AOD is the refining equipment of argon oxygen decarburization. It’s named after the acronym of its English name. Its configuration is similar to converter which is set on a support ring tilting front ad back and is fixed with dowel. On the side bottom of the furnace, spray lances are set to blow gases towards the horizontal direction of the molten pool. The number of spray lance is different according to the tonnage of the furnace, generally 2-3. The extension cord of spray lance coincides with the vertical spindle of furnace. Spray is made up of inner pipe (copper) and outer pipe (stainless steel). Inner pipe is used to import the main blowing gases (made up of Ar-O2 or Ar-N2). Annular gap between inner pipe and outer pipe imports Ar, N2 or air to cool the spray lance. Spray lance is depletion type. It is imbedded into refractory layers when constructing furnace. It is burned up during the period of smelting synchronizing with furnace lining. The blown oxygen is used to heat carbon oxide. Blown argon is used to strong convection agitation. The blown nitrogen is used to alloy when producing high nitrogen alloy. Lots of metal nitride are saved during the production process of 21-4N kinds of steel. For example, the amount of chromium nitride is reduced and cost of production is saved a lot.
The furnace body is built by magnesia-calcium brick, chrome magnesium brick or magnesium dolomite brick. Higher quality of electric smelting chrome magnesium brick is used around the spray lance to bear scour of high temperature and molten steel. Removable furnace lid is built with chrome magnesium brick or alumina-magnesia brick. It also can be cast by heat-resistant concrete. Dimensional proportion of furnace hearth is pool depth: inside diameter: total furnace height = 1:2:3. In the situation of furnace tilting forwards a certain angle, the primary molten steel is poured into by swiveling ladle. At this time, pneumatic lance is on the surface of molten steel. When the furnace is back to the upright position, spray lance is submerged into the deep molten steel and begins to blow and refine. After refining, steel is still out from furnace lid.
