Effect of temperature on flow properties of magnetofluidized beds at low consolidations

Abstract

In this work we investigate the fluidization behavior and mechanical properties of granular beds of fine magnetite beads as affected by an increase of temperature and the application of a magnetic field. In the range of temperatures tested (up to 200°C) the cohesiveness of the bed is decreased with temperature whereas it is enhanced by the magnetic field as revealed by measurements of the gas velocity at the fluid to solid (jamming) transition and the tensile yield stress of the bed settled under low consolidation stresses. The opposed effects of temperature and the magnetic field are independent in the range of temperatures tested. The increase of cohesiveness induced by the magnetic field, as reported in previous studies, can be explained from the enhancement of interparticle attractive forces due to particle magnetization. On the other hand, the observed decrease of cohesiveness with temperature, which can be of great relevance in many practical applications, is in contrast with reported results from previous works using other materials. This suggests that the effect of temperature on the cohesiveness of granular materials is material dependent. The physical mechanism by which interparticle attractive forces are affected by an increase of temperature remains as a relevant subject for future work.