Vertical column hydroclassification of metal-contaminated soils

The purpose of this work was to reduce soil volumes requiring aggressive tr eatment. A second purpose was to determine differences in separation due to distinct forms of the metal contamination and soil texture. The objectives were to apply hydroclassification and find mass and metal-contaminant dist ribution of four soils contaminated with heavy metals from firing ranges, a small arms incinerator, and an electroplating operation. The soils were sl urried in water, sieved, and exposed to upward flowing water to separate th e soil particles into four nominal size ranges. The popping furnace soil ex hibited substantial lead among all particle size fractions. The firing rang e soils exhibited bimodal distributions. The electroplating soil exhibited a strong concentration of metals toward the < 63 mu m fraction. Attrition s crubbing moderately improved the enrichment of metals in several fractions. Extraction revealed the lead and chromium in the electroplating soil to be relatively immobile. These results suggest metal distributions are influen ced by the different mechanisms of introduction into the soil. They also he lp to predict performance of processing options such as sieving hydroclassi fication and attrition scrubbing. (C) 1999 Elsevier Science B.V. All rights reserved.