Patent ID: 8069581

Claim:
A system for purifying contaminated soil, comprising: a dryer which dries contaminated soil, separates waste gas generated during the drying from the contaminated soil, and discharges the waste gas; a pyrolysis apparatus which indirectly heats the dried contaminated soil in a hermetic condition to divide the contaminated soil into purified soil and pyrolysis gas, and separately discharges the purified soil and the pyrolysis gas; a transfer fan for forcibly transferring the discharged pyrolysis gas; a burner for oxidizing the waste gas discharged from the dryer and the pyrolysis gas forcibly transferred from the transfer fan, to heat the pyrolysis apparatus; and a cooling facility for directly spraying cooling water on the discharged purified soil to cool the purified soil, wherein the dryer comprises: a dryness checking part for measuring a moisture content of the dried contaminated soil; and a bypass through which the dried contaminated soil is discharged, and which is connected at one end thereof to the pyrolysis apparatus and is connected to the dryer so as to control a discharge direction of the contaminated soil, in which, as a result of checking a moisture content of the contaminated soil discharged through the dryer using the dryness checking part, another end of the bypass is closed while the one end of the bypass is opened when the checked moisture content is determined to be less than a specified value, and the one end of the bypass is closed while the other end of the bypass is opened when the checked moisture content is determined to be greater than the specified value, thus controlling the discharge direction of the contaminated soil.