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.

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Metallurgical Processes Questions

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

Sulphide ore of copper can be concentrated by froth floatation process.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Froth Floatation Process:- The process is best suitable for sulphide ores. The process is based on different wetting characteristics of the ore and gangue particles with water and pine oil. The ore is wetted by oil and impurities are wetted by water. Ore particles are adsorbed on potassium or sodium ethyl xanthate (as collector) and come at the surface along with the froth. Froth stabilisers (cresols, aniline) stabilise the froth. So sulphide of copper can be concentrated by froth floatation process.
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Sulfide ores are usually dressed by the _____ process.

  1. sieve process

  2. froth floatation

  3. magnetic floatation

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Froth floatation process is based on the principle that the metallic sulphide particles of ore are preferentially wetted by oil and the gangue particles by water.
Sulphide ores being lighter are easily wetted by oil to come on the surface of solution with froths during froth floatation process, leaving behind heavy matter of gangue wetted by water.
Sulphide ores are usually dressed by froth floatation process.

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

The oil used in the froth floatation method for the purification of ore is _________.

  1. Coconut oil

  2. Olive oil

  3. Pine oil

  4. Castor oil
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Froth Floatation process is suitable for sulphide ores. The process is based on different wetting characteristics of the ore and gangue particles with water and pine oil. 

The ore is wetted by oil and impurities are wetted by water. Ore particles are adsorbed on potassium or sodium ethyl xanthate (as a collector) and come at the surface along with the froth. Froth stabiliser (cresols, aniline) stabilise the froth. 

So, the correct option is $C$
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

During concentration of _____ ores by froth floatation process potassium ethyl xanthate is added.

  1. sulphide

  2. carbonate

  3. halide

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

During concentration of sulphide ores by froth floatation process potassium ethyl xanthate is added.
Ethyl xanthate, potassium ethyl xanthate and similar compounds compounds behaves as collector and attaches themselves by polar groups to ore particles making that hydrophobic and i.e., why ore particles are passed into froth.

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

Ores like magnetite or tungstates in tin ores are concentrated by ______.

  1. Froth floatation

  2. Magnetic separation

  3. Gravity separation

  4. Electrostatic separation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Magnetic Separation:- This method is adopted when either ore or the impurities are magnetic in nature. They are separated from each other by means of magnetic separators.
Eg: $SnO _2$ (Non magnetic) in $Fe _3O _4$ (magnetic)
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Ore dressing for iron is done by:

  1. froth floatation process

  2. magnetic separation

  3. hand picking

  4. all of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the field of extractive metallurgy, mineral processing, also known as ore dressing, is the process of separating commercially valuable minerals from their ores. 

Ore dressing for iron is done by magnetic separation.
So answer is B.

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

Any physical and chemical process by which low grade ores are concentrated, is __________.

  1. froth flotation

  2. crushing and then screening

  3. hand picking

  4. washing in zigs
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Froth flotation is a process for selectively separating hydrophobic materials from hydrophilic. Any physical and chemical process by which low grade ores are concentrated is called froth flotation.

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

An ore on heating in air forms $SO _{2}$. State the process that will be used for its concentration.

  1. Hydrautic washing

  2. Magnetic separation

  3. Froth floatation

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Whenever a metal sulphide is heated in air, sulphur dioxide is formed as one of the products. A sulphide ore is concentrated by the froth floatation process.

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

Identify the principle behind the concentration of bauxite ore:

  1. magnetic property of impurities in white bauxite
  2. low specific gravity of $Al _2O _3$
  3. amphoteric nature of $Al _2O _3$
  4. high melting point of $Al _2O _3$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

An amphoteric compound is a compound that can react both as an acid as well as a base. For example, $ Al _{ 2 }{ O } _{ 3 } $. 

Hence, this principle is behind the concentration of bauxite ore. In this process $ Al _{ 2 }{ O } _{ 3 } $ first acts as an acid then as a base.

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

The method used for the concentration of sulphide ores is:

  1. froth floatation

  2. smelting

  3. magnetic separatio

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

Froth flotation is a process for selectively separating hydrophobic materials from hydrophilic. The principle of froth flotation process is that sulphide ores are preferentially wetted by the pine oil, whereas the gangue particles are wetted by the water. Hence the method used for the concentration of sulphide ores is froth flotation.

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

Extraction of gold $\left( Au \right) $ involves the formation of complex ions '$X$' and '$Y$'.
        Gold ore $\underset { C{ N }^{ - },{ H } _{ 2 }O,{ O } _{ 2 } }{ \underrightarrow { \quad Roasting\quad  }  } \quad H{ O }^{ - }+'X'\quad \underrightarrow { \quad \quad \quad Zn\quad \quad \quad  } \quad 'Y'+Au$
'$X$' and '$Y$' are respectively

  1. $Au{ \left( CN \right) } _{ 2 }^{ - }$ and $Zn{ \left( CN \right) } _{ 4 }^{ 2- }$
  2. $Au{ \left( CN \right) } _{ 4 }^{ 3- }$ and $Zn{ \left( CN \right) } _{ 4 }^{ 2- }$
  3. $Au{ \left( CN \right) } _{ 3 }^{ - }$ and $Zn{ \left( CN \right) } _{ 6 }^{ 4- }$
  4. $Au{ \left( CN \right) } _{ 4 }^{ - }$ and $Zn{ \left( CN \right) } _{ 3 }^{ - }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Extraction of gold $(Au)$ involves the formation of complex ions $'X'$ and $ 'Y'. 'X'$ and $'Y'$ are $\displaystyle Au{ \left( CN \right)  } _{ 2 }^{ - }$ and $\displaystyle Zn{ \left( CN \right)  } _{ 4 }^{ 2- }$ respectively

 Gold ore $\displaystyle \underset { C{ N }^{ - },{ H } _{ 2 }O,{ O } _{ 2 } }{ \underrightarrow { \quad Roasting\quad  }  } \quad H{ O }^{ - }+\underset {'X'}{Au{ \left( CN \right)  } _{ 2 }^{ - }} \quad \underrightarrow { \quad \quad \quad Zn\quad \quad \quad  } \quad \underset {'Y'}{Zn{ \left( CN \right)  } _{ 4 }^{ 2- }}+Au \downarrow$

Note:
The complex X is water soluble.
More electropositive zinc displaces gold from complex.

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

During leaching, gold is recovered from the solution by the addition of ______.

  1. zinc

  2. zinc oxide

  3. silver oxide

  4. zinc sulphide
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Gold is recovered from the solution by the addition of zinc.
$  2[Au(CN) _2]^- + Zn\rightarrow  [Zn(CN) _4]^{2+} +2 Au$
Note:
Gold ore is concentrated by leaching with sodium cyanide in presence of air.
$4Au +8CN^-+2H _2O +O _2 \rightarrow 4[Au(CN) _2]^-+4OH^-$