How froth flotation lifts out minerals

Ground ore is mixed with water and chemicals that make the valuable mineral water repellent. A spinning impeller breaks injected air into fine bubbles, the treated mineral grains stick to them and ride up into a froth, and the froth overflows into a launder while waste rock stays wet and leaves as tailings.

Controls

Labels

Animation speed

Air rate (superficial gas velocity)

Air flow divided by the cell cross section.

Residence time

Step through it

Conditioned slurryFinely ground ore arrives as a slurry. Collector chemicals coat the valuable mineral so water no longer wets it.
Impeller and airAir comes down the hollow shaft and the spinning impeller shears it into small bubbles while keeping the solids suspended.
Bubbles pick up grainsWater-repellent grains cling to passing bubbles and rise. Wet waste grains sink back and leave through the tailings outlet.
Froth and launderA frother chemical keeps the bubbles stable long enough to form a thick froth that spills over the lip into the launder.

A first-order rate model

Metallurgists often describe a flotation cell like a chemical reaction: in each minute a fixed fraction of the floatable mineral is captured. That gives recovery R = 1 minus e to the power of minus k times t, where k is the rate constant and t is the time the slurry spends in the cell.

Here k rises in proportion to the air rate, a simplified stand-in for the bubble surface area flowing through the cell. Real k values depend on particle size, chemistry and bubble size, and also plateau because recovery never quite reaches 100 percent.

Try it: set the air rate to 0.5 and the time to 4 minutes, then raise the air to 2.5. Recovery climbs from under half to over 90 percent, and the bubbles rise faster in the scene.

Recovery versus grade

Pushing recovery too hard drags along waste particles trapped in the froth, lowering the grade of the concentrate. Plants run banks of cells in series, with rougher, scavenger and cleaner stages, to balance the two.

Sources

AMIT 145: Lesson 5 Froth FlotationUniversity of Alaska Fairbanks, Mill Operations Training
Representation of Kinetics Models in Batch Flotation as Distributed First-Order ReactionsMinerals (MDPI, open access)

How to cite this model

Avid Solutions International. (2026, November 11). How froth flotation lifts out minerals [Interactive 3D model]. Avid Field Lab. https://avidsolutionsintl.com/explore/froth-flotation

Last updated November 11, 2026

Keep exploring

Mining & EarthHow a ball mill grinds ore Mining & EarthHow a cone crusher makes gravel Mining & EarthHow heap leaching pulls metal from ore Mining & EarthHow a hydrocyclone splits fine from coarse