Flotation
Definition and meaning of Flotation in chemistry.
Flotation (froth flotation) is a physical separation process that concentrates finely ground mineral particles by exploiting differences in surface wettability: air bubbles rising through a water-based slurry selectively carry hydrophobic particles to the surface as a froth, leaving hydrophilic particles behind.
In more detail
In practice, crushed ore is mixed with water to form a pulp, and a collector reagent (often a xanthate) adsorbs onto the target mineral's surface, converting it from hydrophilic to hydrophobic. Air is sparged through the pulp; hydrophobic particles attach to the bubbles and rise into a stable froth layer, sustained by a frothing agent, while unwanted gangue particles remain wetted and sink. The froth is skimmed off as a mineral concentrate. Depressants and activators fine-tune selectivity when multiple sulfide minerals are present together.
Key facts
| Field | Physical Chemistry |
|---|---|
| Governing principle | Differential surface wettability (hydrophobic vs. hydrophilic) |
| Key reagents | Collectors (e.g., xanthates), frothers, depressants, activators |
| Major application | Concentration of sulfide ores (Cu, Pb, Zn, Ni) |
In copper ore processing, ground ore containing chalcopyrite (CuFeS2) is treated with a xanthate collector, making the copper sulfide grains hydrophobic; aeration lifts them into a froth that is skimmed off, concentrating the copper mineral away from silicate gangue.
Frequently asked questions
What does a collector do in flotation?
A collector is a surfactant reagent that adsorbs onto a specific mineral's surface, rendering it hydrophobic so it will attach to rising air bubbles instead of staying wetted by water.