Stabilization of Rocky Flats Pu-contaminated ash within chemically bonded phosphate ceramics

Wagh, Arun S.; Strain, R.; Jeong, Sang Jin; Reed, D.T.; Krause, Theodore; Singh, Dileep

doi:10.1016/s0022-3115(98)00650-3

Cited by 113 publications

(66 citation statements)

References 13 publications

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“…In this case, for Pb-bearing samples, the pD e achieved was as high as 19.84, which implied a very low mobility. Taking into account the different units and leaching periods used, our diffusion coefficient was comparable with reported values for S/S processes of Pb in other matrices (Wagh et al, 1997;Moon and Dermatas, 2006).…”

Section: Leaching Studiessupporting

confidence: 87%

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Treatment of toxic metal aqueous solutions: Encapsulation in a phosphate-calcium aluminate matrix

Fernández

Navarro-Blasco

Durán

et al. 2014

Journal of Environmental Management

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Polyphosphate-modified calcium aluminate cement matrices were prepared by using aqueous solutions polluted with toxic metals as mixing water to obtain wastecontaining solid blocks with improved management and disposal. Synthetically contaminated waters containing either Pb or Cu or Zn were incorporated into phosphoaluminate cement mortars and the effects of the metal's presence on setting time and mechanical performance were assessed. Sorption and leaching tests were also executed and both retention and release patterns were investigated. For all three metals, high uptake capacities as well as percentages of retention larger than 99.9% were measured. Both Pb and Cu were seen to be largely compatible with this cementitious matrix, rendering the obtained blocks suitable for landfilling or for building purposes. However, Zn spoilt the compressive strength values because of its reaction with hydrogen phosphate anions, hindering the development of the binding matrix.

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Section: Leaching Studiessupporting

confidence: 87%

“…This fact can be readily understood in view of the major insolubility of the Zn hydrophosphates obtained (Wagh et al, 1999). Therefore, a physical encapsulation of these compounds could be reasonably assumed.…”

Section: Metal-binder Interactionmentioning

confidence: 89%

Treatment of toxic metal aqueous solutions: Encapsulation in a phosphate-calcium aluminate matrix

Fernández

Navarro-Blasco

Durán

et al. 2014

Journal of Environmental Management

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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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“…De acuerdo con la estequiometría 1:1 de la reacción de formación del correspondiente fosfato de magnesio y potasio [2], [2] y teniendo en cuenta la pureza de los reactivos utilizados en el presente trabajo de investigación, alrededor de un 68% de óxido de magnesio para el producto (LG) (Tabla I) y de un 99.8% de KH 2 PO 4 en el dihidrogenofosfato de potasio comercial empleado (K), sería necesaria una relación másica KH 2 PO 4 /MgO de 2,33 (≅ 70/30). Sin embargo, dada la escasa reactividad del óxido de magnesio (LG), así como por la realización de ensayos previos de formulación, se ha creído conveniente aumentar el porcentaje de (LG), de forma que prácticamente se ha invertido la relación estequiométrica expresada anteriormente.…”

Section: Caracterización Del Mortero Frescounclassified

“…En algunos casos, se hace necesario un pretratamiento inicial para reducir su reactividad, como sucede con el MgO de elevada pureza, al que se debe realizar una calcinación previa a 1300 ºC para obtener unas condiciones adecuadas de velocidad de disolución que permitan la correcta formación del CBPC (2).…”

Section: Introductionunclassified

Cementos químicos formulados con subproductos de óxido de magnesio

Formosa¹,

Aranda²,

Chimenos³

et al. 2008

Bol. Soc. Esp. Ceram. Vidr.

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Es posible obtener cementos de fosfato de magnesio y potasio (KMgPO 4 ·6H 2 O; K-estruvita), mediante la reacción en medio acuoso del óxido de magnesio y el dihidrogenofosfato de potasio, siendo ésta una reacción exotérmica muy rápida que permite el fraguado del material en pocos minutos. Estos cementos, formulados a partir de óxidos de magnesio de elevada pureza y coste elevado, se encuentran descritos en la bibliografía para su utilización en el encapsulamiento de residuos especiales y como morteros de cemento para la reparación de hormigón. Sin embargo cabe la posibilidad de poder formular este mismo tipo de cementos con óxidos de magnesio de bajo contenido, cuyo precio es del orden de 10 a 15 veces más barato que el óxido de magnesio de elevada pureza. En el presente estudio se evalúa la utilización de óxidos de magnesio de bajo contenido (≈70% MgO), obtenidos en el proceso de calcinación de la magnesita natural, para la formulación de cementos de K-estruvita. En este estudio se pretende determinar la formulación óptima de estos cementos a partir de la evaluación tanto de las propiedades mecánicas como de los tiempos de fraguado de las diferentes composiciones. Palabras clave: cementos de fosfato; K-estruvita; cementos químicos; fosfato de magnesio y potasio.Chemically bonded cements formulated with by-products of magnesium oxide.The casting of magnesium and potassium phosphate (KMgPO 4 ·6H 2 O; K-struvite) cements becomes possible after the aqueous reaction between magnesium oxide and potassium dihydrogen phosphate. This reaction is quite exothermic and allows the resulting paste setting in just few minutes. Those cements, when are cast with magnesium oxides of high purity, are used to retain and encapsulate special residues and as repairing concrete mortar, as it is described in the bibliography. However, it is also possible formulate those cements using low grade magnesium oxides, which cost are nearly 10 or 15 times cheaper than those of high grade. The aim of this work is to evaluate the possibility of using low grade magnesium oxides (≈70% MgO), obtained from the calcinations process of natural magnesites, for KMgPO 4 ·6H 2 O cement casting. The research and selection of the best formulation for obtaining that cement will be done also from the point of view of their mechanical properties as for their setting time.Key words: phosphate cement, K-struvite, chemical cement, magnesium and potassium phosphate. INTRODUCCIóNEl cemento Pórtland es el cemento más utilizado, dado que abarca un amplio rango de propiedades y posibilidades de uso, siendo a su vez un material económico. Sin embargo, en los últimos años se han desarrollado otros tipos de cementos más específicos que permiten ampliar el rango de trabajo y la aplicación de los mismos en otros campos de la tecnología. Entre estos tipos de cementos de nuevo desarrollo se incluyen los denominados cementos cerámicos enlazados químicamente.En general, estos cementos se obtienen a partir de la reacción química ácido-base entre un metal catiónico y una fuente ...

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Stabilization of Rocky Flats Pu-contaminated ash within chemically bonded phosphate ceramics

Cited by 113 publications

References 13 publications

Treatment of toxic metal aqueous solutions: Encapsulation in a phosphate-calcium aluminate matrix

Treatment of toxic metal aqueous solutions: Encapsulation in a phosphate-calcium aluminate matrix

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

Cementos químicos formulados con subproductos de óxido de magnesio

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