Assessment of the effect of microsilica additive on the properties of refractory materials for steelmaking ladles

Currently, the operation of pouring devices and ladles in the metallurgical industry is attended with a number of challenges associated with the presence of impurities in steel with a significant temperature difference during pouring and casting of metal. These factors can significantly degrade the quality of steel, reduce the service life of equipment and increase the cost of its repair and replacement. Rapid changes in temperature cause local thermal stresses in refractory materials, which leads to the formation of cracks in the lining and metal parts of the equipment, as well as to deformation due to uneven heating and cooling, which disrupts the geometry of the equipment and reduces its functionality. Silicon production waste in the form of small particles of SiO2 (microsilica) are a promising material for modifying the structure of refractory materials due to their unique properties. The prospects for the use of SiO2 in refractory materials used for steelmaking ladles are considered. The effect of microsilica on the physical, mechanical and thermal characteristics of refractories, as well as the advantages of its use in high-temperature steelmaking processes, have been studied. It has been found that adding up to 4-6% SiO2 to the composition of refractory products increases strength, reduces porosity, and decreases the proportion of the decarburized layer and oxidation. Testing of samples has shown that the use of SiO2 in steelmaking conditions contributes to the formation of more stable and dense structures in refractory materials, which increases their resistance to thermal and chemical actions. It is assumed that the strengthening effect is achieved due to the polymorphic transition of SiO2, which increases the area of the developed surface and ensures contact adhesion of particles to each other, and when interacting with carbon at temperatures above 1500 °C, silicon carbides are formed, which are more resistant to oxidation. The use of microsilica in refractory materials for steelmelting ladles will reduce the frequency of repairs and periods of lining replacement, as well as increase the productivity of steelmaking, reduce costs by increasing their service life.