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.

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
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.

The metal extracted by electrolysis of its fused salt is :
  1. $Fe$
  2. $Pb$
  3. $Na$
  4. $Cu$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Na can not be obtained by electrolysis of the aqueous solution of salt as hydrogen ions have higher reduction potential than $Na^+$ so hydrogen ions will reduce first and we will get hydrogen gas instead of Na metal by electrolysis of the aqueous solution,

So sodium metal is extracted by electrolysis of its fused salt.

$NaCl \rightarrow Na^+ + Cl^-$


At cathode:
$Na^+ + e^- \rightarrow Na$

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

(a) In smelting process carried out in blast furnace for the exgtraction of iron, lower region of the furnace has the highest temperature.
(b) Formation of $CO$ from ${CO} _{2}$ and coke reduces the temperature of the middle region of blase furnace.
(c) Limestone is taken blast furnace as flux.
(d) Silica present in the ore as gangue is converted to fusible slag by the process of reduction
Which of the following regarding the process of smelting is correct?

  1. a, b and c

  2. b and c

  3. only a

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

The extraction of metal in the fused state is termed smelting. The ore is reduced by carbon to the free metal. A hot blast of air (sometimes with oxygen enrichment) is blown into the lower section of the furnace through a series of pipes . Formation of $CO$ from $CO _2$ and coke reduces the temperature of the middle region of blase furnace. Flux is a chemical substance which combines with gangue at higher temperaturesto form easily fusible material called slag which is not soluble in the molten metal. Limestone is taken blast furnace as basic flux. Silica present in the ore as gangue is converted to fusible slag by the process of oxidation  in flux.

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

The manufacture of iron from iron ore involves the process of :

  1. oxidation

  2. reduction

  3. fractional distillation

  4. electrolysis

  5. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The manufacture of iron from iron ore (like haematite) involves the reduction of iron oxide using a reducing agent such as carbon monoxide in a blast furnace.

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

Nitriding is a process of heating steel in atmosphere of:

  1. $NH _3$
  2. $N _2$
  3. $O _2$
  4. $CO _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Nitriding is the surface hardening process where nitrogen is added to the surface of steel parts using dissociated ammonia as the source. Gas nitriding develops a very hard case in a component at relatively low temperature. It is carried out at temperature below the transformation temperature of alloy steels and parts to be nitrided are heat treated to proper strength level and finally machined.

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

(a) Thermite welding process exploits the difference in reactivity of different metals.
(b) Zinc spelter is used as cathode in electrolyte refining process of zinc.
(c) Iron is generally refined by electrolytic reduction process
(d) Iron is alloyed with other metals and carbon, only to prevent corrosion.
Which of the following options regarding the above statements is correct?

  1. a and d

  2. b and c

  3. only a

  4. a, b and c
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Thermite welding process exploits the difference in reactivity of different metals. Pure zinc rod is used as cathode while a block of impure zinc spelter is used as anode. Iron is generally refined by smelting process.Iron is alloyed with other metals and carbon prevents the oxidation of iron and formation of rust.

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

Which of the following processes involves the smelting process?

  1. $ZnCO _3 \rightarrow ZnO + CO _2$
  2. $2PbS +3O _2 \rightarrow 2PbO + 2SO _2$
  3. $Fe _2O _3 + 3C \rightarrow 2Fe + 3CO$
  4. $Al _2O _3.2H _2O \rightarrow Al _2O _3 + 2H _2O$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In smelting, Iron ore is reduced to iron.

$Fe _{2}O _{3}+3C{\rightarrow}Fe+3CO$

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

Which of the following methods is not involved in metallurgy of iron?

  1. Calcination

  2. Smelting

  3. Concentration of ore

  4. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
(1) Calcination is the process in which the ore is heated below its melting point, either in the absence or in a limited supply of air, in an aim to drive off volatile expunges, moisture, water of hydrates and organic matter from the ore. All ores are minerals but all minerals are not ores.

(2)Smelting is a process when a metal which is more reactive than copper needs to be extracted. For example, zinc is more reactive than copper so it has to be extracted by smelting.

(3)Ores are solid material from which a pure metal can be obtained. The process of removal of unwanted material from the ore is known as concentration or dressing or benefaction of ores.

