Particle liberation plays an important role in flotation processes as demonstrated by studies on detachment of particles during bubble coalescence, or by comparison of kinetic parameters for liberated or locked particles. On the other hand, the phenomena occurring in the froth layer in columns, or in mechanical cells working with a thick froth layer enhance selectivity. This has direct consequences on circuit design both in the general flowsheets, such as the relative position of grinding, or regrinding and flotation stages, and in the choice of flotation equipment. The scale of the operation also plays an important role. In flee flotation, as in Ca F-2 flotation, obtaining high-grade concentrates may require mechanical agitation to eliminate impurities interlocked and trapped within the flocs.