Study On The Erosion Mechanism Of Refractories Containing Carbon For Ladle Lining

The residual ladle lining of Panzhihua Iron & Steel Co., physicochemical properties of slags, and the ladle lining refractory after slags corrosion test were investigated based on the study of refractories containing carbon for ladle lining at home and abroad and ladle refining conditions of Panzhihua Iron & Steel Co. in this paper. The erosion mechanism of MgO-C bricks with different carbon contents for ladle lining was studied as the main point. The results are obtained as follows.(1) Both MgO-C bricks for slag line and Al₂O₃-MgO-C bricks for package wall could be divided into three layers from the working face to the center: decarburization layer, transition layer, original layer. But both microstructures of layers of them are very different. There are a lot of low-melting-point compounds CMS and the complex glass phase containing calcium aluminosilicate mainly which located in decarburization layer of MgO-C bricks. The quantity of high-melting-point compounds MA is a little, and it is surrounded by liquid. The organization structure of decarburization layer of MgO-C bricks is loosen. There are a lot of high-melting-point compounds MA in decarburization layer of Al₂O₃-MgO-C bricks, which leads to more density of organizational structure of decarburization layer.(2) The content of TFe,V₂O₅ of the converter slag are high. The basicities of the high,middle and low carbon steel slags change a lot. The flowing-point temperature of the converter slag is lower than the other three slags. The XRD results show that converter slag was at amorphous state partly, and the others were at Mg-Al spinel, aluminum calcium silicate, calcium and magnesium olivine and complex solid solution form.(3) The degree of slags erosion of MgO-C bricks is as follows: the converter slag, high-carbon-steel slag, low-carbon-steel slag, mid-carbon-steel slag. The degree of slags erosion of low-carbon MgO-C bricks is as follows: the converter slag, mid-carbon-steel slag, high-carbon- steel slag, low-carbon-steel slag. It suggests that the law of erosion levels is Similar for each kind of slags, and the degree of bricks are as follows: MgO-C bricks, Al₂O₃-MgO-C bricks, low-carbon MgO-C bricks.(4) The organization structure of MgO-C bricks is loosen after decarburization, besides there is a lot of low melting point CMS,calcium aluminosilicate . They form continuous phase, which infiltrate into MgO grain boundary, leading to the decomposition of MgO and ultimately accelerate the damage to MgO-C bricks. However, a lot of micropores form in low-carbon MgO-C bricks after decarburization, and the high melting point MA is easy to supersaturate and deposite in the micropores. Therefore it enhances the degree of solid-solid direct bonded, which leads to the high density of organizational structure of decarburization layer. Therefor it prevents slags penetration to bricks and refractories dissolved in slags. Then it improves the material properties of resistance to slags erosion.