Fine grained dolomite was granulated in a lab. disc granulator after addn. of distd. H2O, optionally with a dye for 6-48 mm to study the nuclei mass transfer. The water was delivered to the tumbling bed at a const. flow rate as nozzle-generated droplets with a size of approx. 5 mm. The sieve anal., spectrophotometric studies and mass balance were used to det. changes in the mass of dye-contg. nuclei and mass transfers.