Abstract: The contaminants in the material are volatilized in a drum having a burner. The volatilized contaminants are separated from material particulates in a separator and are preheated in a heat exchanger for flow into an afterburner. The afterburner burns the volatilized contaminants to provide a clean exhaust gas to the hot side of the heat exchanger, the clean exhaust gas being cooled in the heat exchanger and exhausted to a stack. To control the exhaust temperature of the afterburner to the heat exchanger, a bypass conduit from the afterburner flows exhaust gases through a water seal valve bypassing the heat exchanger. The level of water in the valve can be adjusted to modulate the flow of hot clean exhaust gases from the afterburner bypassing the heat exchanger, thereby to control the temperature at the inlet of the heat exchanger.

Abstract: A materials-handling plant is convertible for producing asphalt by either batch or continuous drum mix processes or remediating soil. Common to each process is a rotary drum and burner system for heating the materials, a primary separator and a baghouse for separating particulate matter from exhaust gas streams. For asphalt production by a batch process, aggregate is dried in the drying section of the drum and discharged for combination with asphalt in a batch tower. In the continuous drum mixer mode of asphalt production, dried aggregate is discharged into a drum mixing section for mixing with asphalt and recycle asphalt and conveyed to a storage silo. In both cases, particulate dust is separated from the exhaust gas stream and combined with the resulting asphalt product. For soil remediation, the contaminants in the soil are volatilized in the drum by contact with the hot gases of combustion. Dust particles in the exhaust gas stream are separated and contaminants thereon volatilized in the baghouse.

Abstract: The remediation apparatus includes a pair of heating units, e.g., rotary drum dryers, each having a contaminated material inlet and a burner at opposite ends whereby the contaminated material and hot gases of combustion are in heat exchange, preferably counterflow relation. Material-bearing hydrocarbon contaminants are heated in the first drum to volatilize the low boiling fraction. The soil is conveyed to the second drum and heated to a higher temperature to volatilize the intermediate and high boiling fractions. The volatilized contaminants from the second drum are returned to the burner of the first drum for at least partial oxidation and reduction of the higher fractions to lower fractions. The dust and gases exiting the first drum flow to a baghouse for separation into dust and volatilized contaminants. The dust is returned to the soil. The volatilized contaminants are further eliminated, e.g., by oxidation.

Abstract: A soil remediation unit includes a counterflow drum for burning off volatile hydrocarbons and delivery to a cooler drum. Particulate-laden gases of combustion flow through a separator wherein the particle stream is delivered to the cooler drum and the gas stream delivered to a heat exchanger. The gas stream flows to a thermal oxidizer, the exhaust gas from which lies in heat exchange relation with the gas from the separator. Portions of the exhaust gas are passed into the separator in counterflow relation to the particles for remediating the particles.