Characterization of Mg-clays from the Neogene of the Madrid Basin and their potential as backfilling and sealing material in high level radioactive waste disposal

Cuevas, Jaime; Pelayo, M.; Rivas, Pedro José; Leguey, Santiago

doi:10.1016/0169-1317(93)90004-k

Cited by 24 publications

(19 citation statements)

References 28 publications

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“…Sample EX M 1694 from the Madrid basin (Spain) is similar to the pink clay from the same provenance studied by Martin de Vidales [3] and Cuevas et al [4], but the interstratification consists of 30% turbostratic talc and 70% saponite type III rather than turbostratic talc and stevensite (due to tetrahedral and octahedral substitutions). In addition to the interstratification (75%), the sample contained 25% turbostratic talc.…”

Section: Discussionmentioning

confidence: 77%

“…Turbostratic talc/trioctahedral smectite interstratifications occur, for example, in the Province Parma (Italy) [1], in the Armagosa Desert (Nevada) [2], and in the Madrid basin (Spain) [3][4][5][6], which is the most extensive studied locality. The interstratifications are often very fine-grained and analysis and description of the interstratification is still difficult.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of a Fine-Grained Interstratification of Turbostratic Talc and Saponite

et al. 2017

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Abstract:Interstratifications of talc and trioctahedral smectites from different provenances are used as indicators for geological environments and for geotechnical and technical applications. However, comprehensive layer characterization of these interstratifications is rare. Sample EX M 1694, a clay with red-beige appearance from the Madrid basin was studied by X-ray diffraction analysis, X-ray fluorescence analysis, Fourier transformation infrared spectroscopy, simultaneous thermal analysis, gas adsorption measurements, cation exchange capacity, and environmental scanning electron microscopy. More than 95% of particles in EX M 1964 belong to the clay fraction <2 µm. It contains 75% interstratification of 30% turbostratic talc, and 70% saponite type III and 25% turbostratic talc. The turbostratic talc(0.3)/saponite interstratification is characterized by a low number of layers per stack (3), small lateral dimension of layers (60-80 nm) and, accordingly, a high specific surface area (283 m 2 /g) with nearly equal surface area of micro-and mesopores. Thus, the studied material can be used as mined for adsorption, in contrast to acid-treated clays that produce hazardous waste during production. Low particle size of the interstratification drastically reduced thermal stability and dehydroxylation was superimposed by recrystallization of high temperature phases already at 816 • C, which is low for trioctahedral 2:1 layer minerals.

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Section: Discussionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Characterization of a Fine-Grained Interstratification of Turbostratic Talc and Saponite

et al. 2017

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“…The composition of some of these Mg smectites can easily be explained by addition of Mg silicate (stevensite or kerolite) layers to the preexisting minerals of the dioctahedral phyllosilicate group (illite, beidellite). In contrast, some of the Vicálvaro and Madrid Basin saponitic clays are closer to the trioctahedral end-member (Galán et al, 1986;Cuevas et al, 1993). A problem arises as to whether Mg smectites of saponitic composition and sedimentary (lacustrine) origin can be considered as di-trioctahedral mixtures or true saponites.…”

Section: Introductionmentioning

confidence: 92%

“…Several authors have characterized different trioctahedral smectite-group minerals in this area, mainly saponite, stevensite or interstratified kerolite-stevensite (Galán et al, 1986;Martin de Vidales et al, 1988Ordoñ ez et al, 1991;Cuevas et al, 1993;De Santiago et al, 2000).…”

Section: Introductionmentioning

confidence: 96%

Chemistry of Mg Smectites in Lacustrine Sediments from the Vicalvaro Sepiolite Deposit, Madrid Neogene Basin (Spain)

Cuevas

Villa

Ramı́rez

et al. 2003

Clays and clay miner.

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The chemical and structural properties of Mg smectites in the Vicálvaro sepiolite deposit have been studied in detail. The characterization was performed on different size-fractions of selected smectitic samples (5À2 mm; 2À1 mm; 1À0.5 mm; <0.5 mm and <0.1 mm). The chemical compositions of individual particles (5À1 mm) and of bulk undifferentiated fine fractions (1À<0.1 mm) were determined by energy dispersive spectroscopy-scanning electron microscopy and interpreted with the aid of X-ray diffraction (XRD) and infrared spectroscopy (IR) methods. The XRD and IR data demonstrate that all of the Mg smectite materials studied are mainly composed of a complex mixture of stevensite, saponite and micatype minerals. Although the presence or absence of saponite cannot be confirmed absolutely, stevensite is a significant component of these Mg smectites. This is proven by the calculated layer charge reduction after the Hofmann-Klemen effect. The results are in close agreement with the suggested mechanism of topotactic overgrowth of stevensite on pre-existing phyllosilicate templates. This characterizes clay diagenesis in saline-lake systems.

