Ground ore particles fall through the pulp. Air bubbles rise from the aerator at the bottom. A particle is only floatable if it is a liberated CaF₂ grain — collector reagent coats it and makes it hydrophobic, so on colliding with a bubble it attaches and rides upward into the froth. Locked (unliberated) grains and gangue stay hydrophilic and sink to tailings, though some gangue is mechanically entrained into the froth when foam load is high, diluting concentrate grade.
- Grind fineness — sets the liberation fraction: finer grinding frees more pure CaF₂ grains from the host rock.
- Collector dosage — raises the attachment probability of a liberated grain hitting a bubble.
- Air flow rate — controls bubble generation rate; more bubbles mean more collision chances but also faster foam build-up.
- Vein type — sets what fraction of the feed is CaF₂-bearing versus barren gangue.
Foam that isn't skimmed keeps growing; past ~80% load, entrainment rises and the froth becomes unstable.