Ladle Working Layer Castable

The refractory castables for the working layer of the ladle are made of corundum, magnesia-aluminum spinel, and fused magnesia as the main raw materials. They are made using micro-powder combination technology and additives. They have the characteristics of good construction performance, high strength, good volume stability, corrosion resistance, erosion resistance, and good thermal shock resistance. They are suitable for casting the walls of large and medium-sized ladles, and can also be made into cast bricks for use.

The refractory castables for the working layer of the ladle are high-purity aluminum-magnesium refractory materials based on high-purity synthetic raw materials. Since the promotion of this type of material in the late 1990s, it has been widely accepted by steel mills for its long service life, carbon-free, and low silicon oxide and iron oxide impurity content. High-purity aluminum-magnesium refractory materials, refractory castables for the working layer of the ladle mainly include corundum-spinel castables, corundum-magnesia castables, and unfired bricks, among which corundum-spinel castables are currently the most used.

 

Characteristics of refractory castables for the working layer of the ladle: The corundum-spinel castable uses calcium aluminate cement as a binder, spinel fine powder, magnesia fine powder, silica powder and other oxides supplemented with different additives as the matrix part, and spinel (melting point 2135℃) and corundum (melting point 2050℃) as aggregates. The castable has strong wear and erosion resistance and good chemical stability, thus avoiding carbon increase in molten steel or adverse effects on the total oxygen content of molten steel. At the same time, it performs relatively well in slag resistance and thermal shock resistance.

Corundum-spinel castable, commonly known as "aluminum-spinel castable". It is a new type of refractory castable for the working layer of the ladle. As the lining of the ladle, magnesium-aluminum spinel has the effect of preventing slag penetration and resisting structural peeling. The self-flowing corundum-spinel castable made of this material as the main material is used on the ladle, and its corrosion resistance is equal to or higher than that of the vibrating castable of the same material. In China, corundum-spinel castables have also achieved good results as seat bricks and iron hook castables for ironmaking.

The refractory castable for the working layer of the ladle uses spinel as a fine powder ingredient, and the castable has better resistance to slag erosion and penetration. The reasons are:

1. The fine powder of spinel can absorb a large amount of iron oxide in the slag, solidify the iron oxide, and slow down the penetration of the slag

2. Ca0 in the slag and AL203 in the fine powder form needle-shaped objects, which make the pores fine and inhibit the penetration of the slag;

3. Make the enriched SiO2 liquid phase viscous and inhibit the penetration of the slag.

In addition, modifiers are added to the castable to activate the AL203 lattice and form a solid solution with AL203, which is beneficial to the sintering of AL203 and thus improves the thermal shock resistance of the material.

There is no big difference between self-flowing castable and vibrating castable in terms of basic components. The reason why self-flowing castable can flow without external force is that the repulsion force between the micro-powder particles with different charges inside it is generated by adding deflocculating agent (suspending agent) to generate flow. Therefore, the hardening mechanism of corundum spinel self-flowing castable is consistent with that of corundum spinel castable, and it is still jointly acted by hydration bonding and coagulation bonding.

Self-flowing refractory castable is characterized by its fluidity after mixing. Castables with this fluidity can flow and degas without artificial external force. Compared with ordinary castables, it has the following characteristics:

1. Self-flowing, it can flow without vibration under the action of its own weight;

2. Self-leveling, self-leveling when there is a guide plate;

3. The surface of the construction body is flat;

4. It is pumpable;

5. The construction time is short, there is no noise, and the working conditions are good.

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