The role of depressants in 'Froth Floation method' is to

In the Froth Floatation method, depressants are chemicals that are added to selectively prevent certain mineral particles from forming froth, thereby allowing separation of different sulfide ores.

The froth floatation process is used for the concentration of sulfide ores. The ore is mixed with water and a frothing agent (like pine oil). Air is blown through the mixture, and the sulfide ore particles (which are preferentially wetted by oil) rise with the froth, while the gangue (which is preferentially wetted by water) settles down.

When an ore contains two or more sulfide minerals (e.g., ZnS and PbS), depressants are used to selectively prevent one of the sulfide ores from coming to the froth. For example, NaCN is used as a depressant for ZnS when separating it from PbS. NaCN forms a layer of zinc cyanide on ZnS particles, preventing them from coming to the froth while PbS floats.

Option A: Selectively prevent one component of the ore from coming to the froth — this is correct and describes the exact role of depressants.

Option B: Reduce oil consumption — this is not the role of depressants.

Option C: Stabilize the froth — this is the role of froth stabilizers, not depressants.

Option D: Enhance non-wettability — this is the role of collectors, not depressants.

Therefore, the correct answer is Option A.