Froth flotation is a mineral-concentration process that separates sulfide minerals (and some oxides) from finely ground ore based on differences in surface chemistry. Specific reagents make target minerals hydrophobic; air bubbles attach to them and float them to the surface where they are collected as a concentrate. Flotation is the dominant base-metal recovery method and an important step for refractory or sulfide gold ores.
How It Works
Ore is ground to liberate mineral grains (typically P80 of 75 µm). The slurry is conditioned with collectors (xanthates, dithiophosphates) that selectively coat target sulfide minerals, frothers (MIBC, pine oil) to stabilize the air-water interface, and modifiers (lime, copper sulfate) to control selectivity. Air is sparged into the flotation cell; bubbles attach to hydrophobic mineral particles and float them as a froth.
When to Use for Gold
Gold flotation is the method of choice when gold is locked in sulfide minerals (pyrite, arsenopyrite) and won't respond to direct cyanidation. The flotation concentrate is then either roasted, autoclave-leached (POX), or sold to a smelter that processes refractory concentrates.
KCA Flotation Capabilities
KCA built a 50 kg/h flotation pilot plant with thickeners for concentrate and tailings drying. We have delivered a container-mounted column-cell pilot flotation plant for a major mining company testing copper ore in South Africa, and the Tambor 200 TPD flotation plant in Guatemala. KCA lab runs flotation testwork for client refractory-gold and base-metal projects.
Limitations
Flotation is not the right answer for free-milling gold or oxide ores — for those, direct heap or agitated cyanidation is more efficient. Flotation also generates wet sulfide tailings that require special long-term management.
Have a project that involves Froth Flotation?
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