High Alumina Slag and Blast Furnace Operation May27

High Alumina Slag and Blast Furnace Operation...

High Alumina Slag and Blast Furnace Operation Blast furnace (BF) process of iron making is a process where liquid iron (hot metal) and liquid slag are produced by the reduction of iron bearing materials (sinter and/or pellet and lump ore) with coke and by fluxing of the gangue material of the feed materials. The process is the result of a series of chemical reactions which takes place in the blast furnace. The separation of slag from the hot metal takes place in liquid state. Slag has a lower melting point and is lighter than hot metal. In the blast furnace it is at a higher temperature than the hot metal. Blast furnace slag contain predominantly silica (SiO2), alumina (Al2O3), lime (CaO) and magnesia (MgO) along with smaller amounts of FeO, MnO, TiO2, Na2O, K2O and S. Blast furnace (BF) slag composition has very important bearing on its physicochemical characteristics which influences to a great degree the smooth operation of the blast furnace, slag handling, coke consumption, blast furnace productivity and the quality of the hot metal. Low alumina slag normally has low viscosity, high sulphide capacity and low liquidus temperature as compared to high alumina slag. Blast furnace slag alumina (Al2O3) is mainly dependent on the alumina content of the input materials mainly iron ore. In those cases where iron ore alumina is less than 1 % the alumina content in the slag hardly goes above 10 %. But in some iron ores (normally found in India) alumina content is 2 % and higher. Such ores raise the alumina levels in blast furnace slag to 20 % and higher. To operate a blast furnace with such high alumina slag is quite difficult and need a different type of skill from the blast furnace operators...