An innovative way to upgrade heavy crude oils is the use of ultradispersed catalysts; however, an adequate mathematical expression that describes the mass transfer on this process is still missing. This paper studies the separation and suspension of ultradispersed particles based on their motion through diverse viscous media enclosed in horizontal cylindrical channels. A time-dependent, three-dimensional convective-dispersive model which simulates the transient deposition and suspension of these particles immersed in viscous media inside a horizontal cylinder was developed and solved. This model was also experimentally validated, and its results unveiled the particle and fluid media properties that are necessary to control particle deposition. The experiments were performed using Fe2O3 particles (average sizes of 198 nm) immersed in water-glycerol mixtures with different densities and viscosities subject to different fluid velocities. The effect of the fluid medium properties, the initial particle concentration, and fluid velocity on the dispersion coefficient was also studied.