Experimental synthesis of chlorite from smectite at 300ºC in the presence of metallic Fe D. Guillaume, A. Neaman, M. Cathelineau, Régine Mosser-Ruck, C. Peiffert, Mustapha Abdelmoula, J. Dubessy, F. Villieras, A. Baronnet, N. Michau To cite this version: D. Guillaume, A. Neaman, M. Cathelineau, Régine Mosser-Ruck, C. Peiffert, et al.. Experimental synthesis of chlorite from smectite at 300ºC in the presence of metallic Fe. Clay Minerals, Mineralogical Society, 2003, 38 (3), pp.281-302. 10.1180/0009855033830096. hal-01876608 HAL Id: hal-01876608 https://hal.univ-lorraine.fr/hal-01876608 Submitted on 18 Sep 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. ClayMinerals (2003)38, 281–302 Experimentalsynthesisofchloritefrom smectiteat300ºCinthepresenceof metallic Fe D.GUILLAUME 1,* , { , A . N E A MA N 2,M.CATHELINEAU 1, R.MOSSER-RUCK 1,C.PEIFFERT 1,M.ABDELMOULA 3, J. D U BE SSY 1, 2 4 5 F. V I L LI E´ RA S ,A.BARONNET AND N . M IC H A U 1 Ge´ologieet Gestion des Ressources Mine ´raleset Energe ´tiques(G2R ),UMR 7566 CNRS-CREGU-INPL-UHP, Universite´ HenriPoincare ´,BP239,54506 Vandœuvre-le `s-Nancy, 2 LaboratoireEnvironnement et Mine ´ralurgie (LEM),UMR 7569 CNRS-INPL, EcoleNationale Supe ´rieurede Ge ´ologie,BP 40,54501 Vandœuvre-le `s-Nancy, 3 Laboratoirede Chimie Physique et Microbiologie pour l’ Environnement (LCPME), UMR 7564 CNRS-UHP, Universite´HenriPoincare ´,405 ruede Vandœ uvre, 54600 Villers-le`s-Nancy, 4 Centrede Recherchesur les Me ´canismes deCroissance Cristalline CRMC2-CNRS, Campus Luminy,case 913, 13288 Marseille,and 5 Agencenationale pour la gestiondes de ´chetsradioactifs (ANDRA), DirectionScientifique/ ServiceMate ´riaux,Parc de la Croix Blanche, 1/ 7rue JeanMonnet, 92298 Chaˆtenay-Malabry,France (Received 28 January 2002; revised 7November 2002 ) ABSTRACT:The alteration and transformation behaviour of montmorillonite (bentonite from Wyoming, MX-80) in low-salinity solutions (NaCl, CaCl 2)in the presence of metallic Fe (powder and 86461mmplate) and magnetite powder was studied in batch experiments at 300ºC to simulate the mineralogical and chemical reactions of clays in contact with steel in anuclear waste repository. The evolutions of pH and solution concentrations were measured over aperiod of 9months. The mineralogical and chemical evolution of the clays was studied by XRD,SEM, Transmission Mo¨ssbauer Spectroscopy and TEM(EDS, HR imaging and EELS).Dissolution of the di-octahedral smectite of the starting bentonite was observed, in favour of newly formed clays (chlorite and saponite), quartz, feldspars and zeolite. The formation of Fe-chlorite was triggered by contact with the metallic Feplate and Fe-Mg-chlorite at distance from the Fe plate (>2 mm). KEYWORDS:bentonite,smectite, Fe, magnetite,chlorite, saponite, experimental synthesis, EELS-TEM, EDS-TEM, HRTEM imaging,Mo ¨ssbauerspectroscopy. Bentonitesare frequently recommended as backfill compactedto high density and their high sorption materialsfor the construction of high-level nuclear capacity.If the natural occurrence of old bentonites wastereposit ories.Differe ntconcept sforesee isan indication of their long-term stability, the very emplacingsteel containers in tunnels backfilled specificconditions of high-level nuclear wastes withcompactedbentonite(Madsen,1998). repositorysites has to be taken into account, Bentonitesare choosen because of their swelling particularlythe tempera tureincreas eandthe capacity,their low hydraulic conductivity when eventualpresence of available Fe. To this end, interactionsbetween the bentonite and the container corrosionproducts are of particular interest. The *E-mail: [email protected] keyproblem is the permanence or not of swelling { present address: Westfa¨lische Wilhelms-Universita ¨t Mu¨nster, Institut fu¨rMineralogie, Corrensstr. 24, 48149 minerals.Previous studies of the evolution of clay Mu¨nster, Germany mineralsin different natural contexts may provide DOI: 10.1180/0009855033830096 partof the answer. # 2003The Mineralogical Society 282 D.Guillaume et al. Duringdiagenesis and low-temperature meta- numberof studies, the formation of minor amounts morphismof intermediate to mafic volcanic rocks offramework silicates after clay minerals was andvolcanogenic sediments, chlorite may crystal- reported,but not studied in detail. The stability of lizefrom mineral precursors through complex smectitein the presence of Fe underlow f is still O2 processesincluding the crystallization of mixed- poorlystudied. Mu ¨ller-Vonmoos et al. (1991) and layerminerals (Bettison & Schiffman,1988). Madsen(1998) studied the hydrothermal stability of Previousworks suggest that precursors may be a bentonitein the presence of Fe andmagnetite smectiteor other minerals such as berthierine powdersat 80º C overa periodof 27 to 29 weeks, (Aagaard et al.,2000)which transform into chlorite butinasystemfreeof li quidwa ter.No inresponset oanincreaseo ftemperature mineralogicalchange was detected at this tempera- (Hoffmann&Hower,19 79;Horton,1 985; ture.However,thermodynamicmodelling Bettison&Schiffman,1 988;Schiffman& (Cathelineau et al.,2001) predic tsa strong Fridleifsson,19 91;Hu mpreys et al., 1994; mineralogicalevolution of the bentonite, especially Robinson& Santanade Zamora, 1999). The theformation of a chlorite-saponite-zeoliteassem- transitionmay occur in a steppedprogression of blage,when the smectite-Fe system interacts with a smectiteto chlorite via corrensite or as a gradual solutionat a temperature>150º C. changeinvolving randomly or regularly interlayered Inconclusion, the formation of chlorite is a structures(chlorite-smectit e:C-S), as dictated by possibility,establishe dbothfrom natural case theenvironment of formation (Bettison-Varga & studiesand thermodynamic simulations. However, Mackinnon,1997). The role of fluid composition, theavailability of native Fe incontact with clay porosityand water/ rockratio (W/ R)indetermining mineralsin a high-levelnuclear waste repository thestability of those minerals has been recognized. andits consequences for the evolution of clay Therole of low W/ Rratioin the stabilization of mineralscannot be establis hedfrom previous C-S isemphasized (Alt et al.,1986;Schiffman & studies.Therefore,experimentshavebeen Staudigel,1995; Bettison-Var ga& Mackinnon, performedto investigate the hydrothermal stability 1997).Murakami et al.(1999)provided HRTEM ofa bentoniteat 300º C inthe presence of metallic evidencefor the mechanism of the saponite-to- Fe andmagnetite, and particularly the transforma- chloriteconversion in thermally metamorphosed tionof montmorillonite into Fe-rich clay phases, volcanoclasticrocks and Robinson et al. (2002) suchas sapo niteand /orchlo rite.Analy tical gavea reviewof reactio npathwaysfor the investigationsconcerned both solid and liquid smectite-to-chloritetransformation in geothermal phases.Clay minerals were characterized by their systems.However the complex structura land structural(X-ray Diffraction – XRD, Scanning compositionalchanges that accompany the trans- ElectronMicroscopy – SEM andHigh-Resolution formationare not entirely understood (Meunier et TransmissionElectron Microsco py– HRTEM al.,1991;Inoue & Utada,1991), and the conditions imaging)andchemicalproperties(Cation favourablefor the formation of chlorite have not ExchangeCapacity–CEC,Transmission beenfully determin edin most natural cases. Mo¨ssbauerSpectroscopy – TMS, ElectronEnergy- Elementarythermodynamic considerations indicate LossSpectroscopy – EELS andEnergy Dispersive thatFe-chlorite can only form when the Fe 2+/H+ Spectroscopy(EDS)-TEM). Theexperimental solu- ratiois high enough (Bowers et al., 1984). tionscoexistin gwiththe solid products were Thesmectite-to-chlo ritetransformation has not characterizedby inductively coupled-atomic emis- beenreproduced experimentally. Small et al. (1992) sionspectro scopy(ICP-AES) andinducti vely indicatedthat no chlorit ecouldbe obtaine d coupledplasma-mass spectroscopy (ICP-MS). experimentallyunder laboratory conditions below 400ºC, confirmingprevious statements from Gillery MATERIALSANDMETHODS (1959)and Velde (1973) .Thehyd rothermal stabilityof smectite has been studied extensively, Starting material especiallythe collapse of expandable smectite to non-expandablelayer silicates, in particular illite, TheMX80bentonite(Na/Ca-bentonite, generallyin mineral-solution systems devoid of Wyoming),referred to as ‘ startingbentonite’ , was addedFe (e.g.Eberl et al.,1993; Cuadros & usedfor the experiments. Its CEC is79 mEq/ 100g Linares,1996; Mosser-Ruck et al.,2001).In a (Table1) and its co mpositionis as fo llows Experimental synthesis of chlorite 283 (Guillaume et al.,2001a): montmorillonite (79%), preparationwas equilibrated at room temperature quartz(3%), K-feldspar (2%), plagioclase (9%), for6 days.The solution pH was then measured carbonates(2%), mica (3%) and other minerals usinga Mettler 1 combinationpH electrode at (mostlypyrite, phosphates and hematite, 2%). The 25ºC, andthe Na +/Ca2+ ratioof the reacting structuralformula of the montmorillonite (<2 mm solutionwas