THERMAL ENCAPSULATION OF METALS IN SUPERFUND SOILS

Superfund sites frequently contain both heavy metals and organic hazar dous waste. If not properly controlled, the metals may be changed to a more leachable form and may also be emitted to the atmosphere via the exhaust stack. This paper documents a batch kiln R&D test program to solve these metal-related problems. It was performed under the U.S. EP A's SITE (Superfund Innovative Technology Evaluation) Emerging Technol ogy Program. Allis Mineral Systems has developed the Thermal Encapsula tion Process. Metals with limits set by EPA's TCLP (Toxicity Character istic Leaching Procedure) test and BLF (boiler and industrial furnace) stack emission regulations, such as cadmium, chromium, and lead, are the initial target of this process. This process, while unproven in th ese areas, may also apply to mixed waste (EPA hazardous waste/low-leve l radioactive wastes) and may also benefit commercial hazardous waste or Superfund thermal treatment systems. The results of the SITE tests were positive: strong, durable nodules were produced with excellent cr ush strength and improved resistance to leaching. Feed preparation, pa rticularly control of moisture content, was found to be a key element in initiation of agglomeration. A good correlation was found between d ecreasing TCLP metals leachate levels and increasing crush strength.