Question

The role of depressants in ‘Froth Floation method’ is to

• A. Selectively prevent one component of the ore from coming to the froth
• B. Reduce the consumption of oil for froth formation
• C. Stabilize the froth
• D. Enhance non-wettability of the mineral particles.

Answer 1

The Correct Option is A

The given question pertains to the Froth Flotation method, which is a process used for the concentration of ores. The role of various additives like depressants, collectors, and frothers in this method is crucial for its effectiveness.

Correct Answer Explanation: The correct option is: "Selectively prevent one component of the ore from coming to the froth."

Froth Flotation is a process used for selectively separating hydrophobic materials from hydrophilic ones. It is used for the concentration of sulfide ores. In this process, a fine powder of the ore is mixed with water and oil is added. When the mixture is agitated, the ore particles, which are often finely ground, tend to become minimized, forming froth at the surface. Certain reagents, such as depressants, are added to enhance the selectivity of the flotation process.

Depressants play a significant role in the Froth Flotation method. Their primary function is to selectively prevent the formation of froth by certain types of ore particles while allowing other types to form froth. This selectivity is crucial when dealing with ore mixtures where we wish to separate one mineral from undesirable gangue material or other minerals. For example, in the case of a zinc and lead sulfide ore mixture, NaCN can act as a depressant to prevent zinc sulfide from forming froth and allow only lead sulfide to rise with the froth.

Why Other Options are Incorrect:

• Reduce the consumption of oil for froth formation: This is not a direct role of depressants. Depressants are added to control the selectivity of the flotation process, not to reduce oil consumption.
• Stabilize the froth: Froth stabilization is typically achieved using frothers, not depressants. Frothers help create a stable froth layer on top of the flotation cell.
• Enhance non-wettability of the mineral particles: This is the role of collectors, which are added to increase the hydrophobicity (non-wettability) of the mineral particles, making them prone to attach to bubbles and rise to the surface.

Understanding the specific roles of these reagents helps in optimizing the Froth Flotation method for more efficient ore processing.