Which method uses bubbles to isolate metals from a mixture?

The method that uses bubbles to isolate metals from a mixture is flotation. This process involves adding chemicals to the mixture that create a froth or foam when air is introduced, allowing certain materials—typically hydrophobic (water-repelling) particles like specific minerals—to attach to the bubbles. As the bubbles rise to the surface, they carry these particles with them, creating a frothy layer that can be skimmed off. The principle behind flotation is that different materials have varying degrees of attachment to the bubbles, enabling the separation of valuable metals from the gangue (unwanted material).

Flotation is widely used in mineral processing and metallurgy, particularly for the recovery of sulfide minerals and precious metals. It is effective in separating metals from ores that have low concentrations of the target minerals, which makes it a vital technique in the mining industry.

In contrast, other methods such as gravity separation rely on differences in density, electrostatic separation utilizes charge differences, and smelting involves heating to extract metals, none of which directly involve bubbles as a mechanism for separation.