Vanadium slag contains high contents of
vanadium and
chromium with complex and dense structures, hence microwave heating instead of conventional methods is expected to destroy the dense structure and further to improve the extraction rate of
vanadium and
chromium, and exploring its dielectric properties is the prerequisite work. Microwave absorption properties and thermal behavior of
vanadium slag were investigated. Results indicated that
vanadium slag endowed excellent microwave absorption properties, with minimum εr' value of 34.447 (F/M). Dielectric properties of
vanadium slag varied with temperature, which changing trend was matched to the three stages of microwave heating characteristics identified by heating rates. Meanwhile, the changing process of dielectric properties also corresponded to the three processes of thermogravimetric characteristics:
dehydration stage (30 °C-280 °C), oxidation decomposition of
olivine phase and normal
spinel phase (280 °C-650 °C), and oxidation decomposition of
vanadium chromium spinel (650 °C-950 °C). Moreover, the maximum dielectric constant and highest microwave heating rate of
vanadium slag both appeared at the temperature regime of 500 °C-550 °C, which was also the main temperature regime for oxidation decomposition of
olivine phase and normal
spinel phase in
vanadium slag, demonstrating the appropriate process temperature for microwave heating technology to recycle
vanadium slag.