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DOE TECHNOLOGY OVERVIEW
Process To stabilize low level and mixed waste streams, various types of Portland cement are combined with ground granulated blast furnace slag cement, and in some cases, silica fume or fly ash. Multiple admixtures are used to achieve specific properties. A gelling agent is added to produce a grout with zero bleed water. A high range water reducer or super plasticizer is added to reduce water-to-cement ratio and increase the flow and self leveling properties of the grout. A metallic silicate is added as an encapsulating agent. A waterproofing agent is used to add cohesive property to the grout mix. The blending of these various ingredients creates a highly flexible stabilization system using grout.
If the AII grout is to be used as a filler, the strength of the grout can be varied by adjusting the amount of sand added to the mix. When the AII grout is used as an encapsulating grout, the waste materials can be mixed directly into the grout, with the overall strength of the grout being dependent on the waste loading.
Experimentation and Results AII has collaborated with the Chemical Technologies Division of Argonne National Lab (ANL) for the past four years. The stabilization experiments involving both solids and sludges (low level and mixed wastes) containing Tc, U, Cs and many hazardous heavy metals were conducted at ANL using AII’s formulae. AII’s grout was loaded with up to 50% waste by weight. Leach index tests were conducted using ANS 16.1 protocol. The ANS 16.1 leach index numbers for various radionuclides and hazardous heavy metals are as follows: Tc-15, U-22, Cs-15, Cd-18.5, Hg-16, Ba-15, and As-18.4. These leach index values are greater than those reported in the literature. In another series of experiments three different Hg contaminated soils were stabilized. TCLP testing was conducted on the stabilized materials. One soil with 2,100 ppm Hg was stabilized to 0.0007 ppm Hg. The waste loading for this soil was 70% by weight. In another soil with 21,400 ppm Hg, and loaded with 50% waste by weight, the stabilized mass passed TCLP testing with 0.193 ppm Hg.
Technical Advantages AII’s grout has attractive properties for low level waste immobilization which include:
AII’s grout was specifically designed for use in a continuous - volumetric rotating auger mixer. Through years of actual hands-on experience with volumetric mixing equipment, AII developed a feasible and also very practical system for the stabilization of low level and mixed waste streams.
Application To Department of Energy (DOE) Sites As a grout and mixing system combination this material is flexible enough to replace numerous current technologies that are narrowly focused. Volumetric mixing allows for easy and accurate changes to the grout design. This is often beneficial to meet changing project demands. AII’s grout system would be an excellent candidate for many Department of Energy site projects. For example, at the Savannah River Site (SRS), AII’s grout could be used instead of three separate grouts for tank closure (Caldwell, T.B., et al., "Closing High-Level-Waste Tanks at the Savannah River Site," Radwaste Magazine, March, 1998.) AII’s grout would make a good candidate for Cs encapsulation for the in-tank process (ITP) at the SRS. Test data has already shown that AII’s grout could be a candidate for Tc immobilization at the SRS and Hanford and other DOE sites. For further information please contact Ronald R. Weszely, President.
U. S. Patents held by Applied Innovations, Inc. 5709466 Mixer for cementitious materials
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