The shaft furnace plays a very important role in the quantity and quality indexes of the COREX process. However, research on burden distribution in the COREX shaft furnace is still immature and in need of further development and improvement. For instance, only a single ring charging process rather than multiple rings or a burden matrix process has been simulated for the shaft furnace in practical operation. Therefore, a three dimensional model of the upper part of COREX shaft furnace is developed in the present study. The model simulates the charging process with multiple rings and is then used to investigate the effects of different bottom base shapes on the burden profiles and radial size distributions. Results show that the last rings (the inner rings) in the burden matrix needs be carefully chosen, especially for the middle mode. The bottom base shape affects the burden size distribution a great deal but the surface burden profile very little at a fixed burden matrix. A bottom base of M shape is strongly recommended to obtain a uniform burden size distribution. The burden matrix and bottom base shape need to be well matched in order to obtain desired gas distributions. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.