Indian Institute of Technology, Kanpur
Department of Materials Science and Engineering
MSE 651A: Advanced Concepts in Ironmaking
Assignment 3
Full Marks: 45
Due Date: 27.02.2026 before noon
Question 1
A blast furnace using pure hematite (Fe2O3) as the feed is operated with 370 kg of oxygen (as air blast) and 450 kg of coke (assume pure carbon) per tonne of product Fe. The hot metal from the furnace consists of 5 wt.% C and the rest Fe.
Calculate the following:
(a) (O/C)g, nCA and nOB.
(b) The volume of air in Nm3 units required to produce 1 tonne of product Fe and the overall composition of the top gas including N2. Assume air behaves ideally and contains O2:N2 in the volume ratio 21:79.
Question 2
(a) Plot the operating line for the operation in problem 1 on an O/C versus O/Fe graph and check graphically your answer to part (a) of problem 1. Express your comparative answers in terms of the oxygen carbon ratio in the top gas, that is (O/C)g.
(b) The blast furnace operation in problem 1 is switched to an acid low SiO2 sinter in which the predominant oxide is Fe3O4. The low SiO2 content of this feed allows low slag production per tonne of product Fe which permits the operator to reduce coke and blast supplied to 425 kg of coke and 345 kg of oxygen per tonne of product Fe.
Demonstrate graphically the effects of this change and determine the mole fractions of CO and CO2 in the carbonaceous portion of the top gas (XCOg and XCO2g) for this new operation.
Use graph papers for problem 2(a) and 2(b).
Question 3
Derive the applicable form of the overall oxygen balance equation for a blast furnace if the feed and hot metal characteristics are changed as follows.
(a) Feed contains pure Fe3O4 and pure Fe2O3 in the molar ratio 1:3.
(b) Hot metal contains 4.5 wt.% C, 1.2 wt.% Si and 1 wt.% Mn.
Question 4
A hematite charged blast furnace is operating with a coke supply of 590 kg of carbon and a blast supply of 1850 Nm3 of air blast, both per tonne of Fe. The normal supply for high grade pellets to the plant is interrupted and the operators are forced to charge a low grade hematite ore to the furnace.
It is found that with this new ore the steady state carbon and blast supplies are 650 kg and 2200 Nm3 respectively, both per tonne of Fe.
By how much has the new low grade ore increased the heat demand of the bottom segment of the blast furnace? Assume the enthalpy provided by the blast is 17000 kJ per kilomole of oxygen in the blast. State any other assumptions you might need to make.
Question 5
In class we have derived the oxygen balance for the bottom segment of a blast furnace. Derive the applicable version of the oxygen balance equation for the top segment of a blast furnace under idealized conditions.
Assume that the feed is pure hematite (Fe2O3) with no gangue present.
Examine the consistency of the resultant equation. The relevant input and output for the top segment of the blast furnace are shown in the figure.
