A feed charging device comprises a holding vessel having an interior chamber for holding a reserve of a solid particulate feed material in a fluidized state, wherein the feed material is held in said fluidized state in a lower zone of the interior chamber. The feed material is supplied to the interior chamber through at least one outlet opening, and is discharged from the interior chamber through at least one outlet opening. The at least one outlet opening is in flow communication with the lower zone of the interior chamber. A gas supply means supplies a fluidizing gas to the lower zone of the interior chamber, and an outlet conduit in flow communication with the at least one outlet opening receives said feed material discharged from the interior chamber.