Tag: basics of metallurgy

Questions Related to 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. $2FeS\, +\, 3O _2\, \rightarrow\, 2FeO\, +\, 2SO _2$


Correct Option: A,C
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.

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

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. $2Cu _2O\,+\,FeS\,\rightarrow\,4Cu\,+\,Fe\,+\,SO _2$


Correct Option: B
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.

Copper matte contains:

  1. $Cu _2S, Cu _2O$ and silica

  2. $Cu _2S, CuO$ and silica

  3. $Cu _2S, FeO$ and silica

  4. $Cu _2S, FeS$ and silica


Correct Option: D
Explanation:

Copper matte contains Copper Sulphide $Cu _2S$, iron sulphide $(FeS)$ with some amount of silica.


So, option D is correct.

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


Correct Option: A
Explanation:

The following reaction takes place in Bessemer converter :


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

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

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 $CO _2$


Correct Option: C
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

Auto reduction process is used  in the extraction of :

  1. Cu and Pb

  2. Zn and Hg

  3. Cu and AI

  4. Fe and Pb


Correct Option: A
Explanation:

Auto reduction process is used in the preparation of Cu, Hg and pb etc.

Which are less electro positive metal.

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


Correct Option: B

The composition of malachite is:

  1. $CuFeS _2$

  2. $CuCO _3$

  3. $CuCO _3.Cu(OH) _2$

  4. $Cu(OH) _2$


Correct Option: C
Explanation:

The chemical formula of malachite is $Cu _2CO _3(OH) _2$. Hence the composition is $CuCO _3.Cu(OH) _2$.

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. ${2Cu _2O\rightarrow 4Cu+O _2}$


Correct Option: A
Explanation:
In the extraction of copper, metal is formed in the Bessemer converter due to self reduction.

Reaction:
$Cu _2S + 2Cu _2O \longrightarrow 6Cu + SO _2$
The slag obtained during the extraction of copper pyrites is composed mainly of ${ FeSiO } _{ 3 }$.
  1. True

  2. False


Correct Option: A
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