Abstract

A method for treating contaminated solids such as contaminated soil or sludge includes feeding the solids into a preheater and pneumatically conveying the solids through the preheater by preheated primary air into and through an oxidation chamber by cocurrent flow. Secondary air is directed into the oxidation chamber through a plurality of perforations in the wall of the oxidation chamber to combine with and sustain the fluidized state of the solid-gas mixture. The primary air is preferably produced by an air blower which blows the air through a preheater to produce hot air. The temperature of the fluidized bed is controlled by the temperature of the primary air. The temperature should be hot enough that the lighter hydrocarbons spontaneously ignite in the oxidation chamber. The exothermic combustion causes the remaining organic material present in the contaminated solids to then vaporize and burn. The product of this process, termed flash oxidation, is a mixture of treated solids, excess hot gas and gaseous and solid oxidation products. This mixture is separated such as by one or more cyclone separators or a baghouse to produce treated solids and process gas in a once-through process with essentially no recycle of solids.