Hostname: page-component-cd9895bd7-lnqnp Total loading time: 0 Render date: 2024-12-28T05:12:34.214Z Has data issue: false hasContentIssue false
  • English
  • Français

Microstructure of Bentonite in Iron Ore Green Pellets

Published online by Cambridge University Press:  07 January 2014

Iftekhar U. Bhuiyan ,
Johanne Mouzon ,
Birgit Schröppel ,
Andres Kaech ,
Illia Dobryden ,
Seija P.E. Forsmo  and
Jonas Hedlund
Iftekhar U. Bhuiyan
Affiliation:
Chemical Technology, Luleå University of Technology, SE-971 87 Luleå, Sweden
Johanne Mouzon*
Affiliation:
Chemical Technology, Luleå University of Technology, SE-971 87 Luleå, Sweden
Birgit Schröppel
Affiliation:
Natural and Medical Sciences Institute (NMI), University of Tübingen, 72 770 Reutlingen, Germany
Andres Kaech
Affiliation:
Center for Microscopy and Image Analysis, University of Zurich, CH-8006 Zurich, Switzerland
Illia Dobryden
Affiliation:
Division of Physics, Luleå University of Technology, SE-971 87 Luleå, Sweden
Seija P.E. Forsmo
Affiliation:
LKAB, R&D, SE-983 81 Malmberget, Sweden
Jonas Hedlund
Affiliation:
Chemical Technology, Luleå University of Technology, SE-971 87 Luleå, Sweden
*
*Corresponding author. E-mail: johanne.mouzon@ltu.se
Get access

Abstract

Sodium-activated calcium bentonite is used as a binder in iron ore pellets and is known to increase strength of both wet and dry iron ore green pellets. In this article, the microstructure of bentonite in magnetite pellets is revealed for the first time using scanning electron microscopy. The microstructure of bentonite in wet and dry iron ore pellets, as well as in distilled water, was imaged by various imaging techniques (e.g., imaging at low voltage with monochromatic and decelerated beam or low loss backscattered electrons) and cryogenic methods (i.e., high pressure freezing and plunge freezing in liquid ethane). In wet iron ore green pellets, clay tactoids (stacks of parallel primary clay platelets) were very well dispersed and formed a voluminous network occupying the space available between mineral particles. When the pellet was dried, bentonite was drawn to the contact points between the particles and formed solid bridges, which impart strength to the solid compact.

