Experimental data on solid particle velocities were obtained from a 5 cm i.d. Schildknecht-type column by using model systems. The variables tested were the helix angular speed, the solid concentration, the particle diameter, and the viscosity of the supporting fluid. Two transport regimes were observed depending on the ratio Vx/Vn, where Vx is the particle free-settling velocity and Vn the apparent downward helix velocity. For both regimes, data were correlated by using a velocity equation. For Vx > l/n, the experimental data fit a correlation reported in the literature if suitable frictional coefficients are inserted. For l/t < l/n, an empirical correlation has been developed to describe quantitatively the crystals axial velocity which takes into account the helix speed and the system's physical and transport properties.