Flotation (process) - Flotación (proceso)

Flotation is a physico-chemical process of separation of minerals or finely ground compounds, based on the surface properties of the minerals (wettability), which causes one or more minerals to stay in one phase or move to another. The surface properties can be modified at will with the help of reagents.

The flotation process is based on the hydrophilic and hydrophobic properties of minerals. It is fundamentally a phenomenon of behavior of solids in front of water

The basic principles on which the flotation process is based are the following:

  • The hydrophobicity of the mineral that allows the adherence of solid particles to air bubbles.
  • The formation of a stable foam on the surface of the water that allows the particles to remain on the surface.

Establishing these principles requires the addition of chemical reagents to the system. These flotation reagents are collectors, depressants, activators and modifiers, whose main actions are to induce and inhibit hydrophobicity of the particles and give stability to the foam formed.

Hydrophobic mineral particles have the ability to adhere to the bubble, while hydrophilic ones, such as gangue, do not adhere. The hydrophobic surface exhibits affinity for the gas phase and repels the liquid phase, while the hydrophilic surface has affinity for the liquid phase.

Industrial uses

Industrial flotation of copper sulphide minerals.

Flotation is a process widely used in the recovery of copper sulphide minerals due to their natural hydrophobicity. It is also used to clean used water with fat or oil content for reuse. There are equipments that carry out this process such as flotation cells and flotation columns; the latter have been replacing cells due to their lower operating costs.

The first flotation in Europe was developed by the Cantabrian engineer Leopoldo Bárcena Díaz de la Guerra in the Cantabrian town of Torrelavega.