Simulation of diffusional mixing of particulate solids by Monte Carlo techniques

Abstract A model for the simulation of the process of mixing ideal particles in an end-loaded barrel mixer is presented. The only mechanism operating in such a mixer is micromixing by diffusion, which can be considered as a random walk process. The probability distributions which govern particle movement have been defined with respect to a mixer which has been conceptually divided into sections of equal width, by passing planes through the mixer perpendicular to its axis. Observations of the movement of an individual particle for various load-speed combinations in a laboratory mixer were used to quantify these probability distributions experimentally. Relationships for the diffusion coefficient were derived from Fick's Second Law. Further, the mixing of these same particles was determined experimentally, and diffusion coefficients obtained from the simulation and from the actual mixing correlate very well. Mixing within the system used can accurately be simulated by the use of Monte Carlo techniques and the digital computer.