Additional experimental data for the beginning, minimum and complete fluidization rates for binary and ternary mixtures of sand, diatomite and urea particles have been provided. The authors own experimental data and some more recent ones due to other authors concerning these fluidization rates can reasonably accurately be correlated by a Ergun type equation with constants suggested by Vaid and Sen Gupta or by Wen and Yu if the bed parameters are appropriately calculated. The validity of some other relationships, include those involving bed porosities, is checked.