Thermal granulation of U3O8 powder using a rotary voloxidizer

The thermal granulation of U3O8 powder using a rotary voloxidizer was investigated in terms of the initial particle bed motion such as slumping and rolling, thermal pretreatment (voloxidation) temperature and time, and the rotational speed in slumping motion. The granules, particles of larger than 1 mm, were obtained directly from fine particles of U3O8 by only heating and rotating the reaction chamber. With respect to the initial particle bed motion, the yield of granules of above 1 mm in slumping motion was higher than that in rolling motion. A rolling motion was changed into a slumping motion with high slumping frequency by formation of granules from fine particles. Granule yield significantly increased with an increase in the thermal pretreatment temperature and time of up to 10 h. As the rotational speed of the reaction chamber in the case of the initial particle bed showing a slumping motion increased, the granule yield increased from 81.5% to 88.7%. However, a rotational speed of 2 rpm provided an effective density, crushing strength, and circularity of the granules. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.