Chemistry · Science General

Metallurgical Processes

1,436 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.

Pyrometallurgy furnacesMetal refining techniquesCorrosion protection methodsOre concentrationAuto reduction process

Metallurgical Processes Questions

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

The disadvantage of carbon reduction method are :

  1. high temperature needed which is expensive and requires the use of a blast furnace

  2. many metals combine with carbon forming carbides
  3. carbon combines with oxygen to form poisonous $CO$

  4. carbon cannot be used with highly electropositive metals
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

 The disadvantage of carbon reduction method are
(i) high temperature needed which is expensive and requires the use of a blast furnace
(ii) many metals combine with carbon forming carbides
(iii) carbon dioxide gas is released in the process which is green house gas.
(iii) metals produced contain significant amount of carbon. hence, metals obtained cannot be very pure.

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

Pyrometallurgical method used for the extraction of copper from sulphide ore:

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

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

  4. statement given in (b) is incorrect
Reveal answer Fill a bubble to check yourself
D 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, the statement B is incorrect and the statement A and C are correct.

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

Write chemical equations for metallurgical processes to represent the reduction of $Cu _2O$ using charcoal as a reducing agent :

  1. $2Cu _2O\, +\, C\, \overset{\Delta}{\rightarrow}\, 4Cu\, +\, CO _2$
  2. $Cu _2O\, +\, C\, \overset{\Delta}{\rightarrow}\, 2Cu\, +\, CO$
  3. $3Cu _2O\, +\, 2C\, \overset{\Delta}{\rightarrow}\, 6Cu\, +\, CO +\, CO _2$

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

Chemical equations for reduction of $Cu _2O$ using charcoal as a reducing agent : 

$Cu _2O\, +\, C\, \overset{\Delta}{\rightarrow}\, 2Cu\, +\, CO$.

This process is carbon reduction.


Hence option B is correct.

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

Chemical reactions of the hydrometallurgical extraction of copper is/are?

  1. $CuO\, +\, H _2SO _4\, \rightarrow\, CuSO _4\, +\, H _2O$
  2. $CuCO _3\, +\, H _2SO _4\, \rightarrow\, CuSO _4\, +\, H _2O\, +\, CO _2$
  3. $Cu _2S\, +\, 2H _2SO _4\, +\, 2O _2\, \rightarrow\, 2CuSO _4\, +\, SO _2\, +\, 2H _2O$

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Hydrometallurgical extraction of copper involves leaching copper ores with sulfuric acid to produce copper sulfate solution, which is then processed to recover copper. All the listed reactions represent valid leaching processes for different copper ores.

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

$AgCl$ (horn silver) is converted into $Ag$ by the pyrometallurgical method.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Pyrometallurgy is the process of extraction and purification involving the application of heat.

By this process chloride residues are smelted with an agent such as sodium silicate that provides alkali  metal oxide without generating gases, such as $CO _2$.
$2AgCl+Na _2O+SiO _2\longrightarrow Ag _2O+2NaCl+SiO _2$
$Ag _2O\longrightarrow 2Ag+\cfrac {1}{2}O _2$.

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

When $FeCr _2O _4$ is heated with carbon an alloy called ferrochrome is obtained.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ferrochrome is produced by reduction of  $Cr-ore$ (an oxide of Chromium and iron) with coal and coke.

Ferrochrome is iron-chromium alloy. So, the statement "when $FeCr _2O _4$ is heated with carbon an alloy Ferrochrome is obtained" is correct.

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

In iron metallurgy, lime stone is used :

  1. To obtain heat energy

  2. To reduce iron oxide into iron

  3. As an iron ore
  4. To remove sand ($SiO _2$)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In the extraction of iron, the roasted ore is mixed with coke and lime stone (flux) and is then heated in the presence of air at high temperature in a furnace. Impurity of $SiO _2 $ is removed as calcium silicate $(CaSiO _3 slag)$.
$ CaCO _3\rightarrow CaO+CO _2$
$CaO+SiO _2\rightarrow CaSiO _3$

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

During smelting, an additional substance is added which combines with impurities to form a fusible product. It is known as :

  1. Slag

  2. Mud

  3. Gangue

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

Flux is a substance which may be either acidic oxide $(Si{O} _{2})$ or basic oxide $(CaO, MgO)$. It combines with certain impurities (gangue particles) in order to form a substance called slag. This can be easily removed.

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.