Conventionally Al_2O_3-MgO-C (AMC) refractories are used in ladle metal zone and bottom due to its abrasion resistance and thermal expansion characteristics. Al_2O_3-MgO-C is not used in areas like steel ladle slag lines because the primary alumina materials are very susceptible to basic slag and thus show poor slag corrosion resistance. But in some cases, due to particular plant shop logistics, the left-over basic slag of the ladle comes in contact with the bottom and lower barrel bricks and corrodes AMC bricks heavily. Here slag corrosion resistance property becomes a foremost issue in the bottom and lower barrel bricks for determining the ladle performance. The slag corrosion resistance can be improved either by increasing the graphite content or by increasing the magnesia constituent of the AMC brick. Increase of graphite is restricted as it increases the thermal conductivity of the brick resulting to more heat loss and increase in ladle shell temperature. Increase of Magnesia, on the other hand, increases the rate of spinel formation (MgAl_2O_4) resulting very high thermal expansion. The present paper describes the development of a new generation AMC brick that has been formulated to optimize the slag corrosion resistance as well as the thermal expansion properties by controlling the refractory non-wettable characteristic through graphite amount and thermal expansion characteristic through the granulometry, quality and quantity of magnesia part. Such AMC bricks have been manufactured in our plant and used in a 300 ton ladle in Japan and found encouraging performance.
展开▼
