Tag: concentration of ores

Questions Related to concentration of ores

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

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

  1. aluminium

  2. silver

  3. copper

  4. gold

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Correct Option: A,B,C,D
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.

Select correct statement(s) about differentiation floatation.

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

  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

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Correct Option: D
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.

Froth flotation is a process of _____________.

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

  1. oxidation

  2. reduction

  3. refining

  4. concentration

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Correct Option: D
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 $FeCr _2O _4$.

Bauxite is concentrated by:

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

  1. Chemical method

  2. Roasting

  3. Magnetic separation

  4. Froth flotation process

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Correct Option: A
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.

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

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

  1. they are light

  2. their surface is not easily wetted by water

  3. they bear electrostatic charge

  4. they are insoluble

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Correct Option: B
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.

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

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

  1. Levigation

  2. Magnetic separation

  3. Leaching

  4. Froth fioatation

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Correct Option: C
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$

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

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

  1. Gravity separation

  2. Froth flotation process

  3. Electromagnetic separation

  4. Smelting

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Correct Option: D
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.

Chemical leaching is not useful in the concentration of:

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

  1. copper pyrite

  2. bauxite

  3. galena

  4. cassiterite

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Correct Option: A,C,D
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.

Froth floatation process is used to concentrate magnetic ores.

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

  1. True

  2. False

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Correct Option: B
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 $(FeS)$.

 Name the metal which are associated with the following term in their extraction from their ores. Magnetic separation:

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

  1. tin stone and chromite ore

  2. copper stone and chromite ore

  3. tin stone and iron ore

  4. none of these

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Correct Option: C
Explanation:
 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)