WASHING METHOD AND WASHING APPARATUS OF CONTAMINATED SOIL

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PROBLEM TO BE SOLVED : To provide a washing method and a washing apparatus of contaminated soil stripping and separating contaminants firmly adhering on surface of earth and sand, and improving quality of washed soil. SOLUTION : In this washing method of contaminated soil, contaminated soil containing toxic contaminants is washed and separated into washed soil and condensed residue containing condensed contaminants, the washed soil is recycled, and the condensed residue is recovered for treatment. The method comprises processes for : adding water to the contaminated soil, classifying it by wet screening to separate gravel and coarse sand to form slurry earth and sand; adding a dispersant to the slurry earth and sand, mixing and agitating to strip the contaminants from the surface of the earth and sand; treating the slurry earth and sand by a hydrocyclone to classify into sand/fine sand and fine particles containing the contaminants; separating metal contaminants by gravity type separation of the classified sand/fine sand; obtaining washed earth and sand through dewatering process of the sand/fine sand and separating separated fine particles into settled sludge and water by coagulation settling; dewatering the settled sludge and separating into the condensed residue and water, to obtain the condensed residue. COPYRIGHT : (C)2006, JPO&NCIPI