Question

The correct statements regarding froth floatation method in metallurgy are
I. Used for the purification of sulphide ores
II. Used for the roasting of sulphide ores
III. It is based on the relative densities of gangue and ore particles
IV. It is based on the wetting properties of gangue and ore particles in frothing agent and water

• A. I & IV only
• B. II & III only
• C. II & IV only
• D. I & III only

Hint:

Remember that froth flotation separates materials based on their surface properties, specifically wettability (hydrophobicity vs. hydrophilicity), and is a common technique for concentrating sulphide ores. It does not rely on density differences or involve chemical transformations like roasting.

Answer 1

The Correct Option is A

The froth flotation method is a selective separation process used in mineral processing to separate hydrophobic materials from hydrophilic materials.
It is widely used for the extraction and purification of sulphide ores.
Let's examine each statement: I.
**Used for the purification of sulphide ores:** Froth flotation is indeed primarily used for concentrating sulphide ores, such as copper sulphide (CuS), zinc sulphide (ZnS), and lead sulphide (PbS), by separating them from gangue (impurities like silica, clay, etc.
).
This statement is correct.
II.
**Used for the roasting of sulphide ores:** Roasting is a pyrometallurgical process where sulphide ores are heated strongly in the presence of excess air to convert them into metal oxides or sulphates.
Froth flotation is a physical separation method based on surface properties and is used before roasting in some cases, not as the roasting process itself.
This statement is incorrect.
III.
**It is based on the relative densities of gangue and ore particles:** While gravity separation methods rely on differences in densities, froth flotation is primarily based on the differences in the wettability (hydrophobicity and hydrophilicity) of the ore and gangue particles.
This statement is incorrect.
IV.
**It is based on the wetting properties of gangue and ore particles in frothing agent and water:** In froth flotation, the ore particles are preferentially wetted by oil (or a suitable collector) and become hydrophobic, attaching to air bubbles.
The gangue particles are preferentially wetted by water and remain in the aqueous phase.
Frothing agents stabilize the froth, allowing the hydrophobic ore particles to be carried to the surface and separated.
This statement is correct.
Therefore, the correct statements regarding the froth flotation method are I and IV.