The direct utilization of fine iron ore concentrate in fluidized beds is of significance but has the problem of defluidization during operation. In this study, we have made a comparison of a conical fluidized bed and a cylindrical fluidized bed for the direct reduction process. The results showed that the conical fluidized bed was more versatile than the cylindrical fluidized bed in treating the fine iron ore concentrate. In the conical fluidized bed, with a high superficial gas velocity, defluidization was successfully inhibited without adding inert materials or causing elutriation issues. Simultaneously, the reduction efficiency was considerably improved and the obtained iron agglomerates exhibited a high metallization degree. This work also proposes a fluidization regime diagram for the conical fluidized bed at the temperature range from 650 to 800 degrees C According to the fluidization regime diagram, the conical fluidized bed is able to considerably expand the operational temperature range for the direct reduction process. These results demonstrate that the conical fluidized bed is a clean, efficient alternative means for intensifying the direct reduction process. (C) 2017 Elsevier B.V. All rights reserved.