Slurry inletGround ore mixed with water comes in here.
Air inletAir is fed in here. The impeller breaks it into small bubbles.
In the tank 5
ImpellerIt spins and stirs the pulp. It also breaks the air into small bubbles.
PulpIt is finely ground ore stirred into water. Another name for it is slurry.
Air bubblesThey rise through the pulp to the surface. Water-repellent grains stick to them.
Mineral particlesThey are grains of the wanted mineral, made water-repellent. They ride the bubbles up to the froth.
GangueThey are grains of worthless rock from the ore. They do not stick to the bubbles.
What comes out 3
FrothBubbles loaded with mineral collect here. The layer floats on top of the pulp.
ConcentrateIt is froth that has left the tank. It carries most of the wanted mineral.
Tailings outletWhat did not float leaves here. It is mostly gangue and water.
How this list was compiled: Every name and fact checked on 2026-10-01, a name kept only where two independent sources use it. (1) Wikipedia, text only: Froth flotation, https://en.wikipedia.org/wiki/Froth_flotation (minerals are separated from gangue by differences in how well water wets them; ground ore in water, called pulp or slurry, enters the cell; air is passed down a vertical impeller, which breaks it into small bubbles; water-repellent particles attach to the bubbles; the mineral concentrate froth is taken off the top; what does not float is the tailings; collectors and frothers are added; mechanical cells stir and add air with a mechanism at the bottom of the tank). (2) University of Arizona, Superfund Research Center, Copper Mining and Processing: Processing Copper Ores, https://superfund.arizona.edu/resources/learning-modules-english/copper-mining-and-processing/processing-copper-ores : crushed ore and liquid make a slurry of copper minerals and worthless rock, called gangue; collectors make the copper particles water-repellent; air is blown into the tank to make bubbles, which rise and carry the copper particles along; the froth at the top is skimmed off; the gangue sinks and is removed as tailings. (3) US Department of Energy, Energy and Environmental Profile of the U.S. Mining Industry, chapter 5, Copper, https://www.energy.gov/sites/prod/files/2013/11/f4/copper.pdf : the rock and water slurry is treated with air and with frothing and collector agents in a flotation tank; the copper value rises to the surface as froth; the material that remains, the gangue, is discharged as tailings; the product is the concentrate. (4) US Environmental Protection Agency, Technical Resource Document, Extraction and Beneficiation of Ores and Minerals, volume 1, Lead-Zinc (EPA 530-R-94-011), pages 1-16 to 1-18, https://archive.epa.gov/epawaste/nonhaz/industrial/special/web/pdf/leadzinc.pdf : pulp, a suspension of milled ore and flotation reagents, is fed to the flotation cells; small air bubbles are added by an air blower or by the action of a submerged rotor or impeller; collectors make the particles cling to the bubbles and frothers stabilize the bubbles; the valuable material is skimmed from the top and what does not float falls as tails; the froth of the cleaner cells gives the concentrate. The sister volume on copper, https://archive.epa.gov/epawaste/nonhaz/industrial/special/web/pdf/copper1a.pdf : air is pumped through the agitated slurry, and the froth overflows into a trough for collection. Impeller and Pulp are the words of sources 1 and 4; the other eight names stand in source 1 and in source 2 or 3. Licence: own work
The drawing: Drawn for this site on 2026-10-01 from plain geometry; nothing traced. Licence: own work
How it works
A flotation cell separates a wanted mineral from the rest of an ore. Ground ore is stirred into water, air is bubbled through, and the mineral rides the bubbles into a froth. This froth flotation cell is cut through.
Read the full guide
What goes in
Ore is ground fine and mixed with water to make pulp. Chemicals called collectors are added, which make the grains of the wanted mineral water-repellent. Air is fed in, and the impeller stirs the pulp and breaks the air into small bubbles.
What comes out
The water-repellent grains stick to the bubbles and rise into the froth, which spills over as the concentrate. The waste rock, called gangue, stays in the pulp and leaves by the tailings outlet.
A frother is added as well, so the bubbles last long enough to carry the mineral over the edge.
Questions and answers
What is froth flotation?
A way of separating a wanted mineral from the waste rock in an ore. Ground ore is mixed with water and air is bubbled through; the mineral sticks to the bubbles and floats off in a froth.
How does a flotation cell work?
An impeller stirs the pulp and fills it with small air bubbles. Water-repellent mineral grains ride the bubbles up into the froth, which overflows as concentrate. The rest leaves at the bottom as tailings.
Why do some particles float and others stay behind?
A collector chemical coats the wanted mineral and makes it water-repellent, so it clings to air bubbles. The gangue stays wet, does not cling, and remains in the pulp.
What is gangue?
The worthless rock that is mixed with the valuable minerals in an ore. In a flotation cell it stays in the pulp and is carried out with the tailings.