This set of Extractive Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Unit Processes for Metal Extraction”.
1. Extraction of iron in a blast furnace is carried out using which type of chemical process?
a) Oxidation of sulphide ores
b) Carbothermic reduction of oxide ores
c) Reduction of sulphide ores
d) Oxidation of oxides
View Answer
Explanation: Carbon is an important reducing agent because it is easily available and is not very expensive. We know that almost all metal oxides can be reduced by carbon provided it is done at high temperature. So, in a blast furnace, we use Carbothermic reduction of oxide ores.
2. What is the purpose of adding the limestone in a blast furnace?
a) It serves as a flux
b) To increase the temperature of the blast furnace
c) To reduce oxides
d) It acts as an oxidizing agent
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Explanation: Limestone with chemical formula CaCO3 serves as a flux in the blast furnace. The decomposed CaO combines with the gangue material to produce slag.
3. Complete the following reaction which occurs in a blast furnace.
Fe3O4(s) + CO (g) = ______ + CO2 (g) [The reaction is not balanced]
a) Fe2O3
b) O2
c) C
d) FeO
View Answer
Explanation: The above given reaction is a reduction reaction. This reaction occurs in the stack zone of the blast furnace. The completely balanced reaction is: Fe3O4(s) + CO (g) = ______ 3FeO (s) + CO2 (g).
4. Where is the liquid iron collected in the blast furnace?
a) Stack
b) Bosh
c) Hearth
d) Tuyeres
View Answer
Explanation: FeO is reduced in the lower regions of the blast furnace. The liquid product is collected in the bottom-most part of the blast furnace which is known as the hearth.
5. Which part of the blast furnace has the maximum temperature?
a) Topmost
b) Middle
c) Preheating zone
d) Lowermost
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Explanation: The blast furnace can be divided into three parts which are top, middle and lower zones. The blast furnace has the maximum temperature at the lowermost zone which can reach a temperature of about 1800°C. It reaches the maximum temperature because it is a direct reduction zone.
6. All the reaction which occur in the lower region of the blast furnace is exothermic.
a) True
b) False
View Answer
Explanation: The statement is incorrect. The lowermost zone of the blast furnace is a direct reduction zone. All the reactions that take place are reduction reactions and are endothermic.
7. Which metal is used for the reduction of Fe2O3 which is used in the Thermit welding process?
a) Boron
b) Calcium
c) Sulphur
d) Aluminium
View Answer
Explanation: Aluminium is the metal used for the reduction of Fe2O3. This is the basis of a highly exothermic reaction which is used in the Thermit welding process.
8. Complete the following metallothermic reduction reaction.
Cr2O3(s) + Al(s) = _____ + Al2O3 (l) [The reaction is not balanced]
a) Cr
b) CrO
c) CrO3
d) Cr2O
View Answer
Explanation: A metallothermic reduction process is the one in which a compound is reduced using a metal like aluminium and silicon as reducing agents. The above reaction reduces Cr2O3 to Cr which is obtained in a liquid state. The completely balanced reaction is: Cr2O3(s) + 2Al(s) = 2Cr (l) + Al2O3 (l).
Sanfoundry Global Education & Learning Series – Extractive Metallurgy.
To practice all areas of Extractive Metallurgy, here is complete set of Multiple Choice Questions and Answers.
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