Experimental and simulation studies on the role of fluid velocity during particle separation in a liquid–solid fluidized bed

The fluidization technique has been in use for particulate material processing operations for many years. It has been widely believed that the ratio of size and density of the particulate components controls the separation efficiency. In this paper, it is demonstrated that fluid velocity during fluidization could assume an overriding significance when an improvement in separation efficiency is required. This was at first experimentally established by analyzing simpler particulate systems, and later a simulation scheme was adopted to study a wider range of particulate systems. The numerical scheme known as the discrete element method (DEM), that incorporates both the solid- and hydro-dynamic components of the interactive forces, served as an important tool in understanding the separation behavior of binary particulate systems in fluidized beds. It has been established that mere fluidization does not necessarily guarantee an optimal separation, especially when the particles differ widely in density and size.