The article presents the results of research of hydrodynamics of flow of the gas-suspension of conversion lime carbonate in a tube-dryer. For the first time equations for determining the speed and concentration of lime carbonate along the length of the tube-dryer at different air velocities and feed concentrations are received. The research results can be used to design pipes-dryers for large-tonnage productions of conversion of calcium carbonate. Experiments of research of hydrodynamics of the gas-suspension of conversion lime carbonate were carried out on the tube-dryer with an internal diameter to 0.069 m, length 4.8 m. Along the axis of the pipe on the rod vertically mounted discs, the first disc below the auger to 0.6 m, the second - above the auger to 0.7 m and further 1 m, total 5 disks.