Fluidized bed of fine grains (aerosuspension) is known to be used to separate a mixture of particles of different size and composition in gravity concentration of minerals.

The limits of the applicability of the concept of viscosity. In molecular physics, it is shown that the phenomena of diffusion, thermal conductivity, and internal friction in gases are based on a single mechanism - the transfer of mass, energy, and amount of motion from one gas layer to another by chaotically moving molecules. This commonality of the mechanism is manifested in the presence of a connection and mutual proportionality of the coefficients of diffusion, thermal conductivity and internal friction - viscosity...

Free fall of spherical particles in a viscous fluid has been studied by many researchers in connection with mineral processing, chemical technology, metallurgy, etc. By changing the diameters of balls, density and viscosity of the fluid, it was possible to trace the motion of particles in the region of small and large values of the Reynolds and Archimedes criteria, i.e. in laminar, transitional and turbulent regimes.

In a number of branches of engineering - in gravitational concentration of minerals, some processes of chemical technology and others, we meet with the constricted motion of bodies in a medium with resistance. At constricted motion conditions of streamline and resistance forces depend on such factors as body dimensions, fluid properties, proximity of neighboring bodies or vessel walls, etc.

As follows from the theoretical analysis of the process of motion of a ball in a viscous fluid in constricted conditions, the regularity of the constricted motion of a ball along the axis of a cylindrical tube is described by the relation ...