Tag: concentration of ores

Questions Related to concentration of ores

How is scrap-iron separated from other wastes in a scrap yard?

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

  1. Sublimation

  2. Magnetic separation

  3. Handpicking

  4. Winnowing

Show answer
Correct Option: B
Explanation:

Scarp Iron is a magnetic substance whereas others are not. So, they are separated by Magnetic Separation.

Chromite is concentrated by:

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

  1. chemical separation

  2. magnetic separation

  3. hydraulic washing

  4. froth floatation

Show answer
Correct Option: B
Explanation:

Chromite is $[Fe(CrO _{2}) _{2}]$
Magnetic separation depends on its difference in the magnetic separation of the ores and gangues.

Which of the following is not a method of enrichment of ore?

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

  1. Hydraulic washing

  2. Froth floatation

  3. Magnetic seperation

  4. None of the above

Show answer
Correct Option: D
Explanation:

Enrichment of ore means concentration or purification of ore. It can be done by hydraulic washing, magnetic separation, chemical separation.

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

Show answer
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