Decontaminating soil by treatment after excavation - by using drying and desorption stages pt. of steam used for drying serving also as desorption medium

摘要

The soil is excavated and passed through a number of treatment stages. The soil is dried in a first treatment stage (3) and a desorption medium is passed through the dried soil in a second treatment stage (20). A hot rinsing gas, superheated steam or an inert gas, may be used as desorption medium. The soil may be dried in the first treatment stage by passing a hot gas through it, or by using a hot gas in an indirect heating system. The hot gas from the first stage is used as desorption medium in the second stage and after separation of contaminants and water is returned to the first stage. The soil is held at a temperature of about 100 to 300 degrees C in both the first and second treatment stages. USE/ADVANTAGE - Used for treating contaminated soils. The proposed method is fast and effective and does not require the soil to be heated to high temps. so that little chemical change takes place in the soil or in the contaminants.