Site Demonstration of the Retech Plasma Centrifugal Furnace: The Use of Plasma to Vitrify Contaminated Soil

Abstract

The Plasma Centrifugal Furnace (PCF) developed by Retech Inc. of Ukiah, California was demonstrated under the EPA’s Superfund Innovative Technology Evaluation (SITE) Program in July 1991 at the U.S. Department of Energy’s Magnetohydrodynamics Component Development and Integration Facility (CDIF) in Butte, Montana. The PCF was designed to function as a vitrification technology in that plasma energy was used to melt contaminated soil. On cooling, the treated soil formed a glasslike matrix which effectively immobilized metal contamination. During vitrification, organic contamination in the soil was driven off and thermally destroyed. The treated waste was never exposed to the extremely high temperatures present in the center of plasma plumes. Rather, it experienced temperatures of approximately 2000°F which is similar to conventional incineration temperatures. Nevertheless, 99.99percent Destruction and Removal Efficiencies (DREs) were achieved and the vitrified soil passed the TCLP test.

One can conclude from this demonstration that using plasma-based waste treatment systems to vitrify soil is possible and of some value in the remediation of Superfund sites. As a means of vitrification, plasma may be competitive with other means of vitrification such as direct electric heating and slagging combustion. Plasma-based waste treatment systems provide an option for treating Superfund sites contaminated with both organic chemicals and metals. This paper discusses the background of the development of plasma systems, summarizes the results of the SITE demonstration of the PCF and compares its performance to that of other vitrification technologies.