So Calcination, Smelting, Concentration of ore all the processes used in metallurgy.
Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Iron is used in different forms, like, cast iron, steel, and alloys. The iron-carbon diagram is the basis for the branch of science known as:

  1. ferrous metallurgy

  2. stereochemistry

  3. carbon metallurgy

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

The percentage of Iron and Carbon determine whether it is cast Iron, Pig Iron, Steel or Alloys. Hence this is known as Ferrous Metallurgy. The main contribution is given by Iron as every type of Iron contains more than 90% of Iron.

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

In which of the following pair(s), the minerals are converted in to metals by self-reduction process?

  1. $Cu _2S, PbS$
  2. $PbS, HgS$
  3. $PbS, ZnS$
  4. $Ag _2S, Cu _2S$
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

In the self reduction process, metal sulfide reacts with metal oxide to form free metal.
The conversion of metal ore to crude metal by self reduction process is carried for the pairs $Cu _2S, PbS$ and $PbS, HgS$.
For example cupric oxide reacts with cupric sulphide to form crude copper metal.
$2PbS+3O _2\rightarrow 2PbO+2SO _2$
$PbS+2PbO\rightarrow 3Pb+SO _2$ (self reduction)
$Cu _2S+2Cu _2O\rightarrow 6Cu+SO _2$
$HgS+2HgO\rightarrow 3Hg+SO _2$ 

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

Which of the following steps are involved in hydrometallurgical process?

  1. $Cu _2S + 2Cu _2O \longrightarrow 6Cu + SO _2$
  2. $CuFeS _2 + 2H _2SO _4 \longrightarrow CuSO _4 + FeSO _4 + 2H _2S$
  3. $Ag _2S + 2NaCN \longrightarrow [Ag(CN) _2]^- + Na _2S$
  4. $CuCO _3 + H _2SO _4 \longrightarrow CuSO _4 + H _2O +CO _2$
Reveal answer Fill a bubble to check yourself
B,C,D Correct answer
Explanation

Hydro metallurgy is a process of extraction of metals by converting their ores into aqueous solutions of metal compounds and reduction of these solutions using suitable reducing agents.Less electropositive metals like gold and silver are extracted by this method . 
Water, dilute acids or sodium cyanide solution are used to convert the metal present in the ore into solution.
Hence, the following steps are involved in hydrometallurgical process.
(B) $CuFeS _2 + 2H _2SO _4 \longrightarrow CuSO _4 + FeSO _4 + 2H _2S$
(C) $Ag _2S + 2NaCN \longrightarrow [Ag(CN) _2]^- + Na _2S$
(D) $CuCO _3 + H _2SO _4 \longrightarrow CuSO _4 + H _2O +CO _2$

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

Formation of metallic copper from the sulphide ore in the normal thermo-metallurgical process essentially involves which one of the following reaction? 

  1. $\displaystyle CuS+\frac { 3 }{ 2 } { O } _{ 2 }\longrightarrow CuO+{ SO } _{ 2 };\quad CuO+C\longrightarrow Cu+CO$
  2. $\displaystyle CuS+\frac { 3 }{ 2 } { O } _{ 2 }\longrightarrow CuO+{ SO } _{ 2 };\quad 2CuO+CuS\longrightarrow 3Cu+{ SO } _{ 2 }$
  3. $\displaystyle CuS+{ 2O } _{ 2 }\longrightarrow { CuSO } _{ 4 };\quad { CuSO } _{ 4 }+CuS\longrightarrow 2Cu+{ 2SO } _{ 2 }$
  4. $\displaystyle CuS+\frac { 3 }{ 2 } { O } _{ 2 }\longrightarrow CuO+{ SO } _{ 2 };\quad CuO+CO\longrightarrow Cu+{ CO } _{ 2 }$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Thermo-metallurgical process:

Here first sulphide ore coverts into oxide and then self reduction occurs as:
$\displaystyle CuS+\frac { 3 }{ 2 } { O } _{ 2 }\longrightarrow CuO+{ SO } _{ 2 }$
$\ 2CuO+CuS\longrightarrow 3Cu+{ SO } _{ 2 }$

Multiple choice

What is the purpose of annealing in metalworking?

  1. To increase hardness

  2. To increase strength

  3. To relieve internal stresses

  4. To improve corrosion resistance
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Annealing is a heat treatment process used to relieve internal stresses and improve the ductility of metals.

Multiple choice

What is the name of the process by which a metal loses electrons?

  1. Oxidation

  2. Reduction

  3. Corrosion

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

Oxidation is the process by which a metal loses electrons, resulting in an increase in its oxidation state.