The Erosion Mechanism Of Ladle Slag Lining Brick With Different Slagging Condition

The MgO-C brick is a basic composite refractory materials which has good thermal shock resistance and slag resistance.It is widely used as lining of the steelmaking converter,slag lining of the ladle,and refining furnace lining,and has made the remarkable progress.Application situation and analysis of physical and chemical properties of different kinds of MgO-C bricks and the end refining slag provided by TISCO,HISCO,WISCO and HWISCO were done.The microstructure and erosion mechanism of MgO-C bricks used in four different steelworks with different slagging condition were investigated by means of optical microscope,scanning electron microscopy and X-ray diffraction analysis.The results showed that it is easy for slag with high basicity penetrate in MgO-C bricks and dissolve MgO.Those slags have low viscosity at high temperature and penetrate in MgO-C bricks fast and result in serious erosion to MgO-C bricks.The viscosity of slag with high basicity fell index as the temperature rose.The lower the viscosity,the deeper the penetration of slag into block.That is,the higher the refining temperature was,the faster the refractories were eroded,the more serious erosion.The results of microstructural analysis and XRD showed that the reaction layer of used brick had a large number of pores.The content of graphite in this layer declined quickly and makes the formation of decarburized layer.Melton slag penetrates along the pore in matrix and grain boundary of magnesia.Those resulted that the magnesia particles dissolved and freed.Al₂O₃ in slag reacted with the brick to generate MA spinel layer at high temperature.The spinel layer protected the brick from erosion.The higher the content of the Al₂O₃ in slag,the better the brick has erosion resistance.The results showed that brick D has the most serious erosion and its effect is worst. This is because the slag D has high basicity and low viscosity.Melton slag is easy to penetrate into the inside of brick.MgO in the slag mainly come from the erosion of bricks.The content of MgO in slag D is the highest.Those also proved that brick D had serious erosion by the slag.Brick C was eroded slightly and had the best effect when used.It is consistent with the actual.On the one hand,the slag C has low basicity and high viscosity,which can prevent the high-temperature slag from the penetration of melton slag into brick.It can slow down the erosion of slag to brick.On the other hand, there is the highest Al₂O₃ content and the minimum content of MgO in slag C.At high temperature,Al₂O₃ reacted with MgO to generate MgO·Al₂O₃,MgO·Al₂O₃ can absorb FeO,MnO from the slag and formed the solid solution.That can prevent the slag from the penetration of melton slag into brick.In addition,because brick C had good physical properties,it had long service life.In order to study the slag resistance of brick with different matrix,corrosion testing for five different formulations of the crucible sample was made choosing slag A and D. The results were that sample 1# concluding fused spinel had the best physical properties. Fused spinel crucible sample had the best anti-erosion by means of the petrographical analysis.Fused spinel has the strongest ability of anti-erosion.In the course of use MgO·Al₂O₃ can absorb FeO,MnO from slag to generate solid solution.That resulted that the viscosity of melton slag rose and prevented further penetration of slag.Slag D had more serious erosion to samples than slag A.because the basicity of slag D is almost two times of slag A.Slag with high basicity had lower viscosity at high temperature.This can reduce the slag resistance of sample.