Thermal Encapsulation of Metals in Superfund Soils

Abstract

Superfund sites frequently contain both heavy metals and organic hazardous 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. EPA's SITE (Superfund Innovative Technology Evaluation) Emerging Technology Program. Allis Mineral Systems has developed the Thermal Encapsulation Process. Metals with limits set by EPA's TCLP (Toxicity Characteristic Leaching Procedure) test and BIF (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 these areas, may also apply to mixed waste (EPA hazardous waste/low-level 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 crush strength and improved resistance to leaching. Feed preparation, IMPLICATIONSMany Superfund sites have soils contaminated with organic and heavy metal wastes. Thermal treatment of these soils destroys the organic fraction, leaving the heavy metals in the ash. An R&D project was undertaken to develop a process to simultaneously destroy organic wastes and tie up the heavy metals. This paper presents the results of this project, funded by the U.S. EPA SITE Emerging Technology Program. The technology could potentially reduce the cost of thermal treatment for combined organic/metallic waste and reduce amounts of metals leaching from the ash product.particularly control of moisture content, was found to be a key element in initiation of agglomeration. A good correlation was found between decreasing TCLP metals leachate levels and increasing crush strength.

X-ray absorption spectroscopy study of a copper-containing material after thermal treatment

“…Previous studies indicate that a major portion of heavy metals can be effectively stabilized in some inorganic sorbents including aluminosilicates and silica through a heating process at 200-1300 • C [2][3][4][5][6][7]. The sintered or/and melted materials, depending on their composition, can be recycled as component resources for the manufacture of brick, porcelain, firebrick, and ceramics.…”

“…The melting process can result in minimal leaching of heavy metals in acidic environment [2], as tested by the toxicity characteristic leaching procedure (TCLP) formulated by USEPA [8]. However, no information on heavy metal speciation was reported in previous study [2].…”

“…: +886 42 359 1368; fax: +886 42 359 6858. Thermal encapsulation process based on a melting process in a pilot plant was reported to be effective in immobilizing heavy metals in Superfund site samples, as tested in a Superfund Innovative Technology Evaluation program by US Environmental Protection Agency (USEPA) [2]. The melting process can result in minimal leaching of heavy metals in acidic environment [2], as tested by the toxicity characteristic leaching procedure (TCLP) formulated by USEPA [8].…”

Temperature Dependence of Nickel Stabilization in Inorganic Oxide Matrices

“…The artificially Ni-contaminated latosol was prepared as follows. Slurry containing 1.5 L of 198.13 g Ni(NO 3 ) 2 . 6 H 2 O solution and 1 kg latosol was end-to-end rotated in a bottle at a speed of 30 revolutions/min for 2 days.…”

“…A thermal process has been demonstrated to successfully encapsulate trace metals in soils under U.S. Environmental Protection Agency innovative technology evaluation emerging technology program. 2 However, no molecular-level information on Ni in soils after high-temperature melting or a sintering process is available to date. This information is critical from the aspects of both long-term stabilization and resource recycling.…”