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 chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

Roasting of copper pyrites is done:

  1. to remove moisture and volatile impurities

  2. to oxidise free sulphur
  3. to decompose pyrites into ${Cu} _{2}S$ and $FeS$
  4. to decompose ${Cu} _{2}S$ into blister copper
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

During roasting of copper pyrite ore: 

(A) moisture is removed and sulphur, arsenic and antimony are removed in the form of their volatile oxides.
(B) Free sulphur is oxidized to sulphur dioxide.
(C) Coppr pyrite decomposes into cuprous sulphide and ferrous sulphide.

Thus options A, B and C are correct.
(D) Cuprous sulphide is decomposed into blister copper during bessemerisation. 
Thus option D is incorrect.

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

Name the process  used for the formation of blister $Cu$ by following reaction :(unbalanced reactions)

$2Cu _2S\, +\, 3O _2\, \rightarrow\, Cu _2O\, +\, SO _2$

$Cu _2O\, +\, Cu _2S\, \rightarrow\, Cu\, +\, SO _2$ 

  1. Bessemerisation

  2. Parkes or Pattinson process

  3. Forth flotation

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

The process is called bessemerisation.  $Cu$ produced by Bessemerisation is known as blister $Cu$ which is $95 $%  pure. The balanced chemical reactions are as shown.

$2Cu _2S\, +\, 3O _2\, \rightarrow\, 2Cu _2O\, +\, 2SO _2$

$2Cu _2O\, +\, Cu _2S\, \rightarrow\, 6Cu\, +\, SO _2$

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

In the extraction of Cu, the reaction takes place in bessemer converter is:

  1. $2Cu _2O\, +\, Cu _2S\, \rightarrow\, 6Cu\, +\, SO _2$
  2. $2CuFeS _2\, +\, O _2\, \rightarrow\, Cu _2S\, +\, FeS\, +\, SO _2$
  3. $2Cu _2S\, +\, 3O _2\, \rightarrow\, 2Cu _2O\, +\,2SO _2$
  4. $2FeS\, +\, 3O _2\, \rightarrow\, 2FeO\, +\, 2SO _2$
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

The sulphide ore of copper is heated in the air until a part is converted to oxide and then further heating in the absence of air to let the oxide react with unchanged sulphide.


Self-reduction of CuS to Cu can be carried out in either Bessemer converter or Pierce-Smith converter.

$2Cu _2S+3O _2 \rightarrow 2Cu _2O + 2SO _2$
$2Cu _2O+Cu _2S \rightarrow 6Cu+SO _2$

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

The final step for the extraction of copper pyrites in Bessemer converter involves the reaction__________.

  1. $Cu _2S\,+\,2FeO\,\rightarrow\,2Cu\,+\,2Fe\,+\,SO _2$
  2. $Cu _2S\,+\,2Cu _2O\,\rightarrow\,6Cu\,+\,SO _2$
  3. $4Cu _2O\,+\,FeS\,\rightarrow\,8Cu\,+\,2FeSO _4$
  4. $2Cu _2O\,+\,FeS\,\rightarrow\,4Cu\,+\,Fe\,+\,SO _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The sulphide ore of copper is heated in air until a part is converted to oxide and then further heating in the absence of air to let the oxide react with unchanged sulphide.
Self-reduction of CuS to Cu can be carried out in either Bessemer converter or Pierce-Smith converter.
$2Cu _2S+3O-2 \rightarrow 2Cu _2O + 2SO _2$
$2Cu _2O+Cu _2S \rightarrow 6Cu+SO _2$
This is the final step in Bessemer converter.

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

Self-reduction of CuS to Cu can be carried out in :

  1. Bessemer converter

  2. Blast furnace

  3. Both (A) and (B)

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

The following reaction takes place in Bessemer converter :


$ Cu _2S + \dfrac{3}{2}O _2 \rightarrow Cu _2O + SO _2$

$2Cu _2O + Cu _2S \longrightarrow 6Cu + SO _2$

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

Which of the following statement is correct regarding Cu-extraction ?

  1. In the smelting step, carbon reduction takes places
  2. During roasting, $Cu _2S$ remains almost unaffected

  3. In Bessemer converter, only self reduction occurs, not slag formation
  4. Blister formed in the blister Cu is due to dissolved $CO _2$
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

${ Cu } _{ 2 }S+2{ Cu } _{ 2 }O\rightarrow 6Cu+S{ O } _{ 2 }$
So Option C is correct
Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

Extraction of zinc from zinc blende is achieved by:

  1. electrolytic reduction

  2. roasting followed by reduction with carbon

  3. roasting followed by reduction with another metal

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

Zinc blende (ZnS) is first roasted to form zinc oxide (ZnO), which is then reduced to zinc metal using carbon (coke).

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

In the extraction of copper, metal is formed in the Bessemer converter due to a reaction:-

  1. ${Cu _2S+2Cu _2O\rightarrow 6Cu+SO _2}$
  2. ${Cu _2S\rightarrow 2Cu+S}$
  3. ${Fe+Cu _2O\rightarrow 2Cu+FeO}$
  4. ${2Cu _2O\rightarrow 4Cu+O _2}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
In the extraction of copper, metal is formed in the Bessemer converter due to self reduction.

Reaction:
$Cu _2S + 2Cu _2O \longrightarrow 6Cu + SO _2$
Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy
The slag obtained during the extraction of copper pyrites is composed mainly of ${ FeSiO } _{ 3 }$.

  1. True

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

Copper is mainly extracted from copper pyrites. After the concentration of its ore by froth flotation process, the ore is roasted in a current of air to remove arsenic, antimony and much of sulphur.

The ore is then mixed with a little coke and sand and smelted in a water-jacketed blast furnace. The minor reactions that occured during roasting continue here. Ferrous oxide combines with sand to form a fusible slag.

$FeO + SiO _2 \rightarrow FeSiO _3$ slag

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

Copper is extracted from the ore copper pyrite by smelting in a blast furnace. The flux used and the slag formed are :

  1. flux $CaO$, slag $CaSiO _3$
  2. flux $SiO _2$, slag $CaSiO _3$
  3. flux $FeO$, slag $FeSiO _3$
  4. flux $SiO _2$,slag $FeSiO _3$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Copper is extracted from the ore copper pyrite by smelting in a blast furnace. The flux used is  $SiO _2$ and slag formed is $FeSiO _3$.

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

Polling process is employed for the removal of:

  1. $Cu _2O\ from \ Cu$
  2. $Al _2O _3\ from\ Al$
  3. $Fe _2O _3\ from\ Fe$

  4. None of the above.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Polling is a metallurgical method employed in the purification of copper which contains cuprous oxide as an impurity. 

In the past, freshly cut trees were used as wooden poles. The sap in these poles acted as the reducing agent. The heat of the copper makes the pole emit a gas that reduces the cuprous oxide to copper.