Chemistry · Science General

Metallurgical Processes

1,403 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.

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Metallurgical Processes Questions

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

How do we separate two sulphide ores by froth floatation method?

  1. By using excess of pine oil.

  2. By adjusting proportion of oil to water or using depressant.

  3. By using collectors and froth stabilities like xanthates.

  4. By using some solvent in which one of the sulphides is soluble.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

By using depressants or adjusting proportion of oil to water, selective prevention of one sulphide ore from coming to the froth is possible.

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

An ore of tin containing, $FeCrO _4$ is concentrated by:

  1. gravity separation

  2. magnetic separation

  3. forth floatation

  4. leaching
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Magnetic separation based on differences in magnetic properties of the ore components.
  •  If either the ore or the gangue is attracted towards the magnetic field, then the separation is carried out by this method. 
  • For example, iron ores are attracted towards the magnet, hence, non–magnetic impurities can be separated from them using magnetic separation.
  • Here,$FeCrO _4$ being an iron ore can be separated by magnetic separation.
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Removal of the unwanted materials like sand, clays, etc. from the ore is known as __, ___ or _____.

  1. concentration, dressing, benefaction

  2. separation, refining, gangue

  3. magnetic separation, Purification, gangue

  4. washing, refining, amalgamation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Removal of the unwanted materials (e.g., sand, clays, etc.) from the ore is known as concentration, dressing or benefaction.

  • Before proceeding for concentration, ores are graded and crushed to a reasonable size. 

  • The concentration of ores involves several steps and the selection of these steps depends upon the differences in physical properties of the compound of the metal present and that of the gangue.
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

The significance of leaching in the extraction of aluminium is:

  1. it helps to remove the impurities like $SiO _2, Fe _2O _3,$ etc from the bauxite ore

  2. it converts the ore into oxide

  3. it reduces melting point of the ore

  4. it eliminates water from bauxite.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Bauxite is the principal ore of aluminium.  The impurities present in bauxite are $SiO _2$, iron oxides and titanium oxide ($TiO _2$). 
  •  $Al _2O _3$ is extracted out as sodium aluminate. The impurity, $SiO _2$ too dissolves forming sodium silicate. Other impurities are left behind.
$Al _2O _3+2NaOH+3H _2O \rightarrow 2Na[Al(OH) _4]$
  • Thus, leaching is used to remove the impurities present and hence option $A$ is the correct option.

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Sulphide ore of zinc/copper is concentrated by:

  1. forth floatation

  2. electromagnetic process

  3. gravity process

  4. distillation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Froth floatation method is used for removing gangue from sulphide ores. In this process, a suspension of the powdered ore is made with water.
  • Collectors and froth stabilizers are added to it. Collectors (e.g., pine oils, fatty acids, xanthates, etc.) enhance non-wettability of the mineral particles and froth stabilizers (e.g., cresols, aniline) stabilize the froth.
  • The mineral particles become wet by oils while the gangue particles by
water.
  • A rotating paddle agitates the mixture and draws air in it. As a result, the froth is formed which carries the mineral particles. The froth is light and is skimmed off. It is then dried for recovery of the ore particles.
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Sometimes it is possible to separate two sulphide ores by adjusting the proportion of oil to water by using depressants. When a depressant $NaCN$ is added to an ore containing $ZnS$ and $PbS$, what is the correct observation?

  1. $NaCN$ prevents $PbS$ from coming to the froth but allows $ZnS$ to come with froth
  2. $NaCN$ prevents $ZnS$ from coming to the froth but allows $PbS$ to come with froth
  3. $NaCN$ prevents frothing of both $ZnS$ and $PbS$, hence no froth is formed
  4. $NaCN$ does not act as depressant hence a mixture of $PbS$ and $ZnS$ is found in the froth
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Froth floatation method is used for removing gangue from sulphide ores. In this process, a suspension of the powdered ore is made with water.
  • It is possible to separate two sulphide ores by adjusting the proportion of oil to water or by using ‘depressants’.
  •  In the case of an ore containing $ZnS$ and $PbS$, the depressant used is $NaCN$. It selectively prevents $ZnS$ from coming to the froth but allows $PbS$ to come with the froth.
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

