Module 3: Unit Processes 1
  Lecture 28:Materials Balance in Iron making

Illustration

Let me illustrate material balance through a problem
Consider a blast furnace which is charged with iron ore coke and flux of the following composition:

Iron ore (weight %): Fe2 O3 =78, SiO2 -8.4, MnO = 0.6, Al2O3=5.0,
P2O5 = 1.7MgO = 1.2 and H2O=5.1
Coke (weight %): C=88, SiO2 =9, Al2O3 =1 and H2O = 2
 Flue : CaCO3=96 %, MgCO3 =2% and SiO2 =2%

Pig iron analyses  

The coke rate is 900kg/ton of pig iron. (Modern blast furnace operates with much lower coke rate)
During smelting 99.5% of Fe is reduced and 0.5% is slagged. The CO/CO2 ratio in the top gas is 2/1
Calculate

  1. Weight of iron ore
  2. Weight and composition of slag
  3. Volume of air required
  4. Volume and% composition of exit gas.

Solution:

Fe balance:  (0.995).(Fe in iron ore) =Fe in pig iron
Let x kg iron ore
 
 

      (a)  
   
Weight of slag:

Slag consists of

 in pig iron