Electrostatic Charging and Entrainment Behaviors of Binary and Quaternary Particulate Systems in Multiphase Flows

A number of commercial fluidization processes involve particulate systems with different particle sizes and densities. During the operation of multiphase systems such as fluidized beds, electrostatic charges are generated majoritarily via triboelectric or frictional charging due to the dielectric nature of the materials. The accumulation of electrostatic charge within the system can impact the fluidization behavior of the system and in some cases can be operationally hazardous. In this study, the electrostatic charge generation and accumulation are investigated for binary and quaternary particulate systems using a faraday cup system and an on-line electrostatic probe system. Specifically, the effect of the addition of two different fine iron ores (i.e., hematite and magnetite) in a fluidized bed is studied in terms of particle-particle interactions and entrainment rates. The behaviors of different particulate systems are found to highly depend on the chemical and physical properties of particles such as size, density, hydrophobicity and even magnetism. The results suggest that the entrainment behaviors of complex particulate systems (i.e., mineral processing units) cannot simply be predicted based on particle sizes and densities.