BLAST FURNACE

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• Q1: What is a Blast Furnace?
  Ans: A blast furnace is a large vertical furnace used to produce pig iron from iron ore.
  It works by heating the ore with coke and limestone using a blast of hot air.
• Q2: State any four uses of Blast Furnace.
  Ans: The uses are:

  • ➔ Production of pig iron
  • ➔ Extraction of iron from ore
  • ➔ Production of slag for cement
  • ➔ Supply of raw material for steel making
• Q3: Briefly explain the working of a Blast Furnace.
  Ans: In a blast furnace, iron ore, coke, and limestone are fed from the top.
  Hot air is blown through tuyeres at the bottom.
  Coke burns to produce heat and carbon monoxide.
  The ore is reduced to molten iron, and impurities form slag.
  Molten iron collects at the bottom and is tapped out.
• Q4: Name some parts of the Blast Furnace.
  Ans: The main parts are:

  • ➔ Throat
  • ➔ Stack
  • ➔ Bosh
  • ➔ Hearth
  • ➔ Tuyeres
  • ➔ Bustle Pipe
  • ➔ Slag Hole
  • ➔ Bell and Hoppers
• Q5: What is the purpose of Throat in Blast Furnace?
  Ans: The throat is the top part of the furnace.
  It is used to feed raw materials and prevent gas from escaping.
• Q6: What is the purpose of Bosh in Blast Furnace?
  Ans: The bosh is the widest part of the furnace.
  It helps in the accumulation and melting of materials.
• Q7: What is the purpose of Tuyeres in Blast Furnace?
  Ans: Tuyeres are nozzles through which hot air is blown into the furnace.
  They help in combustion of coke.
• Q8: What is the purpose of Bleeder Valves in Blast Furnace?
  Ans: Bleeder valves are used to release excess gas pressure from the furnace.
  They ensure safety during operation.
• Q9: What is the purpose of Bustle Pipe in Blast Furnace?
  Ans: The bustle pipe distributes hot air uniformly to all tuyeres.
  It surrounds the furnace.
• Q10: What is the purpose of Bell and Hoppers in Blast Furnace?
  Ans: Bell and hoppers are used to feed raw materials into the furnace.
  They prevent escape of gases while charging.
• Q11: What is the purpose of Slag Hole in Blast Furnace?
  Ans: The slag hole is used to remove molten slag from the furnace.
  It is located above the iron tapping hole.
• Q12: What is the purpose of Hearth in Blast Furnace?
  Ans: The hearth is the bottom part of the furnace.
  It collects molten iron and slag.
• Q13: What is the purpose of Stack in Blast Furnace?
  Ans: The stack is the middle part of the furnace.
  It helps in preheating and reduction of iron ore.
• Q14: What is the purpose of Uptakes in Blast Furnace?
  Ans: Uptakes are passages that carry hot gases from the furnace to gas cleaning systems.
  They help in utilizing waste gases.
• Q15: What is the purpose of Turbo Blower in Blast Furnace?
  Ans: A turbo blower supplies high-pressure air into the furnace.
  It ensures proper combustion of fuel.
• Q16: Briefly explain the construction of Blast Furnace.
  Ans: A blast furnace is a tall steel structure lined with refractory material.
  It consists of throat, stack, bosh, and hearth.
  It also includes tuyeres, bustle pipe, and charging system.
• Q17: What is the composition of Charge in Blast Furnace?
  Ans: The charge consists of:

  • ➔ Iron ore
  • ➔ Coke
  • ➔ Limestone
• Q18: What is the quantity of Ore required to be fed in the Blast Furnace?
  Ans: The quantity of ore depends on the size and capacity of the furnace.
  Generally, it is fed in proper proportion with coke and limestone for efficient operation.
• Q19: What is Pig Iron?
  Ans: Pig iron is the crude form of iron obtained directly from a blast furnace.
  It contains high carbon content and impurities.
• Q20: State the properties of Pig Iron.
  Ans: The properties are:

  • ➔ High carbon content
  • ➔ Hard and brittle
  • ➔ Low melting point
  • ➔ Cannot be easily welded
  • ➔ Good fluidity when molten
• Q21: State the uses of Pig Iron.
  Ans: The uses are:

  • ➔ Making cast iron
  • ➔ Production of steel
  • ➔ Manufacturing of pipes and fittings
• Q22: State the types of Pig Iron.
  Ans: The types are:

  • ➔ White Pig Iron
  • ➔ Grey Pig Iron
  • ➔ Mottled Pig Iron
• Q23: What is White Pig Iron?
  Ans: White pig iron has carbon in the form of cementite.
  It is hard, brittle, and has a white fractured surface.
• Q24: What is Grey Pig Iron?
  Ans: Grey pig iron contains carbon in the form of graphite.
  It is softer and has a grey fractured surface.
• Q25: What is Molted Pig Iron?
  Ans: Molted (Mottled) pig iron has properties between white and grey pig iron.
  It contains both cementite and graphite.
• Q26: What is Wrought Iron?
  Ans: Wrought iron is a pure form of iron with very low carbon content.
  It is soft, ductile, and easily workable.
• Q27: State the uses of Wrought Iron.
  Ans: The uses are:

