically known as "fused ceramic sand for foundry", is a calcined bauxite with alumina (Al2O3) as its main component, which is melted, sprayed, and sieved to produce different particle sizes of sand for foundry. The main chemical components of ceramic sand are alumina (Al2O3) and silica (SiO2), as well as a small amount of other metal oxides.

 

Chemical Composition Analysis of Ceramic Sand

From thechemical composition point of view, ceramic sand belongs to the aluminum silicate refractory material. Mullite phase is the only stable binary compound in the Al2O3-SiO2 system, and its composition can vary between 3Al2O3•2SiO2 and 2Al2O3•SiO2. Mullite has the following excellent properties: high refractoriness (1870℃); low thermal expansion (20~1000℃, 5.3×10-6/℃), excellent thermal shock resistance; good chemical resistance, excellent creep resistance. Mullite phase is one of the inherent foundations of aluminum-silicate special sand with excellent casting performance.

 

Corundum, whose main component is Al2O3, has various crystal forms such as α, γ, and δ. α-Al2O3 is the stable crystal form and belongs to ionic crystals.  The oxygen ions are arranged in a hexagonal closest packing, with small particle spacing and a strong structure that is not easily destroyed.  Corundum has high hardness (Mohs hardness of 9), a melting point of up to 2053℃, stable chemical properties, and good resistance to erosion from acidic, basic slag, metal melts, and so on.

 

Analysis of mineral facies composition of high-quality ceramic sand

High quality ceramic sand is made of bauxite with Al2O3 content ≥ 72%, which is melted by graphite electrode arc. The molten liquid will flow below the graphite electrode, be discharged from the drainage hole, and then be atomized (wind crushing or spray quenching). In the air, due to the surface tension of the liquid, it becomes spherical particles, and after rapid cooling, it becomes artificial sand. Due to rapid cooling and insufficient crystallization, there is a relatively high amount of residual amorphous material. This type of precious ceramic sand is heated, insulated, fully crystallized, and significantly reduces the glass phase, resulting in a mineral structure corresponding to "mullite + corundum + a small amount of glass body".

 

High-quality Ceramic Sand Manufacturer

Sanmenxia Qiangxin Foundry Materials Co., Ltd. has been developing and producing ceramic sand for more than 20 years, and we can control the quality of ceramic sand in all aspects.  Awaiting your contact and cooperation.