How did flotation make previously low-value ore mixtures useful sources of metals?

Flotation revolutionized mineral processing by enabling the recovery of fine mineral particles that were previously discarded as waste in gravity concentration plants.1

The process works by exploiting the differences in the surface chemistry of minerals. By adding specific chemical reagents, metallurgists can selectively alter the surface of target minerals to make them hydrophobic (water-repelling), while unwanted gangue remains hydrophilic (water-attracting). When air is bubbled through the ore slurry, the hydrophobic mineral particles attach to the bubbles and rise to the surface as a froth, which is then skimmed off and collected.123

This technology transformed complex, intergrown ore mixtures—such as those containing copper, lead, and zinc—into valuable resources. Unlike older methods like gravity or magnetic separation, flotation allows for the precise, separate concentration of these minerals, making the extraction of metals from previously low-value or difficult-to-process ores both feasible and economically viable.12