Question

In a certain factory, iron is extracted from the haematite ore using the blast furnace as shown in Figure 1. The other raw materials are coke, limestone and air. The melting and boiling points of iron are 1535°C and 3000 °C, respectively.
         
                                Figure 1

1. State how the temperature in region I compares with that in region II. Give a reason. 
2. The main reducing agent in the furnace is carbon(II) oxide formed by the reaction
   CO₂(g) + C(s) →2C0g)
   Write two equations to show how carbon(IV) oxide is formed in the furnace.      
3. Suggest a value for the temperature in region III. Give a reason. 
4. Name the main component in the slag. 
5. State one role that slag plays in the blast furnace. 
6. The iron produced in the blast furnace is brittle due to presence of impurities
   • Name the main impurity in this iron 
   • State one use of this iron  
7. Recycling is one method used to reduce production costs. State and explain the by products that can be recycled in this factory.   

Answer 1

1. Temp. in region I is lower than that in II 
   Reason: 
   • Raw materials are not pre-heated  
   • Region II is nearer to hot air blast that pre-heats
   • Hot air raises in the furnace it becomes cooler
2.    
   • C(s) + O₂(g) → CO₂(g)  
                           Heat
   • CaCO₃(g)     CaO(s) +CO₂(g) 
                       (condition)
     Fe₂O₂(s) + 3CO(g) → 2Fe(l) + 3CO₂(g)
3. 1535°C - 3000°C 
   Reason
   • Helps maintain Iron molten state. 
4. Calcium Silicate/ CaSiO₃
5. Prevents oxidation of iron by hot air .
6.   
   • Carbon
   •   
     • Making manhole covers
     • Making scissors
     • Bunsen burner bases
     • Making iron pipes
     • Electric poles
     • Fire grills
     • Manufacture of steel
     • Manufacture of building blocks
     • Electric fence arch
7.   
   • Waste gases
     • used to preheat the air blasts 
   • CO₂(g)
     • used to preheat the air blasts.  
     • CO2 is converted to CO. Used as a reducing agent
   • CO(g)
     • used as a reducing agent 
     • used to preheat air blasts.