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

Froth floatation:

  1. is a physical method of separating mineral from the gangue

  2. is a method to concentrate the ore depending on the difference in wetability of gangue and the ore

  3. is used for the sulphide ores

  4. is a method in which impurities sink to the bottom
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

(A) The concentration of ore involves physical and chemical methods. Froth floatation method is the physical method for the separating mineral from the gangue.
(B) It  is based on the difference in wettability of different minerals.
The metallic sulphide particles of ore are preferentially wetted by oil and the gangue particles by water.
(C) Froth floatation process used for the concentration of sulphide ore.
(D) In this method impurities sink to the bottom and the ore particles rise to the surface alongwith the froth.

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

The chemical treatment of the ore for concentration is done in the case of :

  1. aluminium

  2. silver

  3. copper

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

The chemical treatment of the ore for concentration is done  when ore is required in very pure form .
This method is used for the purification of bauxite ($Al _2O _3$ an ore of aluminum ) which contains ferric oxide, titanium oxide and silica as impurities.
It is also used for the treatment of gold, silver and copper.

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

Select correct statement(s) about differentiation floatation.

  1. It is used to concentrate mixture of sulphides at different stages

  2. Zinc sulphate is used to depress zinc sulphide and PbS forms froth
  3. Copper sulphate is used to active depressed lead sulphide and $O _2$ is blown to make froth

  4. All of the above are correct statements
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In differentiation flotation, zinc sulphate is depresses zinc sulphide and PbS forms froth copper sulphate activate depressed lead sulphide. Froth is made by blowing oxygen. Thus, all the given statements are correct.

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

Froth flotation is a process of _____________.

  1. oxidation

  2. reduction

  3. refining

  4. concentration
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Froth flotation is a process of  concentration. Froth floatation process is suitable for sulphide ores It is based on the difference in wetting properties of the ore and gangue with water and oil. This method is used for the concentration of $FeCr _2O _4$.

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

Bauxite is concentrated by:

  1. Chemical method

  2. Roasting

  3. Magnetic separation

  4. Froth flotation process
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The bauxite is purified by the Bayer Process. First the ore is mixed with a hot concentrated solution of sodium hydroxide. The $NaOH$ will dissolve the oxides of aluminum and silicon but not other impurities such as iron oxides, which remains insoluble. The insoluble materials are removed by filtration.This method is called the chemical method.

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

In the froth floatation process, for the beneficiation of ores, the ore particles float because ______________.

  1. they are light

  2. their surface is not easily wetted by water

  3. they bear electrostatic charge

  4. they are insoluble
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the froth floatation process, for the benefaction of ores, the ore particles float because their surface is not easily wetted by water. This method is base on the difference in the wetting properties of ores and gangue particles with the water and oil.

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

Which of the following process is not a physical process of separation?

  1. Levigation

  2. Magnetic separation

  3. Leaching

  4. Froth fioatation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Leaching involves the treatment of the ore with a suitable reagent to make it soluble while impurity remains insoluble. The ore is recovered from the solution by suitable chemical method.

For example Bayer's process:
Bauxite ore contains impurities like $Fe _2O _3$, $TiO _2$  and $SiO _2$. So, when it dissolve in aq. NaOH/pressure + 150°C T, bauxite dissolves but others donot dissolve. 
$Al _2O _3 + 2NaOH \rightarrow 2NaAlO _2 + H _2O$
$ NaAlO _2 + 2H _2O \rightarrow Al(OH) _3 + NaOH$

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

Which one of the following is not a method of concentration of metals?

  1. Gravity separation

  2. Froth flotation process

  3. Electromagnetic separation

  4. Smelting
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Smelting is not a method of concentration of metals.

Smelting is a process of extraction of metal in its molten state by any reducing agent in the presence of flux. 

For example: oxides of less electropositive metals like Pb, Zn, Fe, Cu are reduced by any other reducing agents.
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Chemical leaching is not useful in the concentration of:

  1. copper pyrite

  2. bauxite

  3. galena

  4. cassiterite
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation
Chemical leaching is a process widely used in extractive metallurgy where ore is treated with chemicals to convert the valuable metals within into soluble salts while impurity remains insoluble.

Examples : copper pyrites, galena and cassiterite.

Hence options A,C & D are correct.
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Froth floatation process is used to concentrate magnetic ores.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Froth floatation process is used to concentrate sulphide ores. In some cases, sulphide ores of copper, zinc and lead concentration are brought by this method. It is the referential wetting of the ore by an oil. A strong current of air is blown through the suspension producing a heavy froth e.g. Galena $(PbS)$ is associated with Sphalerite $(ZnS)$ and Pyrite $(FeS)$.