Measures to improve the quality of castables for electric furnace steelmaking

December 14, 2018

Measures to improve the quality of castables for electric furnace steelmaking

Electric furnace steelmaking uses electric energy as a heat source for steelmaking. The electric furnace roof is initially made of silicon brick. After that, high-aluminum materials are tested. Its refractoriness, high-temperature corrosion resistance and thermal shock resistance are better than those of silica bricks. Therefore, it was used by steel mills for a long time. In order to reduce the stopping time and labor intensity, the overall process of refractory castables with high alumina or corundum and steel fiber is generally used in the position of the electrode triangle. In order to improve the quality of castables, we will start to improve from the following aspects:

(1) Raw materials with high purity, less impurities and good volume stability at high temperature are used to improve the high temperature volume stability and corrosion resistance of the castable.

(2) Minimize the amount of CaO, that is, the amount of cement used. Because the increase in CaO content will greatly increase the amount of liquid phase, which is detrimental to the high temperature performance of the castable.

(3) Adding appropriate amount of α-Al2O3 to increase the medium temperature strength of the material. Because α-Al2O3 reacts with CaO to produce CA and CA2, resulting in a certain volume expansion, which can compensate for the volume shrinkage of the castables due to dehydration and crystal transformation.

(4) Add an appropriate amount of soft clay as a sintering agent to promote the formation and sintering of the liquid phase in order to form ceramic bonding.

(5) Adding a certain amount of expansion agent (kyanite) to increase the volume shrinkage of the material during the sintering process by volume expansion formed by the smectite of the kyanite material.

(6) Adding heat-resistant stainless steel fiber to improve the thermal shock resistance of the material while enhancing the toughness of the material, reducing the structural spalling and damage of the castable.

(7) Add an appropriate amount of anti-explosive agent to facilitate the smooth discharge of water vapor in the castable to improve the baking quality of the castable.