In froth flotation, which reagent acts as an activator that enhances the floatability of specific minerals (e.g., activating sphalerite for subsequent collector action)?

Introduction / Context:
Flotation selectivity relies on modifiers: activators, depressants, pH regulators, and collectors. Activators render mineral surfaces more responsive to collectors.

Given Data / Assumptions:

• Sphalerite (ZnS) example: activation by copper ions.
• Collectors respond to altered surface chemistry.

Concept / Approach:
Copper sulphate provides Cu^2+ ions that exchange with surface Zn^2+, forming a more readily floatable copper-activated surface that adsorbs xanthates. Cresylic acid is a frother; carbonates are pH modifiers/buffers, not activators.

Step-by-Step Solution:
Identify reagent that specifically increases mineral responsiveness.Match to copper sulphate as a classic activator.

Verification / Alternative check:
Standard reagent schemes list copper sulphate as activator for ZnS and occasionally pyrite in certain systems.

Why Other Options Are Wrong:
Cresylic acid: frother.CaCO3/Na2CO3: pH regulation and depression/dispersion roles.Kerosene: hydrocarbon collector/dispersant in some systems, not an activator.

Common Pitfalls:
Confusing activators with collectors due to similar metallurgical outcomes (higher recovery).

Final Answer:
Copper sulphate