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“…Los estudios de caracterización química y mineralógica llevados a cabo (Cuevas, 1992), demuestran unas cualidades a priori favorables para su uso, al presentar contenidos medios en esmectita en torno al 80 %, una capacidad de intercambio catiónico de 75 meq/100 g, y bajos contenidos en óxidos amorfos no cristalinos « 0,5 %), materia orgánica « 0,1 %) y carbonatos « 0,1 %), que pudieran afectar como fases cementantes o modificadoras químicas al comportamiento termo-mecá-nico de la esmectita. La fórmula estructural media de las esmectitas más libres de impurezas analizadas en fracción < 0,5 Itm (Cuevas et al, 1992b) corresponde a: X+0787K+0070 (Mg4326Alo663Fe3+032Fe2+0023 4 VI' , , , , , Ti +0,027) (AIo,663Si7,337)IV(Oho(OH)4 reflejando su composición saponítica.…”

Section: Introductionunclassified

Untitled

Rodríguez¹

1993

Estud. geol.

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RESUMENEl comportamiento hidrotermal de las arcillas saponíticas de origen sedimentario de la Cuenca de Madrid ha sido investigado en función de su uso potencial como barrera geoquímica en el almacenamiento de residuos radiactivos de alta actividad. Este artículo es una revisión de los aspectos estudiados hasta el momento: la adsorción y fijación irreversible de K+, la alteración en ausencia de potasio y los efectos del vapor de agua a elevada temperatura en las características texturales de la arcilla. Los experimentos se han realizado a temperaturas de hasta 175 0 C con agua líquida en exceso, excepto aquéllos con vapor de agua como medio de reacción predominante.Los análisis químicos y de DRX realizados sobre los productos de reacción indican que la saponita sufre alteraciones mínimas en las condiciones hidrotermales experimentadas tanto en ausencia como en presencia de potasio. No se ha detectado la evolución de procesos de ilitización o cloritización a expensas de la esmectita. Se ha encontrado que la sepiolita se disuelve en gran medida a 175 0 C, inhibiendo los procesos de recristalización o formación de ilita identificados cuando este mineral estuvo presente en cantidades apreciables en la arcilla de partida. Los minerales accesorios que acompañan a la saponita, una vez purificada, en forma de trazas (ilita y sepiolita), sufren una intensa degradación en ausencia de potasio. Por otro lado, las arcillas tratadas con vapor de agua a 200 0 C muestran visibles cambios en cuanto a su organización textural a causa de la formación de agregados en tamaño limo, estables frente a la dispersión, que provocan una importante pérdida de las propiedades expansivas de la arcilla saponítica. Este hecho había sido apuntado anteriormente en arcillas montmorilloníticas. ABSTRACTThe hydrothermal behavior of sedimentary saponitic clays from Madrid Basin has been investigated to assess their potential use as a buffer material in high level radioactive waste repositories. This paper deals with a rewiew of several aspects that has been studied: the adsorption and irreversible fixation of K+, the alteration in absence of potasium and the effects of heat and steam on textural properties of the smectitic clay. Experiments have covered temperatures up to 175 0 C with an excess of liquid water except on the last subject. Chemical and XRD analyses of final clay products and solutions indicates minor alteration of the saponite in the hydrothermal experiments either in the presence or absence of potasium. No illitization or chloritization processes seems to affect the smectite. Sepiolite was found to be largely dissolved at 175 0 C, a process that inhibited recrystallization or formation of illite observed when illite was present in significant amounts in starting materials. Accessory minerals (illite and sepiolite) accompayning as traces the saponitic material underwent and intense degradation at 175 0 C in absence of potasium. On the other hand, clay steamed at 200 0 C showed significant textural changes forming highly stable silt si...

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Characterization of Mg-clays from the Neogene of the Madrid Basin and their potential as backfilling and sealing material in high level radioactive waste disposal

Cited by 24 publications

References 28 publications

Characterization of a Fine-Grained Interstratification of Turbostratic Talc and Saponite

Characterization of a Fine-Grained Interstratification of Turbostratic Talc and Saponite

Chemistry of Mg Smectites in Lacustrine Sediments from the Vicalvaro Sepiolite Deposit, Madrid Neogene Basin (Spain)

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