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Environmental Technology Listing
Title of Listing:
DECAF
Category:
Treatment Technologies
Subcategory:
 *Waste, Soil, All Listings
Media:
Soil, Sludge, Sediment
Contaminants:
Radioactive Fluoride, Other Radioactive Elements
Web Site:
Email:
102604.1711@compuserve.com
Technology Description:

ARS, Inc. has developed a reagent-based process for treating radioactively contaminated fluoride bearing wastes to produce nonhazardous and nonradioactive waste forms. The process extracts radioactive elements for recycle or disposal as a volume reduced material, reclaims metal values for recycling and recovers fluoride as a high-value salt used in aluminum smelting.

          The process begins with the counter-current digestion of waste residues to break up the refractive fluoride matrix. The waste is treated with select reagents to maximize mobilization of the matrix constituents. Metals, radionuclides, and fluoride compounds are mobilized from the waste residues to an aqueous phase, from which radionuclides are extracted, metal impurities precipitated, and smelter grade aluminum fluoride synthesized. Cake washing is performed to displace both radionuclides and fluoride from residue voids. The resulting residue is sufficiently low in radioactivity to be released to a non-radioactive landfill and passes fully the TCLP criteria to achieve a nonhazardous classification. Mother liquor and washwater is now ready for the extraction of radionuclides.

          Both solvent extraction and selective ion-exchange have been used to efficiently decontaminate liquors generated from the digestion process. After the radionuclides are removed, the metal impurities are precipitated and recovered. Aluminum is then added to synthesize aluminum salt. The salt is filtered off from the liquor and calcined to remove waters of hydration.

          The DeCaF process can treat sludges, residues, and sediments contaminated with radioactive elements as well as hazardous constituents. Treated wastes include uranium contaminated calcium fluoride matrices, rare earth ore residues, and fluorspar contaminated with uranium. The DeCaF technology can be applied to a wide variety of resource recovery and waste minimization projects like treatment of soils, mining wastes, conversion reboiler bottoms, and so forth. The process can be extended to not only treating the radioactively contaminated hazardous wastes, but also decontaminating residues while recovering metal values.

          A key feature of this process is that reagent chemicals are recovered and recycled. This reduces the amount of chemicals that can be consumed, thereby saving enormous amounts in operating costs.
Performance Status/
Limitations:

Performance Status:

          The DeCaF process has been successfully demonstrated at bench-scale, pilot-scale, and full-scale. A full-scale plant is functioning at present to extract uranium from calcium fluoride sediments.

          The process was demonstrated at the pilot-scale to recover valuable metal from fluoride bearing residues.

          Numerous bench-scale studies have been conducted on fluoride bearing leach residues, bed matrix filter fines, heavy metal contaminated sediments and uranium contaminated magnesium fluoride and calcium fluoride residues.

          Limitations:

          The DeCaF process can be applied to a variety of wastes containing both radioactive and hazardous components. Some contaminants may be encompassed in a refractive matrix and difficult to extract. In such cases, a detailed bench-scale study will be needed to optimize the process parameters.
Topics
Mixed/Radioactive Waste, Technologies, Treatment/Remediation
Additional Topics/Tags/Keywords
Acid Extraction, Radioactive Fluoride

Organization:
ADVANCED RECOVERY SYSTEMS, INC.
Address:
1205 Banner Hill Road
Phone:
DescriptionNumber
City:
Erwin
1.
Primary (423) 743-2500
State/Province/Territory:
TN
2.
Zip/Postal Code:
37650
3.
Country:
United States
4.
Fax:(423) 743-2514
Branch Locations: