Tag: metallurgy

Questions Related to metallurgy

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 :
thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. $CO$

  2. $SO _{2}$

  3. $CO _{2}$

  4. $NO$

Show answer
Correct Option: A
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$

Which of the following reaction represents the action of steam on heated iron?

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

  1. $3Fe+4H _2O\rightarrow Fe _3O _4+4H _2$

  2. $2Fe+3H _2O\rightarrow Fe _2O _3+3H _2$

  3. $Fe+H _2O\rightarrow FeO+H _2$

  4. $2Fe+H _2O+O _2\rightarrow Fe _2O _3+H _2$

Show answer
Correct Option: A
Explanation:
When steam is passed over a red hot iron to form the ferric oxide and hydrogen gas is released.

The action of steam on heated iron is represented as follows:

$3Fe+4H _2O\rightarrow Fe _3O _4+4H _2$

Hence, option A is the correct answer.

Which of the following is purest form of iron?

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

  1. Wrought iron

  2. Pig iron

  3. Steel

  4. None of these

Show answer
Correct Option: A
Explanation:

Wrought iron is purest form of iron.

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

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

  1. combustion

  2. reduction

  3. slag formation

  4. sublimation

Show answer
Correct Option: D
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.

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

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

  1. Hydraulic washing

  2. Magnetic separation

  3. Froth floatation process

  4. None of these

Show answer
Correct Option: B

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

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

  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. $CuO+{H} _{2}\rightarrow Cu+{H} _{2}O$

Show answer
Correct Option: A
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.

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 :
thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. $Fe$

  2. $Pb$

  3. $Na$

  4. $Cu$

Show answer
Correct Option: C
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:
$Na^+ + e^- \rightarrow Na$

(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?

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

  1. a, b and c

  2. b and c

  3. only a

  4. only d

Show answer
Correct Option: A
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.

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

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

  1. oxidation

  2. reduction

  3. fractional distillation

  4. electrolysis

  5. None of the above

Show answer
Correct Option: B

Nitriding is a process of heating steel in atmosphere of:

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

  1. $NH _3$

  2. $N _2$

  3. $O _2$

  4. $CO _2$

Show answer
Correct Option: A
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.