Gas powder flow in a slot type packed bed is experimentally studied in order to understand the flow and accumulation behaviour of powder in systems like an ironmaking blast furnace (BF). A variety of variables including gas flow rate, powder flow rate and packing properties are considered. It is found that a clear and stable accumulation region, in which the voids among packed particles are fully filled with powder, can form in the low gas-powder velocity zone at the bottom of the bed. The accumulation region is stable and shows strong hysteresis. The distribution of softening-melting layers in the blast furnace known as the cohesive zone (CZ) is modelled by inserting solid blocks into the bed. The results indicate that the inverse-V cohesive zone shape leads to low powder accumulation within the CZ and at the corner of the bed. (C) 2004 Elsevier B.V. All rights reserved.