Tag: general principles of metallurgy

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

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
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

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

  1. froth floatation

  2. roasting

  3. bessemerisation

  4. leaching
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

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

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

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

  1. $ZnH _2 + N _2$
  2. $Zn _3N _2 + H _2$
  3. $Zn(NH _2) _2 + H _2$
  4. $[Zn(NH _3) _4]^{2+}$
Reveal answer Fill a bubble to check yourself
D Correct answer
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 $ 

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, the smelt formed in the blast furnace contains:

  1. $Cu _{2}S\ +$ little $FeS$
  2. $Cu _{2}S\ +$ little $FeO$
  3. $Cu _{2}O\ +$ little $FeS$
  4. $Cu _{2}O\ +$ little $FeO$
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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

  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. $Cu _{2}S+ \frac{3}{2}O _{2} \rightarrow 2Cu+ SO _{2}$ ; $Cu _{2}O+CO\rightarrow2Cu+CO _{2}$
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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

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

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 ___________ .

  1. $X$= cupellation, $Y$= $CuO _{2}$
  2. $X$= polling, $Y$= $Cu _{2}O$
  3. $X$= polling, $Y$= $CuO$
  4. $X$= cupellation, $Y$= $CuO$
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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.

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

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