Tag: basics of metallurgy

Questions Related to basics of metallurgy

STATEMENT-1: Extraction of zinc from sphalerite ore involves the roasting followed by reduction with coke.
STATEMENT-2 : Zinc can be commercially extracted by hydrometallurgy.

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

  1. STATEMENT-1 is True, STATEMENT-2 is True; STATEMENT-2 is a correct explanation for STATEMENT-1

  2. STATEMENT-1 is True, STATEMENT-2 is True; STATEMENT-2 is NOT a correct explanation for STATEMENT-1

  3. STATEMENT-1 is True, STATEMENT-2 is False

  4. STATEMENT-1 is False, STATEMENT-2 is True

Show answer
Correct Option: C
Explanation:

Sphalerite ((Zn,Fe)S) is a chief ore of zinc. It consists largely of zinc sulfide in crystalline form but almost always contains variable iron.
Extraction of Zinc follows:
Roasting followed by reduction with carbon; then electro-fining of Zn.

Hydrometallurgy:
In this process, desired metal is extracted from its solution by addition of more electro positive metal.
But there are very few metals which are more electro positive than Zn so it can not be extracted by hydrometallurgy

Which of the following process(s) occur(s) during the extraction of copper from chalcopyrites?

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

  1. froth floatation

  2. roasting

  3. bessemerisation

  4. leaching

Show answer
Correct Option: A,B,C
Explanation:

In the extraction of copper, following methods are used
froth floatation
roasting
smelting
bessemerisation and 
electrolytic refining

$Zn + NH _3 \quad\xrightarrow{\small{heat}} \quad ?$

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

  1. $ZnH _2 + N _2$

  2. $Zn _3N _2 + H _2$

  3. $Zn(NH _2) _2 + H _2$

  4. $[Zn(NH _3) _4]^{2+}$

Show answer
Correct Option: D
Explanation:

Zinc(II) ion forms complex ions readily.
Reaction of the process:
$Zn + xNH _3 \quad\xrightarrow{\small{red heat}} \quad Zn(NH _3) _x$
Where $x = 4$ to $6 $ 

The $Cu _{2}O$ impurity present in blister copper is removed by:

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

  1. liquation

  2. distillation

  3. poling

  4. zone refining

Show answer
Correct Option: C
Explanation:

Blister copper is refined by poling process where it removes impurity in form of $SO _2$ and $As _2O _3$.

Which of the metal can be obtained directly during the roasting of its sulphide ore?

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

  1. Cu

  2. Zn

  3. Fe

  4. Ca

Show answer
Correct Option: A
Explanation:

During the roasting of sulphide ore of Cu, $Cu _2O$ and $Cu _2S$ formed where they react with each other to produce Cu metal.

In the extraction of copper, the smelt formed in the blast furnace contains:

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

  1. $Cu _{2}S\ +$ little $FeS$

  2. $Cu _{2}S\ +$ little $FeO$

  3. $Cu _{2}O\ +$ little $FeS$

  4. $Cu _{2}O\ +$ little $FeO$

Show answer
Correct Option: A
Explanation:

In the extraction of copper, raw material used for the Bessemer converter is matte ($Cu _2S+FeS (little)$), where matte is formed in the blast furnace.

Formation of metallic copper from the sulphide ore in the commercial metallurgical process involves:

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

  1. $Cu _{2}S$ $+\frac{3}{2} O _{2}$ $\rightarrow$ $Cu _{2}O+$$SO _{2}$ ; $Cu _{2}O$+$C$ $\rightarrow$ $2Cu$+$CO$

  2. $Cu _{2}S+$ $\frac{3}{2}O _{2}$ $\rightarrow$ $Cu _{2}O+$ $SO _{2}$; $2Cu _{2}O+$ $Cu _{2}S$ $\rightarrow$ $6Cu+$$SO _{2}$

  3. $Cu _{2}S+2O _{2}\rightarrow CuSO _{4}$; $CuSO _{4} + Cu _{2}S\rightarrow 3Cu + 2SO _{2}$

  4. $Cu _{2}S+ \frac{3}{2}O _{2} \rightarrow 2Cu+ SO _{2}$ ; $Cu _{2}O+CO\rightarrow2Cu+CO _{2}$

Show answer
Correct Option: B
Explanation:

The commercial metallurgical process for the formation of metallic copper from the sulphide ore involves oxidation of $Cu _2S$ to $Cu _2O$  and auto reduction of a mixture of $Cu _2S$ and $Cu _2O$ to copper metal.

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

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

Blister copper is refined by stirring molten impure metal with green logs of wood because such a wood liberate hydrocarbon gases (like $CH {4}$). This process $X$ is called _____ and the metal contains impurities of $Y$ is ___________ .

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

  1. $X$= cupellation, $Y$= $CuO _{2}$

  2. $X$= polling, $Y$= $Cu _{2}O$

  3. $X$= polling, $Y$= $CuO$

  4. $X$= cupellation, $Y$= $CuO$

Show answer
Correct Option: B
Explanation:

The refining process of blister copper is known as polling.
The $Cu _2O$ impurities are present in the copper metal.
In presence of heat of molten metals, the green logs liberate hydrocarbon gases which reduce copper oxide into copper.

Roasting of copper pyrites is done:

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

  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

Show answer
Correct Option: A,B,C
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.

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

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

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

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

  1. Bessemerisation

  2. Parkes or Pattinson process

  3. Forth flotation

  4. None of these

Show answer
Correct Option: A
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.

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

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