In the preheat zone, water and volatile organic compounds are vaporized. Hot solids and heavy hydrocarbons pass through a proprietary sand seal to the retort zone. After cyclones remove dust from the gases, they are cooled, and condensed oil and water are separated into various fractions. Soil passes through a third sand seal to the combustion zone. Some of the soil is recycled to the retort zone through the second sand seal, the remainder enters the cooling zone.
Soil exiting the cooling zone is quenched with water and conveyed to a storage pile.
The system treats petroleum hydrocarbons, halogenated hydrocarbons, polynuclear aromatic hydrocarbons, and volatile metals. No leachable products were produced and volatile or semi-volatile organics were not detected in the treated soils. A PCB destruction and removal efficiency of 99 percent was achieved at Waukegan.