1. Introduction and Characteristics of Fused Ceramic Sand
Fused ceramic sand is a kind of artificial sand with excellent performance. Generally, high-quality raw materials are selected and placed in the electric furnace. When the molten liquid flows out of the furnace, it is blown away with compressed air flow. After cooling, spherical or nearly spherical particles are obtained with smooth surface.
The particle shape of fused ceramic sand is spherical or nearly spherical, and its color is black brown. The particle size is 0.053 ～ 3.35mm (270 ～ 6 mesh). Customers can make specific provisions on the particle size distribution according to their own process requirements.
Chemical Composition | Grain shape /angle coefficient | Bulk density | Mohs hardness | Refractoriness | Coefficient of thermal expansion (20~600。C) | pH |
Al2O3≥70% Fe203≤2.5% | Spherical /1.06 | 2.0g/cm3 | 7.5 | ≥1800°C | 7.2*10-6/K | 7.2~7.6 |
2. Characteristics and existing problems of modified ester self-hardening sodium silicate
The modified ester hardened sodium silicate self hardening sand process is a new generation of self hardening sand process developed on the basis of the raw water glass sand process. It uses a new type of sodium silicate with high strength and low viscosity and a special ester curing agent. Through the ion activation treatment of the sodium silicate bonding system, the sodium silicate sand is resinified, the process performance of molding sand is improved, and the collapsibility of molding (core) sand is improved.
The modified ester hardened sodium silicate process has the following advantages:
(1) Low binder addition and adjustable hardening speed
(2) Molding sand has good technological performance and good hardness and permeability in winter
(3) The casting has high quality and dimensional accuracy, good molding sand thermoplastic and low gas evolution, which can prevent cracks and porosity defects in the casting
(4) No irritation, harmful gas generation, friendly to on-site workers, etc.
But at the same time, the modified ester hardened sodium silicate also has the following disadvantages:
(1) The sand bursting property of molding sand is poor to organic resin binder
(2) It is difficult to recover the used sand. There is harmful waste water generated in wet regeneration, and the recovery effect of dry regeneration is not ideal
3. Advantages of fused ceramic sand in modified ester self-hardening sodium silicate process
(1) The use of fused ceramic sand as molding sand can reduce the amount of binder, and the strength of ceramic sand is more than 30% higher than that of silica sand under the same amount of binder.
(2) The spherical sand has good fluidity, which can improve the defect of poor sand breaking property of sodium silicate process.
(3) High refractoriness, ceramic sand refractoriness >1800 ℃, especially in the production of castings with thick surface and more heat savings, which can significantly reduce the tendency of sand sticking and iron clad sand.
(4) Neutral sand can meet the production of castings of various materials. Silicon sand is acidic, and it is easy to produce chemical sand sticking when producing high manganese steel and other alkaline castings. Fused ceramic sand is a neutral sand, which is not easy to react with the alloy in the molten metal
(5) Easy for recycling. The hardness of fused ceramic sand is much higher than that of silica sand, and it will not be broken during mechanical regeneration. It can improve the recovery rate of used sand, save costs and reduce solid waste emissions.
(6) To improve the quality of casting products, the fused ceramic sand is in point contact with the casting surface, which can effectively improve the surface quality of castings.
4. Specific Case
Liaoning Dapeng heavy equipment manufacturing Co., Ltd. used our fused ceramic sand to replace silica sand in the production of sodium silicate process in May 2021.
The left side is silicon sand casting, and the right side is ceramic sand casting
The first layer is the test product, and the second layer is the previous product.
5. Fused ceramic sand is easier for reclamation
Regeneration outline: Mechanical regeneration + wet regeneration
1. mechanical regeneration: conventional is single-stage mechanical regeneration, with 10-15 cycles.
2. wet regeneration: after 10-15 times of mechanical regeneration, one wet regeneration is required to fully remove the residual sodium on the surface of fused ceramic sand.
3. drying: fused ceramic sand after wet regeneration needs to be dried before entering the sand warehouse.
Summary: the regeneration plate is the top priority of ceramic sand ester hardening process, which needs to achieve: effective operation of equipment and scientific management of operation process.
6. Overall Advantages of using Fused Ceramic Sand
The use of ceramic sand in modified ester self-hardening sodium silicate process can improve the casting quality, reduce the comprehensive cost of customers, reduce the discharge of solid waste, and achieve quality improvement, cost reduction, green, environmental protection.