Microwave drying characteristics and kinetics of hematite pellets

Microwave drying characteristics and kinetics of hematite pellets were investigated based on evaluation of the effects of initial mass, microwave power and pellet size during the drying process. The results showed the average drying rate increased with initial mass from 50 g to 80 g and microwave power from 600 W to 1000 W. However, it decreased with increasing pellet size from 10–12 mm to 14–16 mm. The process was successively controlled by external diffusion, internal diffusion, and chemical reaction. The Verma model was the most suitable kinetic model for describing the process. The effective diffusion coefficient of moisture ranged from 6.61 × 10−7 m2/s to 9.98 × 10−7 m2/s. The activation energy for the microwave drying process was only 2.83 W/g. [Display omitted] •Microwave energy was used for drying of hematite pellets.•The kinetics of microwave drying of hematite pellets was investigated.•The drying process was successively controlled by external diffusion, internal diffusion, and chemical reaction.•The Verma kinetic model best fit the microwave drying process.•The activation energy for the drying process was much lower than that for the hot air drying process.