Disperse powder material layer vibrational fluidization state modeling with a view to describe dry concentration processes

The paper presents a description of bulk material dynamics model in vibrational fluidization state. The theory of so-termed quasi-aggregative states of loose material media under vibration actions of varying level was used as a basis. The presented model of flat-layer granular gas was developed with a view to investigate separation processes without using water as dispersion medium. Application of approaches, based on analytical representations of free-flowing bulk materials, provides a number of advantages over modeling that involves popular methods of molecular dynamics or discrete elements. The advantages include highspeed and the possibility to explain observed phenomena, in addition to simple appraisal of microscopic features, which is especially important in development of principally new devices. This paper deals with a flat layer of free-flowing bulk material in quasi-aggregative state of granular gas, which corresponds to the case of high-level vibration and relatively small layer thickness. For the material in question, the equations of state, balance of forces in barometric form and energy balance are written. Granular temperature is introduced in this connection as average kinetic energy of particles. The system in question must satisfy the conditions of conservation of quantity of particles and energy flux degradation at a distance from vibrating plane. On the basis of the above theory, the analytical estimation of vibrational fluidization material layer effective thickness (containing 2/3 of all particles) is proposed. The practicality of the model in question has been checked in computations of a number of new sizing devices. The model may also serve as a basis for development of the methods of theoretical description and optimization of many dry concentration processes with disperse powder materials in vibrational fluidization state.