Flotation agents: Collectors, frothers, or modifiers

The collector is the heart of the flotation process. It is the reagent which produces the hydrophobic film on the mineral particle.

Most collectors in current use are heteropolar. That is, they contain both a polar (charged) and a non-polar (uncharged) group. When attached to the mineral particle, such collector molecules are oriented so the non-polar or hydrocarbon group is extended outward. This results in the formation of a hydrophobic hydrocarbon film on the mineral surface.

Figure 1, illustrates air bubble / mineral surface contact both with and without a collector. With no collector, the air bubble makes only negligible contact with a mineral surface and therefore flotation is impossible. When a collector is used, a 60° angle contact is obtained, and a favorable condition for flotation exists.

In early flotation practice, a hydrocarbon film was obtained by the physical adsorption of a neutral oil on the mineral. The introduction of more selective on the mineral. The introduction of more selective xanthates and other heteropolar compounds in the early 1920’s rapidly made oil flotation obsolete. Therefore, this discussion of collector action is limited to presently used “chemical” collectors.