Chemistry · Science General

Metallurgical Processes

1,403 Questions

This section explores key metallurgical processes including ore concentration, pyrometallurgy, and metal refining. It also covers corrosion and the properties of refractory materials. These chemistry questions are relevant for engineering and science entrance tests.

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Metallurgical Processes Questions

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

The pyrometallurgical operations involve the use of:

  1. High temperature

  2. Sulphide ores

  3. Electrolysis

  4. Complexation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Pyrometallurgy employs high temperatures to carry out smelting and refining operations to extract metals from their minerals. 


Hydrometallurgy uses aqueous solutions to separate the desired metals. Finally, electrometallurgy employs electrical energy to extract and refine metals.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Hydro-metallurgical process of extraction of metals is based on :

  1. Complex formation

  2. Hydrolysis

  3. Dehydration

  4. Dehydrogenation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Hydrometallurgy is a technique involving the use of aqueous chemistry for the recovery of metals from ores, concentrates, and recycled or residual materials. This process is used in extraction of less electro positive or less reactive metals like gold and silver by complex formation. 

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

For the pyrometallurgical method used for the extraction of copper from sulphide ore, which statement(s) is/are correct?

  1. Pyrometallurgy is a dry method
  2. It involves concentration by leaching the sulphide ore with dil. $H _2SO _4$

  3. It involves concentration of the sulphide ore by froth flotation process

  4. It involves concentration by leaching for every ore
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation
The copper is extracted from sulphide ore by pyrometallurgy which involves reduction of the concentrated ore at high temperature.
This process is a dry process.
In this process, the sulphide ore is concentrated by froth floatation process.
In this process, the sulphide ore is not concentrated by leaching with dil sulphuric acid.
Thus, statements B  and D are incorrect and statement A and C are correct.
Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Copper can he extracted by hydrometallurgy but not zinc because:

  1. Copper is comparatively less active metal as its reduction potential is high. It can be displaced from solutions of $Cu^{2+}$ ion by more active metals.
  2. Zn displaced from solution of $Zn^{2+}$ ion, a more reactive metal than it, but then readily react with water forming their corresponding ions and evolve hydrogen gas.

  3. Both (A) and (B) are correct.

  4. Copper can never be extracted by hydrometallurgy.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Hydrometallurgy involves formation of aqueous complex compounds and is used in extraction of less electro positive or less reactive metals like gold and silver. 


  • Copper is  also comparatively less active metal as its reduction potential is high and it can be displaced from solutions of $Cu^{2+}$ ion by more active metals.

  • $Zn$ can also be displaced from solution of $Zn^{2+}$ ion by a more reactive metal than it, but then readily react with water forming their corresponding zinc ions and evolve hydrogen gas.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Metals which can be extracted by smelting process is/are:

  1. $Sn$
  2. $Cu$
  3. $Zn$
  4. $Al$
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

The process of extracting a metal from its oxide is known as 'smelting'. Most smelting processes involve direct reduction of the ore by carbon to metal and carbon dioxide. The production of primary aluminium is a good example of such a process.
Metals include copper, nickel, lead, zinc, silver, cobalt, gold, cadmium, etc.
Hence options A,B,C & D are correct.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Which of the following process involves smelting?

  1. ${2PbS+3O _2\rightarrow 2PbO+2SO _2}$
  2. ${Al _2O _3.2H _2O \rightarrow Al _2O _3+2H _2O}$
  3. ${Fe _2O _3+CO\rightarrow 2Fe+2CO _2}$
  4. ${Cr _2O _3+2Al\rightarrow Al _2O _3+2Cr+Heat}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Smelting : The process of extraction of metal in its molten state by any reducing agent in presence of flux is called smelting. 
For example : oxides of less electro - positive metals like Pb, Zn, Fe, Cu are reduced by any other reducing agents.
Reactions:
${Fe _2O _3+3CO\rightarrow  2Fe+3CO _2}$
Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

During the extraction of copper, the impurity (FeS) is removed as slag by mixing the contaminated copper ore with silica and coke. The molecular formula of slag is:

  1. $FeSiO _3$
  2. $Fe _2O _3$
  3. $FeSi\ (solid)$
  4. $FeSi\ (vapour)$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

