Brief introduction of AOD refractories

The working characteristics of AOD furnace are as following,
1. High working temperature. To reduce the carbon content of the steel to a very low level, the refining temperature should be raised above 1700*C.
2. Strong stirring of molten steel. The injection of large amounts of high pressure gas causes the molten steel to churn violently.
3. The alkalinity of the slag varies greatly.
4. Intermittent operation.
The working process of AOD furnace is to first blow oxygen decarburization, then add ferrosilicon or aluminum to reduce chromium in slag, and then add lime desulfurization. In the whole process of smelting, the slag changes from acidity to alkalinity, and the atmosphere also changes from silicon oxide atmosphere to reducing atmosphere.
Due to the above working characteristics, the refractories of AOD furnace are required to be high, high temperature strength. Good thermal shock resistance and slag resistance. Especially for the tuyere and the area around tuyere more need to use corrosion resistance and good resistance to flaking refractories. The refractories commonly used in AOD furnace mainly include magnesia-Chrome brick and Magnesia-Dolomite brick, among which magnesia-chrome brick is mostly pre-synthesized magnesia-chrome brick and recombined magnesia-chrome brick. In order to form a balanced furnace lining, the upper part of the tuyere is fused with magnesia-Chrome brick, and the other parts are directly combined with magnesia-chrome brick, or the tuyere part is pre-reacted magnesia-chrome brick, and the rest parts are magnesia-dolomite brick. The top part of the furnace can be high alumina refractory castable and refractory plastic, but also can be built with magnesia brick. Due to the environmental pollution of magnesia-chrome brick, the development trend of which refractories are used in AOD furnace is that the use of magnesia-chrome brick is less and less, and magnesia-calcium refractories are more and more. Some AOD furnaces use low-carbon magnesia-calcium materials, such as bitumen combined dolomite brick, resin combined dolomite brick. The resin combined with dolomite brick is heated for a long time to improve and deepen the coking of furnace lining so as to reduce the carbon absorption of molten steel.