The oil used as frothing agent in froth floatation process is:

  1. coconut oil

  2. castor oil

  3. palmitic oil

  4. pine oil
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • Froth floatation method is used for removing gangue from sulphide ores. In this process, a suspension of the powdered ore is made with water.
  • Collectors and froth stabilizers are added to it. 
  • Collectors (e.g., pine oils, fatty acids, xanthates, etc.) enhance non-wettability of the mineral particles and froth stabilizers (e.g., cresols, aniline) stabilize the froth. 
  • The mineral particles become wet by oils while the gangue particles by water.
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Forth floatation process of concentration is based on the:

  1. preferential wetting properties with the frothing agent and water

  2. difference in the specific gravities of gangue and ore particles

  3. difference in solubility of ganaue and ore particles in frothing agent and water

  4. difference in reactivity of gangue and ore particles with water and frothing agent.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Froth floatation process method is used for removing gangue from sulphide ores.
  •  In this process, a suspension of the powdered ore is made with water. Collectors and froth stabilizers are added to it. 
  • Collectors (e.g., pine oils, fatty acids, xanthates, etc.) enhance non-wettability of the mineral particles and froth stabilizers (e.g., cresols, aniline) stabilize the froth.
  • The mineral particles become wet by oils while the gangue particles by water. 
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

For which of the following ores forth floatation method is used for concentration?

  1. Haematite

  2. Zinc blende

  3. Magnetite

  4. Carnallite
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Froth floatation method is used for removing gangue from sulphide ores. In this process, a suspension of the powdered ore is made with water
  • Among the given options Zinc blend ($ZnS$) is the only sulphide ore and hence Froth floatation process is used for its concentration.
  • Hence, option B is the right answer.
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Which of the following statements is correct about the role of collectors added during forth floatation process?

  1. Collectors enhance the non-wettability of ore particles

  2. Collectors enhance the wettability of gangue particles

  3. Collectors help in separating two sulphide ores present in the mixture

  4. Collectors help ore particles to settle down below the froth
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Froth floatation method is used for removing gangue from sulphide ores. In this process, a suspension of the powdered ore is made with water.
  • Collectors and froth stabilizers are added to it. Collectors (e.g., pine oils, fatty acids, xanthates, etc.) enhance non-wettability of the mineral particles and froth stabilizers (e.g., cresols, aniline) stabilize the froth.
  • The mineral particles become wet by oils while the gangue particles by water.
Multiple choice chemistry general principles of metallurgy concentration of ore concentration of ores principles of metallurgy

Which type of ores are concentrated by froth flotation process?

  1. Carbonates

  2. Sulphides

  3. Oxides

  4. Phosphates
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The froth flotation method is used to separate and concentrate ores by altering their surfaces to a hydrophobic or hydrophilic condition.


This method is based on the principle of the difference in the wetting properties of the ore and the gangue particles with the water and oil.


Therefore, sulphide ores preferably wetted by the oil and the gangue with the water.
Hence, option $(B)$ is correct.

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Froth floatation process is used for the :

  1. Oxide ores

  2. Sulphide ores

  3. Chloride ores

  4. All of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Froth floatation process is used for the sulphide ores. In this method, wetting of the ore by an oil takes place. A strong current of air is blown through the suspension, producing a heavy froth or foam on the surface. The metal sulphide is wetted by the oil but the gangues is not and the sulphide-oil mixture is carried to the surface by films of oil The froth is skimmed off, the gangue settles down on the bottom or remains underneath the froth.

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Concentration by froth floatation is applicable for which of the following ores?

  1. $Al _{2}O _{3}$
  2. $Te _{3}O _{4}$
  3. $Te _{2}O _{3}.3H _{2}O$
  4. $ZnS$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This method is used for those metals whose ore gets preferably wetted by the oil and the gangue by the water. The sulphide ores preferably wetted by the oil and the gangue with the water.

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Which of the method used for the concentration of sulfide ores?

  1. froth floatation

  2. smelting

  3. magnetic separation

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

This method is used for those metals whose ore gets preferably wetted by the oil and the gangue by the water. The sulphide ores preferably wetted by the oil and the gangue with the water.