This set of Iron Making Multiple Choice Questions & Answers (MCQs) focuses on “Gas Flow and Furnace Irregularities”.
1. Which of these remedies you are likely to adopt in case of a hanging blast furnace?
a) Charge more amount of coke
b) Reduce the hot blast pressure
c) Increase the hot blast pressure
d) Increase hot blast temperature
View Answer
Explanation: Hanging occurs when the uniform descend of the burden through the stack is hindered due to some reason. One of the most general remedies of hanging is to reduce the hot blast pressure. Reduction of hot blast pressure results in uniform distribution of the blast which helps the burden descend down. Usually a colder blast is preferred for a hanging burden.
2. What can be a probable reason for scaffolding in a blast furnace?
a) Presence of alkali oxides in the burden
b) Presence of acidic oxides in the burden
c) Presence of alkali chlorides in the burden
d) Presence of high melting phases in the burden
View Answer
Explanation: Scaffolding occurs due to the presence of alkali oxides in the burden. These alkali oxides form a low melting phase of alkali-alumina-silicates to which ore particles stick subsequently resulting in a huge block of mass.
3. Which of these irregularities is an aftermath of hanging or scaffolding?
a) Pillaring
b) Breakout
c) Slip
d) Choking
View Answer
Explanation: Slip occurs when the burden suddenly descends into the bosh region. Slip is an aftermath of scaffolding or hanging and can result in violent explosion. Controlling the blast pressure is a way to avoid slipping while handling irregularities like hanging and scaffolding.
4. How would you like to describe pillaring in a blast furnace?
a) Formation of a cold central column in the stock
b) Formation of big lumps inside the blast furnace
c) Flying off of the burden due to high blast pressure
d) Choking of the stock
View Answer
Explanation: Pillaring is the formation of a cold central column in the stock. This occurs when the hot blast does not penetrate to the center of the stock rather passes through the vicinity of the wall.
5. Which of these precautionary measures that can be taken to prevent breakout?
a) Hearth refractory with many joints.
b) Using steel shell for hearth instead of cast iron shell
c) Hearth refractory with minimum joints and adopting carbon hearth
d) Increasing hot metal temperature
View Answer
Explanation: Breakout occurs when the wall of the hearth is broken and the hot metal and slag flows out. This can be prevented by using minimum number of refractory joints and adopting corrosion resistant carbon refractories. Increasing the hot metal temperature will speed up corrosion making the hearth more prone to breakouts.
6. How can channeling in a blast furnace be avoided?
a) Using fines as charge material
b) Having a good permeability of the bed through uniform burden distribution
c) Using lump ores for high bed permeability
d) Having a high blast pressure
View Answer
Explanation: Channeling can be avoided by have a uniform burden distribution and having a good bed permeability. Having a high blast pressure though a feasible method is not preferred because it can result in flooding of the BF and consumes extra energy.
7. What happens in a salamander formation in the hearth?
a) The hearth capacity is reduced
b) The hot metal leaks out of the hearth
c) The hearth capacity is increased due to corrosion
d) The hearth metal solidifies
View Answer
Explanation: In a salamander formation in the hearth, the hot metal over time corrodes the lining and penetrates the bottom of the hearth forming a pool of hot metal which cannot be tapped. The hearth capacity is increased but the tap volume decreases.
Sanfoundry Global Education & Learning Series – Iron Making.
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