Experiment
3.1 Magnetite medium properties
Magnetite powder is used as fluidizing medium in air dense medium fluidized bed. Normal fluidization is difficult for
magnetite powder with size below 0.074 mm because of greater intergranular viscous forces and distributor hole plugging. The
magnetite medium of larger than 0.4 mm have bad performance with respect to minimum fluidization and minimum bubbling
velocities characteristics. In this paper, four size fractions i.e., -0.4+0.3 mm, -0.3+0.225 mm, -0.225+0.15 mm and -0.15+0.074
mm magnetite medium, are studied.
3.2 Coal sample properties
The samples of -6+3mm fine coal are obtained from northwest China. Sink and float tests have been carried out by density
ranges between 1.3 g/cm3 and 1.9 g/cm3 at 0.1 g/cm3 intervals. Mass fraction, ash content, total sulfur and calorific value are
determined for each density range, as shown in Table 1.