Tag: principles of metallurgy

Questions Related to principles of metallurgy

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

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

  1. Hydrautic washing

  2. Magnetic separation

  3. Froth floatation

  4. None of the above

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Correct Option: C
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.

In froth floatation process, gangue particles are wetted by pine oil.

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

  1. True

  2. False

Show answer
Correct Option: A
Explanation:
Froth flotation is a process to purify sulfide ores, in presence of pine oil. The oil acts as hydrophobic agent and forms froth with hydrophobic impurities (gangue) which is skimmed off from the surface leaving behind the concentrated mineral.
Wet pine oil is used in froth flotation process because it does not have an affinity towards water (because of the hydrophobic chemicals as its constituents)and it attracts impurities which can be washed away.
Hence, it is true.

Identify the principle behind the concentration of bauxite ore:

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

  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 $Al _2O _3$

Show answer
Correct Option: C
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.

The method used for the concentration of sulphide ores is:

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

  1. froth floatation

  2. smelting

  3. magnetic separatio

  4. gravity separation

Show answer
Correct Option: A
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.

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

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

  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 $Zn{ \left( CN \right) } _{ 3 }^{ - }$

Show answer
Correct Option: A
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.

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

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

  1. zinc

  2. zinc oxide

  3. silver oxide

  4. zinc sulphide

Show answer
Correct Option: A
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.
$4Au +8CN^-+2H _2O +O _2 \rightarrow 4[Au(CN) _2]^-+4OH^-$

Which of the following is commonly used to produce foam in froth floatation process?

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

  1. Pine oil

  2. Cresol

  3. NaCN

  4. Xanthate

Show answer
Correct Option: D

Which of the following ore is best concentrated by froth flotation method ?

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

  1. Galena

  2. Cassiterite

  3. Magnetite

  4. Zinc blende

Show answer
Correct Option: A,D
Explanation:

Galena ($PbS$) and zinc blende ($ZnS$) are sulphide ores. Cassiterite $SnO _{2}$ (oxide ore), and Magnetite $Fe _{3}O _{4}$ (oxide ore) are not sulphide ore. The froth flotation process is used to concentrate sulphide ores, based on preferential wetting properties with frosting agent and water.

Hence option $A$ and $D$ are correct.

In froth floatation process, gangue articles are wetted by pine oil.

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

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Froth flotation is selective separating the hydrophilic particles from hydrophobic. It is used for copper and lead sulfide ores. It is the preferential wetting of ore with pine oil to remove gangue or impurities.

Minerals from which metals can be preferably extracted are called :

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

  1. Ores

  2. Source

  3. Alloy

  4. None of these

Show answer
Correct Option: A
Explanation:

$\Rightarrow$ Minerals occur naturally in the Earth.

$\Rightarrow$ The minerals from which the metals are extracted without loss is called ores.
Example:
Many minerals are there for Aluminium extraction. But Bauxite extraction is of low cost. So Bauxite is only called ore of Aluminium. But remaining are only minerals.