During copper extraction, iron impurity (FeS) is removed by reacting it with silica (SiO2) to form iron silicate (FeSiO3), which is the slag.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Aluminum metal is frequently used as a reducing agent for the extraction of metal such as chromium or manganese from their respective _______

  1. zinc

  2. oxides

  3. reduction

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Aluminium is more electropositive than Cr or Mn.
Hence, aluminum metal is frequently used as reducing agent for the extraction of metal such as chromium or manganese from their respective oxides.
The process of reduction is known as Aluminothermy. Thermite mixture $Fe _2O _3 + Al$ in 3:1 ratio is used.
$Cr _2 O _3 + 2Al       \rightarrow      Al _2O _3 + 2Cr$
$3 Mn _3 O _4 + 8 Al    \rightarrow     4 Al _2 O _3 + 9 Mn$

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

The metallurgical process in which a metal is obtained in a fused state is called:

  1. Smelting

  2. Roasting

  3. Calcination

  4. Froth floatation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The process of extraction of metal in its molten state by any reducing agent in the presence of flux is called smelting. 

For example oxides of less electropositive metals like $Pb, Zn, Fe, Cu$ are reduced by any other reducing agents.

So, the correct option is $A$
Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry
Reduction to free metal: some of the methods commonly used to get free metal from the concentrates ore are below.
Smelting: The process of extracting a metal in the state of fusions is called smelting. In this process the ore is mixed with carbon and heated in suitable furnace
Electrolytic reduction process: This process is used in the extraction of the alkali and alkaline earth metals, zinc and aluminium.
Self reduction process: The sulphide ores of less electropositive metals like Hg, Pb, Cu etc., are heated in air so asto convert part of the ore into oxide or sulphate which then reacts with the remaining sulphide ore to give the metal.

After partial roasting, the sulphide of copper is reduced by :

  1. Reduction by carbon

  2. Electrolysis

  3. Self-reduction

  4. Cyanide process
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
In the extraction of copper, metal is formed in the Bessemer converter due to self reduction as

${ Cu } _{ 2 }S+2{ Cu } _{ 2 }O\rightarrow 6Cu+S{ O } _{ 2 }$
Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry
Reduction to free metal: some of the methods commonly used to get free metal from the concentrates ore are below.
Smelting: The process of extracting a metal in the state of fusions is called smelting. In this process, the ore is mixed with carbon and heated in a suitable furnace
Electrolytic reduction process: This process is used in the extraction of the alkali and alkaline earth metals, zinc and aluminium.
Self-reduction process: The sulphide ores of less electropositive metals like Hg, Pb, Cu etc., are heated in the air so as to convert part of the ore into oxide or sulphate which then reacts with the remaining sulphide ore to give the metal.

In the metallurgical extraction of zinc from ZnO, the reducing agent used is :
  1. $CO$
  2. $SO _{2}$
  3. $CO _{2}$
  4. $NO$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
In the metallurgical extraction of zinc from ZnO, the reducing agent used is C/CO.

$ZnO + C \rightarrow   Zn + CO$
$ ZnO + CO \rightarrow  Zn + CO _2$
Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

The smelting of iron in a blast furnace involves all the following processes except :

  1. combustion

  2. reduction

  3. slag formation

  4. sublimation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The smelting of iron in a blast furnace involves all the following processes except Sublimation.

Sublimation is the transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Which of the following methods is used in the concentration of haematite ore?

  1. Hydraulic washing

  2. Magnetic separation

  3. Froth floatation process

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Haematite (Fe2O3) is an oxide ore. Magnetic separation is the most effective method for concentrating haematite because it is magnetic, allowing it to be separated from non-magnetic gangue particles.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Which of the following is not an illustration of a smelting method?

  1. $2NaCl(fused)+electric \ energy\rightarrow 2Na+{Cl} _{2}$
  2. ${Al} _{2}{O} _{3}+3C \rightarrow 2Al+3CO$
  3. $2ZnS+3{O} _{2}\rightarrow 2ZnO+2{SO} _{2}$
  4. $CuO+{H} _{2}\rightarrow Cu+{H} _{2}O$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

It is the process by which a metal is obtained, either as the element or as a simple compound, from its ore by heating beyond the melting point, ordinarily in the presence of oxidizing agents, such as air, or reducing agents, such as coke. An oxidising agent is used in case of Al,Zn and Cu and so sodium reaction is not a smelting method.