Stochastic modeling of particle coating

Dry coating of powders, in forming a layer, consists of fine particles of o ne component onto the surface of coarser particles of another component. In the process, fine particles are transferred among colliding coarse particl es (carriers) until a steady-state distribution of fines on the carriers su rface is attained. A stochastic model was developed for the kinetics of fin es transfer based on a birth-death population balance including theoretical ly-derived one-step transition probabilities. First, the population balance equation is solved under steady-state conditions leading to the result tha t, at equilibrium, the number of fines per carrier follows a Bernoulli dist ribution. Based on the obtained equilibrium distribution, an approximate tr ansient solution proposed agrees fairly well with the numerical solution of the birth-death equation. Model predictions were compared qualitatively wi th earlier experimental results.