Tag: principles of metallurgy

Questions Related to principles of metallurgy

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

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

  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

Show answer
Correct Option: A
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.

Which of the following ores is concentrated by chemical leaching method?

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

  1. Cinnabar

  2. Argentite

  3. Copper pyrites

  4. Galena

Show answer
Correct Option: B
Explanation:
  • In the metallurgy of silver , the respective metal is eached with a dilute solution of NaCN or KCN in the presence of air, which supplies $O _2$. The metal is obtained later by replacement reaction.
  • The reactions involved are-
$4Ag+8CN^{-}+2H _2O+O _2 \rightarrow 4[M(CN) _2]^{-}+4OH^{-}$

$2[Ag(CN) _2]^{-}+Zn \rightarrow [Zn(CN) _4]^{2-}+2Ag$
  • Hence, Argentite being an ore of SIlver is concenrated by leaching.

Which type of ores are concentrated by froth flotation process?

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

  1. Carbonates

  2. Sulphides

  3. Oxides

  4. Phosphates

Show answer
Correct Option: B
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.

When $ZnS$ and $PbS$ minerals are present together, then $NaCN$ is added to separate them in the froth flotation process as a depressant, because:

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

  1. $Pb(CN) _2$ precipitated while no effect on $ZnS$

  2. $ZnS$ forms soluble complex $Na _2 Zn(CN) _4$

  3. $PbS$ forms soluble complex $Na _2Pb(CN) _4$

  4. both $(a)$ and $(b)$

Show answer
Correct Option: B
Explanation:

$NaCN$ prevents $ZnS$ from forming the froth by reacting with it to from complex $Na _2[Zn(CN) _4]$ and acts as a depressant. While it does not prevent $PbS$ from forming froth and both the ores can easily be separated.

Froth floatation process is used for the :

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

  1. Oxide ores

  2. Sulphide ores

  3. Chloride ores

  4. All of these

Show answer
Correct Option: B
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.

Which of the following fraction of coal tar distillation is obtained at $270^{\circ} - 360^{\circ} C$?

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

  1. Light oil

  2. Middle oil

  3. Green oil

  4. Heavy oil

Show answer
Correct Option: C
Explanation:

Green oil (anthracene oil) is obtained at $270 - 360^{\circ} C$ by distillation of coal tar. It mainly has anthracene and phenanthrene.

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

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

  1. $Al _{2}O _{3}$

  2. $Te _{3}O _{4}$

  3. $Te _{2}O _{3}.3H _{2}O$

  4. $ZnS$

Show answer
Correct Option: D
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.

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

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

  1. froth floatation

  2. smelting

  3. magnetic separation

  4. gravity separation

Show answer
Correct Option: A
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.

In froth flotation process, pine oil is usually added to the gangue particles in the ore.

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

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

In froth flotation process, pine oil is usually added to the suspension of the powdered ore. Pine oil enhance non-wettability of the mineral particles.

Which of the following compound is used as froth stabliser?

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

  1. Fatty acid

  2. Aniline

  3. Xanthates

  4. Phosphoric acid

Show answer
Correct Option: B
Explanation:

Here answer is option B

Aniline stabilize the froth before it is taken out for further treatment.
In this process, a suspension of a powdered ore is made with water. In this process, a suspension of a powdered ore is made with water. Collectors like pine oil, fatty acids and xanthates are added to it. Froth stabilizer like cresols, aniline stabilize the forth