Nihon Genryo Co., Ltd.

Yasuhiro Saitoh

In a method of washing contaminated particulate matter, a screw conveyor is disposed in a cleaning tank for rotation around a substantially vertical axis so that the lower part of the screw conveyor is positioned under the surface of the cleaning water and the upper part of the screw conveyor is positioned above the surface of the cleaning water. Under the surface of the water, the grains of the particulate matter are contacted with each other with sludge being interposed therebetween to remove at least a part of contamination substances from the surface of the grains of the particulate matter and to wash off the substances into the water. Above the surface of the water, the particulate matter is fluidized on the surface of the screw conveyor, thereby contacting the grains of the particulate matter with each other with a slight amount of the water including the sludge being interposed therebetween to remove at least a part of the remaining contamination substances from the surface of the grains of the particulate matter. The particulate matter, which has been raised, is allowed to fall down to the lower part of the screw conveyor through a way outside the screw conveyor.

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Kawasaki, Japan

Yasuhiro Saitoh