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Selection and application of refractories for AOD furnace


The AOD furnace method is a more advanced method in refining stainless steel. Because of its very simple equipment, low investment, convenient operation, strong adaptability, and low production cost, it will be widely used. The AOD furnace reduces the partial pressure of carbon monoxide by means of dilute gas position. As the high-pressure mixture of oxygen and hydrogen is blown into the furnace, air bubbles will come into contact with molten steel and slag more frequently, which will allow sulfur, carbon and non-metallic inclusions to be quickly removed. During the blowing smelting process, the nature and composition of the slag will change during the smelting process, and the change value of the alkalinity from the early stage to the late stage is about 0.6 to about 4.2, and the refractory material will also be corroded from strong acidity to strong alkalinity. erosion. Therefore, the AOD furnace uses refractory materials with high high temperature strength, good thermal shock resistance, wear resistance and erosion resistance.

1. Magnesium-chromium series refractories
Magnesia-chrome bricks are directly combined with high-quality high-purity magnesia and refined chrome ore calcined at high temperature. The microstructure of magnesia-chrome refractory bricks is the main combination of the main crystal phase, and the silicate with a low melting point will exist relatively isolated in it. It has the advantage of good slag resistance, and it is much better to use than the magnesia-chrome brick produced directly. Semi-bonded magnesia-chrome bricks have the comprehensive properties of direct bonding and rebonding magnesia-chrome bricks. The infiltration of slag is the main reason for the deterioration and shedding of the brick structure.

2. Magnesium-calcium series refractories
Due to the variety of raw materials and low price of magnesium-calcium series refractory materials, it has been widely valued by people. However, the easy hydration of this material makes its application also limited. The AOD furnace mainly uses fused unburned magnesia dolomite bricks and fired magnesia dolomite bricks as furnace lining materials. Fused non-burning magnesia dolomite is made by pressing fused magnesia dolomite sand under high pressure, and then placing it in a low-temperature drying place; while fired magnesia dolomite bricks are made of sintered magnesia dolomite sand with good quality It is pressed under high pressure, and then placed in an environment above 1600 Celsius for firing. Because the fused magnesia dolomite sand has been fully smelted, it is very stable and the crystal lattice is very complete, making it have strong anti-hydration and anti-erosion capabilities.

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