  • ➔ Chains and hooks
  • ➔ Pipes and tubes
  • ➔ Decorative items
  • ➔ Agricultural tools
• Q28: Briefly explain the charging procedure of Blast Furnace.
  Ans: Charging is the process of adding raw materials into the blast furnace.
  Iron ore, coke, and limestone are fed from the top through hoppers.
  Materials are added in layers for proper reaction.
• Q29: What is a Conveyor Belt?
  Ans: A conveyor belt is a machine used to transport materials from one place to another.
  It is commonly used to carry raw materials into the blast furnace.
• Q30: What is Coke?
  Ans: Coke is a fuel made by heating coal in the absence of air.
  It is rich in carbon and used in blast furnaces.
• Q31: What is the function of Coke in Blast Furnace?
  Ans: The functions are:

  • ➔ Acts as a fuel to produce heat
  • ➔ Produces carbon monoxide for reduction
  • ➔ Provides support to the charge
• Q32: State the Chemical Reactions in the Blast Furnace.
  Ans: The main chemical reactions in a blast furnace are:

  • ➔ C + O₂ → CO₂ (Combustion of coke)
  • ➔ CO₂ + C → 2CO (Formation of carbon monoxide)
  • ➔ Fe₂O₃ + 3CO → 2Fe + 3CO₂ (Reduction of iron ore)
• Q33: What is Direct Reduction?
  Ans: Direct reduction is the process in which iron oxide is reduced directly by solid carbon (coke).
  It occurs at higher temperature in the lower part of the furnace.
• Q34: What is Indirect Reduction?
  Ans: Indirect reduction is the process in which iron oxide is reduced by carbon monoxide (CO) gas.
  It is the main method of reduction in the upper zones of the blast furnace.
• Q35: State the zones of Blast Furnace.
  Ans: The zones are:

  • ➔ Reduction Zone
  • ➔ Heat Absorption Zone
  • ➔ Fusion Zone
  • ➔ Combustion Zone
• Q36: What is a Reduction Zone?
  Ans: The reduction zone is the upper part of the blast furnace.
  In this zone, iron ore is reduced into iron by carbon monoxide.
• Q37: What is a Heat Absorption Zone?
  Ans: The heat absorption zone is the region where materials absorb heat from rising gases.
  This prepares them for further reduction and melting.
• Q38: What is a Fusion Zone?
  Ans: The fusion zone is the part where iron starts melting.
  Slag is also formed in this zone.
• Q39: What is a Combustion Zone?
  Ans: The combustion zone is near the bottom of the furnace.
  Here coke burns in the presence of hot air to produce heat.
• Q40: Briefly explain the taping of Molten Iron.
  Ans: Tapping of molten iron is the process of removing liquid iron from the blast furnace.
  A tap hole is opened at the bottom, and molten iron flows into ladles.
• Q41: Briefly explain the taping of Slag.
  Ans: Slag is removed separately from the furnace through a slag hole.
  It floats above molten iron and is tapped out periodically.
• Q42: What is an Ancillary Plant?
  Ans: An ancillary plant is a supporting system of a blast furnace.
  It helps in supplying air, fuel, and raw materials efficiently.
• Q43: State the parts of an Ancillary Plant.
  Ans: The parts are:

  • ➔ Gas cleaning plant
  • ➔ Hot blast stoves
  • ➔ Turbo blowers
  • ➔ Stock house
• Q44: What are Refractory Bricks?
  Ans: Refractory bricks are special heat-resistant bricks used to line the furnace.
  They can withstand very high temperatures.
• Q45: Name the fuels used for Blast Furnace.
  Ans: The fuels are:

  • ➔ Coke
  • ➔ Coal
  • ➔ Natural gas (in some furnaces)
• Q46: What is Flux?
  Ans: Flux is a material added in the blast furnace to remove impurities from ore.
  It mainly reacts with impurities to form slag.
• Q47: State the properties of Flux.
  Ans: The properties are:

  • ➔ Easily reacts with impurities
  • ➔ Forms low melting slag
  • ➔ Reduces melting temperature
• Q48: What is the use of Flux?
  Ans: The use of flux is:

  • ➔ To remove impurities like silica
  • ➔ To form slag
  • ➔ To purify molten iron
• Q49: What is the highest temperature of the Reduction Zone of Blast Furnace?
  Ans: The highest temperature of the reduction zone is about 900^oC to 1200^oC.
• Q50: What is the highest temperature of the Absorption Zone of Blast Furnace?
  Ans: The highest temperature of the absorption zone is about 400^oC to 900^oC.