The collision rates for fine particles (50 - 80 μm) can be accurately modeled, but there is no current theory that accurately models bubble-particle collision for particles as large as 300 μm, which are commonly used in flotation processes.
For fine particles, Stokes law underestimates collision probability while the potential equation based on surface charge overestimates collision probability so an intermediate equation is used.
It is important to know the collision rates in the system since this step precedes the adsorption where a three phase system is formed.