Tag: general principles of metallurgy

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

INCORRECT Statement about froth floatation  method is.

  1. it is used to remove gangue from sulphide ores

  2. the mineral particles become wet by oils while gangue particles become wet by water

  3. collectors stabilize the froth

  4. to separate a mixture of ZnS and PbS depressant used is NaCN
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Collectors (like xanthates) are used to make the mineral particles water-repellent (hydrophobic) so they attach to air bubbles, whereas frothers are the agents that actually stabilize the froth.

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

ASSERTION: $CuFeS _{2}$ is concentrated by froth floatation method.
REASON: $CuFeS _{2}$ is the main ore of copper.

  1. If both assertion and reason are CORRECT, and reason is the CORRECT explanation of the assertion

  2. If both assertion and reason are CORRECT, but reason is NOT the CORRECT explanation of the assertion

  3. If assertion is CORRECT but reason is INCORRECT

  4. If assertion is INCORRECT but reason is CORRECT
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Chief ore of copper is copper pyrite ($CuFeS _{2}$). It is a sulphide ore and sulphide ores are concentrated by froth flotation method.

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

Froth flotation process used for the concentration of sulfide ore _______________.

  1. is based on the difference in wettability of different minerals
  2. uses sodium ethly xanthate, $C _{2}H _{5}OCS _{2}Na$ as collector
  3. uses $NaCN$ as depressant in the mixture of ZnS and PbS when ZnS forms soluble complex and Pbs forms froth

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

(A) Froth floatation process used for the concentration of sulphide ore 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.
(B) Froth floatation process used for the concentration of sulphide ore uses sodium ethyl xanthate, $C _{2}H _{5}OCS _{2}Na$ as collector. Other examples of collector include ethyl xanthate and potassium ethyl xanthate. They attach themselves to the grains of mineral by polar groups so that minerals become water repellent and pass on into the froth.
(C) Froth floatation process used for the concentration of sulphide ore uses NaCN as depressant in the mixture of ZnS and PbS when ZnS forms soluble complex and Pbs forms froth. Other depressant used is KCN.
Depressants depress the floating property of one of the components of the ore and help in the separation of different minerals present in the same ore.
Thus, all of the above statements are correct.

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

ASSERTION: In froth floatation process, sodium ethyl xanthate is used as a collector.
REASON: Sulphide ores are water soluble.

  1. If both assertion and reason are CORRECT, and the reason is the CORRECT explanation of the assertion.

  2. If both assertion and reason are CORRECT, but the reason is NOT the CORRECT explanation of the assertion.

  3. If assertion is CORRECT but reason is INCORRECT.

  4. If assertion is INCORRECT but reason is CORRECT.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Froth Flotation: The process is based on the principle of preferential wetting of ore particles by the oil and gangue by water. In this process, sodium ethyl xanthate is used as a collector. 

The sulfide ores are highly insoluble in water.

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.