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 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

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.

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

Froth flotation process is based upon :

  1. Magnetic property of gangue

  2. Specific gravity of ore particle

  3. Preferential wetting of ore particle by oil

  4. Preferential wetting of gangue particle by oil
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Froth flotation relies on the difference in surface properties between ore and gangue. Ore particles are preferentially wetted by oil (hydrophobic), while gangue particles are wetted by water (hydrophilic).

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

Leaching is commercially carried out for in the concentration of:

  1. galena

  2. argentite

  3. copper pyrites

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

Leaching is a process in which the ore is dissolved in a suitable solvent, where the impurities remain undissolved. This method is used in the extraction of $Ag$ from Argentite where is, the ore is dissolved in sodium cyanide solution.

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

Which of the following method used for the concentration of copper pyrites?

  1. Magnetic seperation

  2. Gravity seperation

  3. Froth Floatation process

  4. None
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
This method is used when a higher ore contains impurities with higher density. This method is used for the concentration of Sulphide ores. (Eg: Copper pyrites, iron pyrites, Galena, Zinc blende etc.) 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.
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Which of the following process is used for concentration of ore?

  1. Froth flotation

  2. Electrolytic methods

  3. Smelting

  4. Hoop's process
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Froth flotation method is used for the concentration of sulphide ores. 


The method is based on the preferential wetting properties with the frothing agent and water. In the given options, Galena (PbS) is the only sulphide ore.

Hence, option A is correct.