dN/dt – flotation rate,

a – centrifugal acceleration acting on particle-bubble aggregate in a vortex of liquid,

Bo´ – Bond’s number,

cb – rigidity of bubble surface (cb = 1 for rigid uneven surface, cb < 1 for movable smooth surface),

Cb – bubble concentration in pulp (number of bubbles in 1cm3 of pulp),

E – efficiency of attachment of particles to bubble surface (number of attached particles divided by the number of particles colliding with considered bubble),

E1–energy barrier for adhesion of bubble and particle,

Ek – kinetic energy of collision of bubble with particle,

Ek´ – kinetic energy of detachment of particle and bubble (calculated from the French–Wilson Eq.),

g – acceleration due to gravity,

hkryt – critical film thickness on surface of particle,

k – rate constant of flotation,

Nb – number of bubbles in flotation cell at a considered time,

Np – number of particles subjected to flotation at a considered time,

Pa – probability of adhesion of particles to a bubble,

Pd – probability of detachment of particles from a bubble (Pd = 1 – Pstab),

Pstab – probability of stability of particles-bubble aggregate,

Ptpc–probability of formation of particle-bubble-water contact,

Q – flow of air in flotation machine, m3/s,

Rp – particle radius,

Rb – bubble radius,

Rc – radius of the stream enabling collision of particle with bubble,

RF – size of thin film between particle and bubble during collision,

Re – Reynolds number,

S – cross section area of flotation machine, m2,

Sb – area of bubbles leaving flotation cell per time unit and per cross section area ot the cell,

V – rate of ascending bubble, m/s,

Vb –surface velocity of aeration defined as volume rate of aeration normalized per cross section of the flotation column,

U – velocity of particles in relation to velocity of bubble in the pulp,

Z – number of particle collisions per unit time,

– surface tension of aqueous solution,

– quantity characterizing efficiency of collision between particles and bubbles,

* – dissipation energy in flotation cell,

– effective density of particle in water,

– dynamic viscosity,

– kinematical viscosity,

– pulp density,

p – particle density,

– contact angle,

A – advancing contact angle,

v – life time of liquid vortex in flotation cell which destroys the particle–bubble aggregate,

tpc – time needed to form permanent three-phase solid-gas-liquid contact,

c – collision time of bubble and particle,

i – induction time (time of removing liquid film from particle and forming attachment),

min – minimal time of contact,

= 3.14,

* = 180 – /2.