The teetered bed separator (TBS) is a gravity concentration device based on the principle of hindered settling velocity, which has been widely applied for the density separation of coarse coal particles. The influences of the teeter water velocity on the density separation of coarse coal particles were investigated based on the slip velocity model and the experimental results. The ash content of clean coal increased as the teeter water velocity decreased initially and increased afterwards according to the relationship between teeter water and minimum fluidization velocity. It was observed that the foreign slime had an effect on the separation of coarse particles, while the effect of the foreign slime was not as significant as that of the teeter water velocity. (C) 2017 Published by Elsevier B.V.