Fused ceramic sand (commonly known as "ceramic sand") is calcined bauxite with aluminum oxide (Al2O3) as the main component, which is melted, blown and screened to produce sand with different particle sizes for foundry. The product has compact structure, spherical shape, smooth surface, and has the advantages of high refractoriness, good air permeability, nice collapsibility, well acid and alkali resistance, low crushing rate and high regeneration performance.
Production Process of Fused Ceramic Sand
Calcined bauxite was added into the electric arc furnace (the size of the furnace is 650-850mm cube) 65-80% Al2O3 bauxite raw materials are melted into liquid by using the high temperature generated by arc discharge. When the liquid flows out of the furnace, 70-85m/s air pressure (pressure 3.0-8.0kg/cm3) is applied to it. After the liquid raw materials are crushed and cooled by strong wind, spherical or nearly spherical sand particles with smooth performance are obtained.
Main Features of Fused Ceramic Sand Products
1. Spherical particle shape: the particle shape is spherical, the surface is smooth and the surface area is small, and the fluidity and filling property are excellent. Therefore, it can obtain good sand mold strength and high air permeability and reduce the amount of binder compared with other molding sands. It also has good collapsibility.
2. Low thermal expansion rate: the thermal expansion rate is lower than that of other casting sands. Therefore, the production of castings has high dimensional accuracy, less cracks and defects, and high casting yield.
3. good crushing resistance: the fused porcelain sand is compact in volume, high in strength, and rarely broken in repeated recycling, which greatly improves the recycling rate of molding sand, reduces the discharge of waste sand, and is conducive to environmental protection.
4. High refractoriness: the main component is aluminum oxide, with neutral pH value. It is an aluminum silicon refractory with good fire resistance and can meet the casting requirements of various metals and alloys.
5. Low bulk density: the bulk density is less than chromite sand and zircon sand, thus reducing the cost of using high-quality molding sand.
Application of Fused Ceramic Sand in Sodium Silicate Self-hardening Sand Process
Basic information: amount of binder addition: 1.8%. Molding time: 40 minutes, sand iron ratio: 1:5, production batch: 400 tons/month.
The above figure shows the fused ceramic sand fully automatic molding production line of a sodium silicate manufacturer, which has two 5-ton electric furnaces (sets), using mechanical reclamation and wet reclamation.
Effect Comparison between Fused Ceramic Sand and Silica Sand
Product | Service Time | Refractoriness | Collapsibility |
Silica Sand | ＜5min | Low Refractoriness, sand sticking happens in several places of the castings | The collapsibility is poor, and there is sintering of large molding sand, which increases the workload of workers. |
Fused Ceramic Sand | 40min | High Refractoriness, no bad effects | Good collapsing and easy sand cleaning |
Advantages of Fused Ceramic Sand in Self-hardening Sodium Silicate Process
(1) The utilization of Ceramic Sand as molding sand can reduce the amount of binder content. While the strength is more than 30% higher than that of silica sand.
(2) Spherical sand with good fluidity, which can improve the defect of poor collapsibility in sodium silicate process.
(3) High refractoriness, >1800 ℃. It is especially obvious in the production of castings with thick surface, which can obviously reduce the common defects such as burn-on and metal penetration
(4) PH value appears neutral, it can meet the production of castings of various materials.
(5) Easy for recycling. The hardness of ceramic sand is much higher than that of silica sand. It will not be broken during mechanical reclamation. It can improve the reclamation rate of base sand, save costs and reduce the discharge of solid wastes.
(6) Improve the quality of castings. Ceramic sand is in point contact with the casting surface, which can effectively improve the surface quality of the castings.