Abstract:The microwave drying of ilmenite was investigated. The effects of power levels and sample mass on drying characteristics of moisture content, drying rate, moisture ratio were studied, with microwave power ranging from 119 W to 700 W and sample mass from 5 g to 25 g. The drying processes were completed within 2−8 min at different conditions. The moisture content and drying rates are found to be dramatically affected by microwave power density. For all drying processes the prior microwave absorption of moisture produces an accelerating peak on the drying rate curves in the initial stage. For the sample mass of 25 g and power of 385 W, the drying kinetics were studied. The experimental results fit better to the Henderson−Pabis index model rather than the Page’s semi-empirical model; the drying rate constant k is increased with the increase of microwave power and decrease of sample mass.

Key words: ilmenite; microwave drying; moisture content; drying rate; moisture ratio; kinetics