Pig iron

Pig iron is a good charge material because of its

• High density
• Low melting point
• Carbon contribution
• No tramp elements

It must be known that EAF is designed exclusively to use electrical energy. Pig iron contains  and . Charging of pig iron means refining is to be done in EAF. For example if we make a charge mix containing 20% hot metal with 3.5%C and 80% scrap with 0.1%C to produce100 ton steel with 0.1% carbon. We need to remove around 640kgC. To remove this amount of carbon we would be needing  oxygen on the assumption that oxygen utilization is 100% and is used for removal of carbon only. Under actual conditions we would be needing more oxygen to remove carbon if we take into account oxidation of . More proportion of pig iron in charge mix will increase oxygen requirement. What we learn from this simple calculation is that one has to supply oxygen under EAF condition and has to handle large amount of CO as well. Extra decarburization will increase tap to tap time and may decrease productivity. Under practical condition 30%hot metal is suggested to give optimum results with regard to productivity, electric consumption etc. The source of hot metal is either blast furnace or smelting reduction process. Hot metal can only be used when EAF plant is in close proximity of the blast furnace or smelting reduction units, otherwise one has to use pig iron and extra energy would be required to melt the pig iron