Crude steel is produced in a blast furnace by using a mixture of hematite ores, metallurgical coke, and fluxes. Hot air is also purged in the BF. For 1000 kg of ores, we use 250 kg of metallurgical coke.
- The hematite ores contain 50.3 wt.% Fe (as Fe2O3 form) and SiO2 as the remaining part.
- The metallurgical coke has fixed carbon as 80.0 wt.% and the rest is SiO2 as ash.
- Pure CaCO3 is used as flux.
16% excess air is used to burn the remaining carbon (some of C will go to the alloy) to produce CO(g):
2 C + O2 (g) = 2 CO (g)
The reduction efficiency of Fe2O3 is 96%, and unreacted Fe2O3 will go into the slag as FeO. The reduction reactions of Fe2O3 are as follows:
Fe2O3 + 3 CO (g) = 2 Fe (in alloy) + 3 CO2 (g)
Fe2O3 + CO (g) = 2 FeO (in slag) + CO2 (g)
The composition of the crude steel is 1.6 wt.% Si, 2.3 wt.% C, and the rest is Fe. The reduction reactions of SiO2 and C are as follows:
SiO2 + 2 CO (g) = Si (in alloy) + 2 CO2 (g)
C = C (in alloy)
In the slag, the CaO to SiO2 weight ratio is 1.0. CaO and SiO2 are occurred due to this reaction:
CaCO3 = CaO3 (in slag) + CO2 (g)
SiO2 = SiO2 (in slag)
For the production of 1000 kg of alloy, please calculate:
a) Amount of the hematite ores, metallurgical coke, and fluxes (kg)
b) Volume of the hot air at STP (m3)
c) Amount and composition of the alloy (kg and wt.%)
d) Amount and composition of the slag (kg and wt.%)
e) Amount and composition of the off gas (m3 and vol.%)