Abstract: An apparatus for continuously mixing dust and water for disposal of the dust, the apparatus including a vertical pipe with a removable cover at its upper end, an inlet pipe adapted to deliver dust particles into the vertical pipe, a mixing chamber closed at the upper end except for the lower end of the vertical pipe discharging thereinto, the lower end of the chamber being open and submerged in a pool of water, water inlets adjacent to the upper end of the chamber directing water tangentially over the walls of the chamber, a water inlet into the pool of water, and an overflow outlet from the pool to remove a mixture of dust and water from the apparatus. A process which includes classifying ash particles from an industrial boiler, passing the smaller particles into an enclosed zone with water washing the walls of the zone and the bottom of the zone opening underneath the level of a pool of water which overflows to discharge a mixture of water and dust for disposal.