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 production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

The extraction of metals from oxide ores involve :

  1. reduction with carbon

  2. reduction with aluminium

  3. electrolyte reduction
  4. reduction with $CO$
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

During extraction of metals from oxide ores, the reduction of metal ore to crude metal can be carried out by using several methods such as pyrometallurgy, hydrometallurgy and electrometallurgy. Various reducing agents such as carbon, hydrogen, aluminum or other metals can be used. CO also reduces metal ores to crude metals.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Aluminothermy used for the spot welding of large iron structures is based upon the fact that :

  1. As compared to iron, aluminium has greater affinity for oxygen.

  2. As compared to aluminium, iron has greater affinity for oxygen.

  3. Reaction between aluminium and oxygen is endothermic..

  4. Reaction between iron oxide and aluminium is exothermic.
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

Aluminothermy used for the spot welding of large iron structures is based upon two facts 
(i) As compared to iron, aluminum has greater affinity for oxygen. hence, aluminum acts are reducing agent.
(ii) Reaction between iron oxide and aluminum is exothermic. High temperature is involved in the reaction.
Aluminum reduces iron oxide to iron. 

$Fe _2O _3 + 2 Al \rightarrow 2 Fe + Al _2O _3$

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

The methods chiefly used for the extraction of lead and tin from their ores are respectively _________________.

  1. self reduction and carbon reduction

  2. self reduction and electrolytic reduction

  3. carbon reduction and self reduction

  4. cyanide process and carbon reduction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The methods chiefly used for the extraction of lead and tin from their ores are respectively self reduction and carbon reduction. Self reduction for lead is as follows.
$2PbS+3O _2 \rightarrow 2PbO+2SO _2 \uparrow$
$PbS+2O _2 \rightarrow PbSO _4$
$2PbO + PbS \rightarrow 3Pb+SO _2 \uparrow$
$PbSO _4+PbS \rightarrow 2Pb+2SO _2 \uparrow$
Carbon reduction for tin is as follows.
$SnO _2+2C \rightarrow Sn+2CO \uparrow$

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Auto reduction process is used for the extraction of:

  1. Cu

  2. Hg

  3. Pb

  4. Al
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation
Auto-reduction or air reduction is a very popular reaction in metallurgy. 

It is a process in which 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 of sulphide ore in absence of air to give the metal and sulphur dioxide.
Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

The extraction of metals from oxide ores involve(s) :

  1. reduction with carbon

  2. reduction with aluminium

  3. electrolytic reduction

  4. reduction with CO
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

During extraction of metals from oxide ores, the reduction of metal ore to crude metal can be carried out by using several methods such as pyrometallurgy, hydrometallurgy and electrometallurgy. Various reducing agents such as carbon, hydrogen, aluminum or other metals can be used. CO also reduces metal ores to crude metals.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Lead obtained from galena ore (PbS) by air reduction or carbon reduction process contains base metal (Cu, Bi, As, Sn, Zn) as impurities. Gelatin acts as an addition agent in the electrolysis of Pb. In the presence of gelatin, Pb becomes :

  1. hard and brittle

  2. soft and rubbery

  3. smooth and uniform

  4. only brittle
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Lead obtained contains impurities like $Cu, Sb, Sn, As, Ag, Au, etc.$ which make it hard. During electrolytic refining of lead, the electrolyte $(PbSiF _6+H _2SiF _6)$ is mixed with a little gelatin. Gelatin is added for smooth and uniform deposition of lead in this process. 

Hence, the correct option is (C).
Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Pb is a very important element of carbon family. It forms a number of compounds which are very useful in industries. The process of removal of base metals (Cu, Sn, Bi, As) from lead is called:

  1. softening process

  2. liquation

  3. parke's process

  4. cupellalion
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For the removal of base metals the impure bullion is charged to a softening furnace whereby oxidation these elements form drosses or slags and, with some lead, are skimmed from the bath. This is the softening process. 

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

The main source of lead is PbS. It is converted to Pb by:- 


(i) ${PbS\xrightarrow[\Delta]{air }PbO+SO _2\xrightarrow[\Delta]{C}Pb+CO _2}$


(ii) ${PbS\xrightarrow[\Delta]{air }PbO+PbS\xrightarrow[]{\Delta}Pb+SO _2}$ 

Self reduction process is:

  1. i

  2. ii

  3. both

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

Self reduction process of Pb is

$PbS + 2PbO \rightarrow   3Pb + SO _2$
so (ii) is self reduction process.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Which one of the following metals can not be extracted by using Al as a reducing agent ________________.

  1. $\displaystyle Na$ from $\displaystyle { Na } _{ 2 }O$
  2. $\displaystyle Cr$ from $\displaystyle { Cr } _{ 2 }{ O } _{ 3 }$
  3. $\displaystyle Mn$ from $\displaystyle { MnO } _{ 2 }$
  4. $\displaystyle Fe$ from $\displaystyle { Fe } _{ 2 }{ O } _{ 3 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

As sodium  (alkali metal) is more reactive than Al so it cannot be extracted from $Na _2O$ by using Al as a reducing agent.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Sequence the following steps involved generally in the extraction of a metal in pure form from its ore.
(a) The metal obtained from its oxide require further purification for end use.
(b) The ore should be converted to its oxide form.
(c) The ore is beneficial to us if it is handpicked then metal crushed and ground, and later subjected to pulverization as per the requirement
(d) The ore in the form of oxide is required to be reduced.
(e) Dressed ore is required for it to be concentrated.

  1. e c b d a

  2. c e b d a

  3. c e b a d

  4. c e d b a
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

(c) The ore is beneficial to us if it is handpicked then metal crushed and ground, and later subjected to pulverization as per the requirement
(e) Dressed ore is required for it to be concentrated.
(b) The ore should be converted to its oxide form.
(d) The ore in the form of oxide is required to be reduced.
(a) The metal obtained from its oxide require further purification for end use.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Prior to reduction, metal sulphide and carbonates are converted into oxides because:

  1. carbonates, sulphides are heavy molecules

  2. it is easier to obtain a metal from its oxide as compared to its sulphides and carbonates

  3. it is easy to heat oxide compared to sulphides and carbonates
  4. both $A$ and $B$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

It is easier to obtain a metal from its oxide, as compared to its sulphides and carbonates. Therefore, prior to reduction, the metal sulphides and carbonates must be converted to metal oxides.