18 described in connection with fig2 and 3 it will be appreciated that the facing surfaces of the shield 40 and the ring 41 are smooth rather than patterned as in the case of the facing surfaces of the rings 14 and 15 of the first embodiment a nozzle 35 is provided similar to the nozzle 35 described in connection with fig2 and 3 by the time the moving mass of coal and ash particles reaches the branch 44 between the weir 43 and the valve 42 the dense ash particles are firmly following the surface of the ring 41 and displacing the less dense clean coal to an upper stratum at the branch 45 the coal passes over the weir 43 no peptizing having taken place while the more dense mineral ash particles bank up against the weir 43 the unbalanced forces resulting from the bank up move the ash material out through the loop 42 a and the exit leg of the valve 42 the curve of the loop 42 a of through the valve 42 is in the same direction as the flow of less dense particles liquid from the nozzle 35 injected into the loop 42 a maintains free movement of solids through the loop referring.