Chemically bonded phosphate ceramics for low‐level mixed‐waste stabilization

Singh, Dileep; Wagh, Arun S.; Cunnane, J.C.; Mayberry, J.L.

doi:10.1080/10934529709376559

Cited by 30 publications

(27 citation statements)

References 3 publications

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“…Their properties also include: low water demand, low drying shrinkage, and high early compressive strength 1 , which has favoured application of MKPCs to radioactive waste encapsulation 2 . MKPCs have been extensively researched at the Argonne National Laboratory (ANL), USA, to encapsulate wastes that are not compatible with standard cementation (blended Portland cement) such as nitrated wastes and Pu contaminated materials [3][4][5][6][7][8][9] . In the UK, the near-neutral pH and low water demand properties of MKPCs are advantageous in the immobilisation of radioactive reactive metals (Al, Mg and U), which could otherwise corrode in the highly alkaline and/or high free water environment of Portland cement 2, 10-12 .…”

Section: Introductionmentioning

confidence: 99%

Evolution of phase assemblage of blended magnesium potassium phosphate cement binders at 200° and 1000°C

Gardner

Lejeune

Corkhill

et al. 2015

Advances in Applied Ceramics

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The fire performance of magnesium potassium phosphate cement (MKPC) binders blended with fly ash (FA) and ground granulated blast furnace slag (GBFS) was investigated up to 1000 °C using XRD, TGA, and SEM techniques. The FA/MKPC and GBFS/MKPC binders dehydrate above 200 °C to form amorphous KMgPO 4 , concurrent with volumetric and mass changes. Above 1000 °C, additional crystalline phases were formed and microstructural changes occurred, although no cracking or spalling of the samples was observed. These results indicate that FA/MKPC and GBFS/MKPC binders are expected to have satisfactory fire performance under the fire scenario conditions relevant to the operation of a UK or other geological disposal facility.

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Section: Introductionmentioning

confidence: 99%

Evolution of phase assemblage of blended magnesium potassium phosphate cement binders at 200° and 1000°C

Gardner

Lejeune

Corkhill

et al. 2015

Advances in Applied Ceramics

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“…4 This technology is based on synthetically produced, newberyiterich magnesium phosphate ceramic and is intended for stabilization of the DOE's low-level mixed waste streams. 5 Since newberyite 6 has high strength and low solubility (10 -6 ), the magnesium phosphate matrix can be a very stable ceramic in an aqueous environment, hence making it a good candidate for stabilizing waste streams.…”

Section: Introductionmentioning

confidence: 99%

Stabilization and Solidification of Metal-Laden Wastes by Compaction and Magnesium Phosphate-Based Binder

Rao

Pagilla

Wagh

2000

Journal of the Air & Waste Management Association

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Bench-scale and full-scale investigations of waste stabilization and volume reduction were conducted using spiked soil and ash wastes containing heavy metals such as Cd, Cr, Pb, Ni, and Hg. The waste streams were stabilized and solidified using chemically bonded phosphate ceramic (CBPC) binder, and then compacted by either uniaxial or harmonic press for volume reduction. The physical properties of the final waste forms were determined by measuring volume reduction, density, porosity, and compressive strength. The leachability of heavy metals in the final waste forms was determined by a toxicity characteristic leaching procedure (TCLP) test and a 90-day immersion test (ANS 16.1). The structural composition and nature of waste forms were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively.CBPC binder and compaction can achieve 80-wt % waste loading and 39-47% reduction in waste volume. Compressive strength of final waste forms ranged from 1500 to 2000 psi. TCLP testing of waste forms showed that all heavy metals except Hg passed the TCLP limits using the phosphate-based binder. When Na 2 S was added to the binder, the waste forms also passed TCLP limits for Hg. Long-term leachability resistance of the final waste forms was achieved for all metals in both soil and ash IMPLICATIONS Hundreds of millions of dollars are spent by businesses and the government for the treatment and disposal of hazardous waste. This project researched a stabilization and solidification method involving CBPCs. This method reduces heavy metal mobility in soil and ash wastes by producing relatively inert waste forms with good structural properties. In addition, it reduces the final volume of the waste, leading to reduction in transportation and landfill disposal costs.wastes, and the leachability index was ~14. XRD patterns of waste forms indicated vermiculite in the ash waste was chemically incorporated into the CBPC matrix. SEM showed that waste forms are layered when compacted by uniaxial press and are homogeneous when compacted by harmonic press. INTRODUCTIONThe U.S. Department of Energy (DOE) has generated large volumes of low-level radioactive, hazardous, and mixed wastes as a result of its energy-and defense-related research over the last 60 years.1 Having acknowledged this problem, the DOE has funded several projects in its research laboratories in an effort to find an easy, cost-effective, and safe means of disposing this waste. Much of the DOE waste streams containing heavy metals and radionuclides require solidification/stabilization (S/S) before final disposal to reduce the mobility of contaminants into the environment. The most common practice at DOE and commercial facilities is to solidify waste using Portland cement.Although cement stabilization processes are inexpensive, readily available, and easy to process, there are limitations. In most commercial cement stabilization processes, contaminant metals are precipitated as insoluble hydroxides, which have minimum solubility between...

