A steel mill has a 180t top-bottom combined blown converter. The furnace lining is built by simple up-laying method, and the working layer is made of magnesia carbon refractory brick. The converter has been in operation since February 2009 and has been shut down for maintenance in March 2010. The furnace has reached 8,288 times. During the overhaul of the converter, it was observed that the damage of the lining was uneven, and the erosion rate of the local refractory material was faster. The lining erosion observed after shutdown is shown in Figure 1. The dotted line in the figure indicates the lining after shutdown. The specific conditions of erosion of various parts of the lining are summarized in Table 1.
Schematic diagram of converter lining damage
Table 1.Schematic diagram of converter lining damage
|Furnace cap||The working layer has a residual thickness of about 500 mm; the joint between the furnace body and the furnace cap is thin, and the residual thickness is about 100 mm.|
|Body||The front large face is about 150mm thick: the center of the rear large face is thin, the residual thickness is about 100mm, and there is residual steel in the north and south.|
|bottom||The residual thickness is about 450mm, and there are more residual steel at the bottom of the furnace.|
|Tape hole||The residual thickness is about 100mm, and there is a hole in the ramming material.|
|Slag||Residual thickness about 100mm|
|ear||Residual thickness is about 150~170mm|
|Gas brick||The residual thickness is about 450mm, and there are two bricks with refractory material falling off, only the steel gas pipe is left.|
|Molten pool||Severe erosion, grooved, residual thickness of about 150mm|
Analysis of the damage of the furnace lining shows that the corrosion rate of the magnesia-carbon brick at the joint of the furnace body and the furnace cap, the front and rear large faces, the slag line, the trunnion and the like is faster than that of the general working layer, and is a weak link of the furnace lining. The service life of the converter often depends on the weakest part of the furnace lining. There are many reasons for the damage of these parts, which are related to the comprehensive effects of various factors such as refractory quality, use conditions and production operation.The combination of the furnace body and the furnace cap changes, the transition from the cylindrical type to the round table type, and far from the bottom of the furnace, the effect of the slag splashing furnace is not good, the slag is difficult to cover the surface; plus the frequent periodic operation of the converter The temperature in the furnace fluctuates frequently. When the steel is poured or poured, the part is repeatedly washed and eroded by the molten steel and the slag, resulting in serious damage. The front and back of the furnace body are eroded and washed by molten steel and slag, and the front large surface is also impacted by molten iron and scrap steel during charging. The slag line is mainly slag corrosion, and it is seriously damaged on the slag discharge side. The trunnion is mainly affected by slag erosion, airflow erosion and mechanical stress, and the slag is less, and the magnesia carbon brick is easily oxidized.