Sponge Iron

The main furnace used in the reduction process is the Rotary Kiln, which essentially a furnace, is a refractory lined, long inclined cylindrical structure, into which all the raw materials and reducing agent (coal) are fed, The kiln is injected with continuous hot air and oxygen at varying temperatures from all sides, depending on the temperature requirement. At startup, a light-up burner is used at the kiln discharge end, which is oil fired to heat up the kiln. Coal is then injected from the outlet of the kiln to ignite the kiln. Once the desired temperature is reached, iron ore, reduction coal and limestone (usually dolomite) are fed from the feed end. Since the kiln is inclined (2.5%) from the feed and downwards to the discharge end and keeps on rotating, the fed iron ore keeps on mixing with the coal. With the help of continuous oxygen injection the iron ore slowly gets reduced as it goes through the system. The rotary speed of the kiln is adjusted to suit the feed rate and the required percentage of metallization. The following chemical reactions take place in the kiln. C+O2= CO2 C+O2+ C = 22CO Fe2O3 +CO = Fe3O4+CO2 Fe3O4 +CO = FeO+CO2 FeO + CO = Fe (Metals)+CO2 Resulting in the following reduction chain: 2Fe2O3 -> 2Fe3O4 -> 6FeO -> 6Fe Reduction: (0%) (11%) (22%) (67%) -> 6Fe

More volumetric weight:Usually (10-100%) more than other types of scraps Known uniform composition:Less variations in chemical compositions Low sulphur and phosphorus levels. Low content of dissolved gasses. Foamy slag:Capability of gorming protective cover of foamy slag in the bath