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

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

Which one is mismatched ?

  1. Poling - refining of copper

  2. Cupellation - refining of silver

  3. Smelting - An oxidation process

  4. Roasting - An oxidation process
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Poling: The molten impure metal (Cu) containing oxides as impurities is stirred with green poles of wood which releases hydrocarbon gases. The hydrocarbon gases reduces oxide to metal. It is used in refining of copper.

Cupellation: Pb present in Ag is removed by this method. The impure metal is heated in a cupel or oval shaped crucible made of bone ash or cement and blast of air is passed over the molten mass. The impurities get oxidised and removed with the blast of air. It is used in refining of silver.

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 electropositive metals like Pb, Zn, Fe, Cu are reduced by any other reducing agents. Thus, smelting is a reduction process and not an oxidation process.

Roasting: The process in which the concentrated ore is heated in blast of air and ore gets converted into oxide and impurities like sulphur, arsenic are also oxidised to their oxides and is removed is called Roasting. It requires very high temperature and specialized furnace like Bessemer or reverberatory furnace. Thus, it is an ixidation process.



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.

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.