A New Permanent Layer Refractory Castable for Improving Ladle Insulation Performance

August 29, 2022

Ladle is an indispensable container in the steelmaking process. With the continuous development of smelting technology, especially the treatment of LF and RH outside the furnace, its role has developed from the simplest holding molten steel to a furnace that undertakes certain smelting functions. The long-term stay of the molten steel in the ladle will inevitably cause the loss of the molten steel temperature, and the high thermal conductivity of the lining will lead to increased heat dissipation loss of the molten steel, more serious deformation of the ladle shell, and increased temperature drop rate of the molten steel, resulting in serious slag hanging on the wall of the ladle. Nodules, cold steel.

 

Excessive low temperature, even forcing the tundish to stop the final pouring, not only affects the quality of the slab, but also lowers the yield of molten steel and increases the production cost. Therefore, the thermal insulation ladle has increasingly become the demand of steel mills. The structural mode of thermal insulation ladle refractory is usually light insulation board or nano-board + permanent layer castable + working layer refractory.

 

The insulation board with the most thermal insulation function itself needs a layer of refractory material to protect it. This material should protect the insulation material from too much pressure, and secondly, it should protect the insulation material from exceeding the operating temperature (if it must be below 1000 ℃), then the ladle will be permanent. Layer castables are such important materials. The ideal permanent layer refractory material for thermal insulation ladle should have good thermal stability, thermal insulation, corrosion resistance, safe and reliable application, complete structure and long service life. In order to maintain the good thermal insulation performance of the ladle and reduce the temperature drop of molten steel, in this work, the performance evaluation of the new CA6 castable and light mullite castable was carried out respectively, and the application on the ladle achieved a relatively good comprehensive performance. Insulation effect.

 

1) Raw materials and test plan

 

The main raw materials used in this experiment and their chemical compositions are shown in Table 1.

 

Table 1: Chemical composition of main raw materials

 

Among them, the CA6 raw material (CaAl12O19, abbreviated as CA6) is the calcium aluminate phase with the highest content of Al₂O₃ in the CaO-Al₂O₃ system. Its melting point is 1875°C, the thermal expansion coefficient is 8.0×10-6°C⁻¹, and the bulk density of the particles is 2.70g· cm⁻³, the apparent porosity is 26.8%. The refractory performance of this material is similar to that of tabular corundum, and the thermal conductivity is only 1/3 of that of corundum. It is a new type of high-quality thermal insulation material that has emerged in recent years. CA6 castable is made of CA6 as aggregate, and the matrix part is made of tabular corundum fine powder, alumina powder and calcium aluminate cement as binder. The bulk density of spherical light mullite particles is 1.59g cm⁻³, and the apparent porosity is 38.9%. The light mullite castable is made of microporous M70 spherical light mullite balls as aggregate, and the matrix part is made of tabular corundum fine powder, alumina powder and calcium aluminate cement to ensure Better resistance to slag erosion to improve the safety of the permanent layer.

 

2) Test process and performance testing

 

The physical properties test and corrosion resistance test were carried out for the two kinds of castables after casting. The physical test methods are carried out according to the national standard or industry standard method.

 Home  Whatsapp  Mail  Inquiry