This set of Extractive Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Calcination and Roasting”.
1. In which pyrometallurgical process do we do the thermal treatment of ores to eliminate volatile products like carbon dioxide and water?
a) Roasting
b) Calcination
c) Smelting
d) Degassing
View Answer
Explanation: Calcination is a Pyrometallurgical process. It decomposes an ore after thermal treating it to eliminate volatile products like carbon dioxide and water. Calcination requires a high temperature which can be calculated using the free energy-temperature relationship.
2. Which metallurgical process is indicated by the following reaction?
ZnCO3 + Δ → ZnO + CO2↑
a) Calcination
b) Roasting
c) Leaching
d) Smelting
View Answer
Explanation: The above-shown reaction is a calcination process. The reaction shows the decomposition of zinc carbonate to zinc oxide and carbon dioxide after it was thermally treated. The above shown reaction is an endothermic reaction.
3. In the roasting process, we heat an ore above its melting point in the presence of excess air.
a) True
b) False
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Explanation: In the roasting process, we heat an ore or a concentrate below its melting point in the presence of excess air. This is because we do not want the ore to melt in the roasting process. We have to just make some chemical changes in the ore to make it ready for smelting.
4. What is the main objective of roasting?
a) To decompose an ore
b) To eliminate the main constituent of ore
c) Chemical conversion of an ore
d) Eliminate CO2
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Explanation: We must be aware that for leaching to be easier, we need metals to be present as sulphate or chloride or oxide. So, before proceeding to leach or smelting, we must change the chemical form of the mineral constituents of the ore by the roasting process.
5. Which one of the following is a type of roasting?
a) Sulphidizing
b) Sintering
c) Agglomeration
d) Volatilizing
View Answer
Explanation: There are three most important roasting operation-Oxidizing, Volatilizing and Chloridizing. Sulphidizing is not a roasting process. Sintering is an agglomeration process.
6. Which roasting operation shown below burns out Sulphur from a sulphide ore?
a) Oxidizing
b) Volatilizing
c) Chloridizing
d) Smelting
View Answer
Explanation: The most important roasting process is Oxidizing roasting. It eliminates Sulphur from sulphide ores and replaces it with oxide. Oxidizing roasting is done to replace or remove the impure element in the ore with oxygen.
7. During a roasting process, when the entire Sulphur is eliminated from the sulphide ore, the residue left afterwards is known as ______
a) catalyst
b) gangue
c) dead roast
d) oxidizer
View Answer
Explanation: During roasting, when the sulphide ore is completely oxidized then the process is known as dead roasting. The residue which is left over after dead roasting is known as dead roast.
8. What type of agent can speed up a roasting process?
a) Volatile oxide
b) Catalyst
c) Electrolyte
d) Roaster
View Answer
Explanation: Catalyst is a substance or an agent which increases the rate of a reaction. It is non-consumable. During the roasting process, Quartz is one of the catalysts which can be used.
9. Volatilizing roasting is a type of roasting done to eliminate volatile oxides in the presence of excess oxygen.
a) True
b) False
View Answer
Explanation: Volatilizing roasting is a process to eliminate volatile oxides like As2O3, Sb2O3 etc. from the ore in a very controlled supply of oxygen because an excess of oxygen may lead to non-volatile oxides.
10. Type of roasting processed on metal compounds to convert it into chlorides is called as _____
a) chloridizing roasting
b) volatilizing roasting
c) oxidizing roasting
d) sulphating roasting
View Answer
Explanation: Chloridizing Roasting is done to convert metal compounds into its chlorides. From these chlorides, we can obtain metals like uranium, zirconium, titanium etc. by reduction.
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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