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“…A combination of ionic and covalent bonds between the mineral phases and ceramic matrix provides a sound structural, essentially nonporous, pH-neutral mineral matrix that can incorporate high concentrations of metals and salts. The specific aspects of the fabrication process change with the various applications of the material for this patented technology (Singh et al 1997, Wagh 2004). These applications include, but are not limited to, 1) treating mixed and low-level wastes (LLWs) (magnesium potassium phosphate and iron phosphate), 2) macro-encapsulating and containerizing uranium (doped ceramicrete), 3) repairing roads and highways, 4) drilling casing and capping in the oil industry (aluminum phosphate [Berlinite]), and 5) medical/dental industry application (calcium and zinc phosphate).…”

Section: Chemically Bonded Phosphate Ceramicsmentioning

confidence: 99%

Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams

Pierce¹,

Mattigod²,

Westsik³

et al. 2010

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Executive SummaryPacific Northwest National Laboratory has initiated a waste-form testing program to support the longterm durability evaluation of a waste form for secondary wastes generated from the treatment and immobilization of Hanford radioactive tank wastes. The purpose of the work discussed in this report is to identify candidate stabilization technologies and getters that have the potential to successfully treat the secondary waste stream liquid effluent, mainly from off-gas scrubbers and spent solids, produced by the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Down-selection to the most promising stabilization processes/waste forms is needed to support the design of a solidification treatment unit (STU) to be added to the Effluent Treatment Facility (ETF). To support key decision processes, an initial screening of the secondary liquid waste forms must be completed by February 2010. Later, more comprehensive and longer term performance testing will be conducted, following the guidance provided by the secondary waste-form selection, development, and performance evaluation roadmap. The resulting waste form will be compliant to regulations and performance criteria and will lead to cost-effective disposal of the secondary wastes.This report starts with a brief review of some of the most commonly used solidification formulations that would be candidates for secondary liquid waste streams. In this review, the available data on performance are discussed, and some preliminary recommendations are provided for materials that should undergo additional screening testing. We also 1) discuss options for disposal of WTP secondary solid waste streams, 2) provide a brief overview of standard regulatory test methods used for measuring contaminant leachability and waste-form physical strength (with emphasis on the U.S. Environmental Protection Agency's [EPA's] new methods as a screening tool for comparing waste solidification materials of interest), and 3) provide an overview of factors that must be considered in long-term performance testing, including state-of-the-art characterization tools that can provide the data needed to technically defend predictive modeling simulations of long-term material behavior. The long-term wasteform testing and solid and leachate characterization must be robust enough to effectively predict material performance in the Integrated Disposal Facility over the 10,000-year period of performance for the engineered system. The solidification technologies for liquid waste streams include cement/grout, containerized Cast Stone, phosphate-bonded ceramics, alkali-aluminosilicate geopolymers, hydroceramics, L-TEM, and fluidized-bed steam reforming (FBSR). In addition to these, other mature technologies and two compounds, namely goethite and sodalite (that are still being developed), that show considerable promise as waste forms or getters are also discussed. It is our recommendation, based upon the available literature, that Cast Stone, chemically bonded phosphate ceramics (Ceramicrete...

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Chemically bonded phosphate ceramics for low‐level mixed‐waste stabilization

Cited by 30 publications

References 3 publications

Evolution of phase assemblage of blended magnesium potassium phosphate cement binders at 200° and 1000°C

Evolution of phase assemblage of blended magnesium potassium phosphate cement binders at 200° and 1000°C

Stabilization and Solidification of Metal-Laden Wastes by Compaction and Magnesium Phosphate-Based Binder

Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams

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