Theoretical and experimental studies of the classification process depending on the nature of the high-speed interaction of TiN particles in a pneumogrinder with a fluidized bed

For grinding and fractionation of submicron and nanosized powders, pneumatic methods with the use of built-in centrifugal-type separation elements of various designs are currently the most promising. In these devices, it is possible to most effectively provide the aerodynamics of the dust and gas flow in the separation zone, which allows one to control the separation boundary. In a fluidized bed apparatus, the layer extends to the rotor. The particles are affected not only by gravity and flow forces but also by the forces arising from the rotor impact on the flow. This paper considers the separation effects associated with the classification of fine powders. Experimental data on the circumferential air velocities near the rotor surface are obtained as the functions of the rotor rotation number. The high-speed interactions of solid particles in a pneumatic grinder with a fluidized bed are evaluated. Using the obtained aerodynamic experimental data, the boundary size of the separated particles is calculated. A comparison of the calculated boundary size of TiN ceramic particles with the obtained experimental data on the fractional separation of fine TiN powders based on granulometric composition measurements by laser diffraction is presented.