TABLE OF CONTENTS In any flotation system, the use of the collector alone is very rare and may be sufficient for selective flotation if the minerals differ sharply in their flotation properties. In practice, such a case does not exist and these differences in flotation properties are achieved by the use of regulating reagents. The regulating reagents are used for increasing selectivity and/or recovery of floated minerals.
Regulating reagents are also capable of controlling the adsorption of collectors on mineral surfaces. Therefore, the introduction of regulating reagents in the practice of flotation enables flotation separation of complex sulfide ores, silicates, oxides, calcium-containing minerals, etc.
The regulating reagents, under different conditions, can act as activator, depressant, dis-persant, etc. For this reason, classification of the regulating reagents into different groups according to their interaction cannot be made and would be grossly inappropriate.
On a number of occasions, in the previous chapters, the importance of understanding the surface chemistry and action of collectors has been stressed. However, understanding the action of regulating reagents is a different matter. Perhaps the biggest weakness of the mineral flotation science is the lack of understanding of the action of regulating reagents. It is safe to say that the importance of these reagents in mineral flotation is grossly underestimated. Some of the problems can best be illustrated through several examples from practice. Sodium cyanide is a classic example of a regulating reagent that is widely used as a depressant in sulfide flotation, i.e. for depression of iron sulfides (e.g.
