Artificial waste was used to simulate agglomeration/defluidization in a fluidized bed and to examine the heavy-metal distribution in bottom ash for various bed-material particle-size distributions (narrow, flat, and Gaussian). Heavy-metal concentration in most particles increased with Na addition, and the largest (>1.000 mm)- and smallest (<0.500 mm)-particle-size fractions had the highest metal concentrations. Additionally, Cr had the highest retention rate within the bed particles, followed by Pb and Cd. Comparison of the heavy-metal concentrations and retention rates for different particle-size distributions showed that the total retention rates were higher for narrow and Gaussian distributions than for the flat distribution. (c) 2012 Elsevier B.V. All rights reserved.