Introduction of refractory materials for melting aluminum and holding furnaces, damage mechanism and solutions

First, the main mechanism of refractory damage is as follows:

①Aluminum liquid adheres to the surface of AL2O3-SiO2 series refractories, and the following reactions occur:
AL plus SiO2→AL2O3 plus Si

The refractory material is deteriorated and loosened until it is damaged, and at the same time, the reduced Si enters the molten aluminum to change the composition of the aluminum material;

②The molten metal infiltrates into the pores of the refractory material, increases the contact surface with the refractory material, and changes the composition of the refractory material. When the penetration reaches a certain depth, the reaction of AL and SiO2 is accompanied by the reaction of the refractory material, which will cause the structure of the refractory material to peel off and damage the molten pool;

2. Solutions and reasons
1, in terms of materials

①High-tech castables include: low-cement, ultra-low-cement and cement-free castables, which are characterized by dense (low porosity), high strength, low temperature, medium temperature and high temperature strength, and the strength increases with the increase of temperature. Increasing; In addition, the volume of high-quality castables is very stable at various temperatures;

②By adjusting the particle size, peak size and type of the ultrafine powder added to the castable, and adopting measures such as "closest packing" of multi-stage ingredients, the porosity of the castable is reduced to less than 10 percent, and the average pore distribution is only 0.5 μm. However, the average pore distribution of traditional refractories such as phosphoric acid or aluminum phosphate as a binder is 22 μm; generally speaking, it is difficult for aluminum liquid to penetrate pores smaller than 0.5 μm, so low cement castables will replace the traditional traditional binder such as phosphate. refractory material;

③ In this low porosity and low average pore distribution low cement castable, composite additives that resist the penetration of molten aluminum are also added, which can increase the wetting angle of molten aluminum to the refractory material and enhance the resistance of the castable.

The effect of aluminum liquid penetration performance is very obvious.

Effects of additives on resistance to penetration of molten aluminum

2, structural aspects

①Add aluminum ingots or waste materials into the furnace from the furnace door, which is easy to hit the furnace door and the top of the furnace door. It is recommended to use the high-strength and low-cement castable QT-FHA.QT with heat-resistant steel fibers on the furnace door and the top of the furnace door. -FHA is a refractory material prepared by adding stainless steel heat-resistant fibers containing nickel-chromium and other alloy elements, appropriate explosion-proof agents and special additives on the basis of low-cement castables. It is characterized by high strength, good toughness, impact resistance, Thermal shock resistance, peeling resistance, erosion resistance, penetration resistance, etc. Performance performance in an environment below 1200 degrees Celsius. Experiments show that its strength is 30-60 percent higher than that of ordinary high-alumina castables without steel fibers at 1000 degrees Celsius.

②The top of the furnace must choose a castable with good volume stability and high structural strength at high temperature. Considering energy saving and consumption reduction, the bulk density of the castable should be as small as possible.

③Apply light-weight castables, light-weight bricks, light-weight thermal insulation mortar, aluminum silicate fiber products and other light-weight thermal insulation materials to the entire kiln for sufficient thermal insulation to reduce energy consumption and meet the needs of use.

3. Product performance indicators and use parts (see attached table)

Performance table of refractory materials for melting aluminum and holding furnaces

BuyFurnace lining, Quantong Kiln Industry, professional manufacturer