Keywords

microstructurehigh pressure freezingplunge freezingfreeze fracturecryo-SEMbentonitemagnetiteiron oregreen pellets
Type
Materials Applications
Information
Microscopy and Microanalysis , Volume 20 , Issue 1 , February 2014 , pp. 33 - 41
Copyright
Copyright © Microscopy Society of America 2014 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Broughton, G. & Squires, L. (1936). The gelation of bentonite suspensions. J Phys Chem 40(8), 1041–1053.CrossRefGoogle Scholar
Callaghan, I.C. & Ottewill, R.H. (1974). Interparticle forces in montmorillonite gels. Faraday Discuss Chem Soc 57, 110–118.CrossRefGoogle Scholar
Chenu, C. & Tessier, D. (1995). Low temperature scanning electron microscopy of clay and organic constituents and their relevance to soil microstructures. Scan Microsc 9(4), 989–1010.Google Scholar
Deville, S. (2008). Freeze-casting of porous ceramics: A review of current achievements and issues. Adv Eng Mater 10(3), 155–169.CrossRefGoogle Scholar
Forsmo, S.P.E. (2007). Influence of green pellet properties on pelletizing of magnetite iron ore. PhD Doctoral Thesis, Luleå University of Technology, Luleå. Available at http://epubl.ltu.se/1402-1544/2007/14/.Google Scholar
Forsmo, S.P.E., Apelqvist, A.J., Bjorkman, B.M.T. & Samskog, P.O. (2006). Binding mechanisms in wet iron ore green pellets with a bentonite binder. Powd Tech 169(3), 147–158.Google Scholar
Freundlich, H. (1928). Ueber thixotropie. Colloid Polym Sci 46(4), 289–299.Google Scholar
Frosien, J., Plies, E. & Anger, K. (1989). Compound magnetic and electrostatic lenses for low-voltage applications. J Vac Sci Tech B 7(6), 1874–1877.CrossRefGoogle Scholar
Galway, M.E., Heckman, J.W., Hyde, G.J. & Fowke, L.C. (1995). Advances in high-pressure and plunge-freeze fixation. In Methods in Plant Cell Biology, Galbraith, D.W., Bohnert, H.J. & Bourque, D.P. (Eds.), pp. 3–19. New York: Academic Press.Google Scholar
Gault, B., Marquis, E.A., Saxey, D.W., Hughes, G.M., Mangelinck, D., Toberer, E.S. & Snyder, G.J. (2010). High-resolution nanostructural investigation of Zn4Sb3 alloys. Scripta Materialia 63(7), 784–787.CrossRefGoogle Scholar
Goldschmidt, V.M. (1926). Undersøkelser over lersedimenter. Nordisk jordbrugsforskning 4–7, 434–445.Google Scholar
Goodeve, C.F. (1939). A general theory of thixotropy and viscosity. Trans Faraday Soc 35, 342–358.Google Scholar
Gu, B.H. & Doner, H.E. (1993). The microstructure of dilute clay and humic-acid suspensions revealed by freeze-fracture electron-microscopy—A reply. Clays Clay Miner 41(1), 114–116.CrossRefGoogle Scholar
Guyonnet, D., Gaucher, E., Gaboriau, H., Pons, C.H., Clinard, C., Norotte, W. & Didier, G. (2005). Geosynthetic clay liner interaction with leachate: Correlation between permeability, microstructure, and surface chemistry. J Geotech Geoenviron Eng 131(6), 740–749.CrossRefGoogle Scholar
Hauser, E.A. & Reed, C.E. (1937). Studies in thixotropy II. The thixotropic behavior structure of bentonite. J Phys Chem 41(7), 911–934.CrossRefGoogle Scholar
Henstra, A., Chmelik, J., Dingle, T., Mangnus, A. & van Veen, G. (2009). Versatile monochromator module for XHR SEM. Microsc Microanal 15(S2), 168.Google Scholar
Hofmann, U. & Hausdorf, A. (1945). Über das Sedimentvolumen und die Quellung von Bentonit. Colloid Polym Sci 110(1), 1–17.Google Scholar
Hohenberg, H., Mannweiler, K. & Muller, M. (1994). High-pressure freezing of cell-suspensions in cellulose capillary tubes. J Microsc 175, 34–43.Google Scholar
Holzer, L., Munch, B., Rizzi, M., Wepf, R., Marschall, P. & Graule, T. (2010). 3D-microstructure analysis of hydrated bentonite with cryo-stabilized pore water. Appl Clay Sci 47(3-4), 330–342.CrossRefGoogle Scholar
Jaksch, H. & Martin, J.P. (1995). High-resolution, low-voltage SEM for true surface imaging and analysis. Fresenius J Anal Chem 353(3-4), 378–382.Google ScholarPubMed
Kawatra, S.K. & Ripke, S.J. (2001). Developing and understanding the bentonite fiber bonding mechanism. Miner Eng 14(6), 647–659.Google Scholar
Kawatra, S.K. & Ripke, S.J. (2002). Effects of bentonite fiber formation in iron ore pelletization. Int J Miner Process 65(3-4), 141–149.Google Scholar
Keren, R., Shainberg, I. & Klein, E. (1988). Settling and flocculation value of sodium-montmorillonite particles in aqueous media. Soil Sci Soc Am J 52(1), 76–80.Google Scholar
Kim, K.W. & Jaksch, H. (2009). Compositional contrast of uncoated fungal spores and stained section-face by low-loss backscattered electron imaging. Micron 40(7), 724–729.Google Scholar
Lagaly, G. & Ziesmer, S. (2003). Colloid chemistry of clay minerals: The coagulation of montmorillonite dispersions. Adv Colloid Interface Sci 100, 105–128.Google Scholar
Lambe, T.W. (1953). The structure of inorganic soil. Paper presented at the Proc ASCE 79(1), 1–49.Google Scholar
Luckham, P.F. & Rossi, S. (1999). The colloidal and rheological properties of bentonite suspensions. Adv Colloid Interface Sci 82(1-3), 43–92.Google Scholar
McFarlane, A., Bremmell, K. & Addai-Mensah, J. (2006). Improved dewatering behavior of clay minerals dispersions via interfacial chemistry and particle interactions optimization. J Colloid Interface Sci 293(1), 116–127.Google Scholar
M'Ewen, M.B. & Pratt, M.I. (1957). The gelation of montmorillonite. Part 1—The formation of a structural framework in sols of Wyoming bentonite. Trans Faraday Soc 53, 535–547.CrossRefGoogle Scholar
Michael, J.R. (2010). Use of sample bias voltage for low-energy high-resolution imaging in the SEM. Microsc Microanal 16(S2), 614–615.Google Scholar
Michael, J.R., Joy, D.C. & Griffin, B.J. (2009). Challenges in achieving high resolution at low voltages in the SEM. Microsc Microanal 15, 660–661.CrossRefGoogle Scholar
Moor, H. (1971). Recent progress in the freeze-etching technique. Phil Trans R Soc Lond B 261(837), 121–131.Google Scholar
Moor, H. (1987). Theory and practice of high pressure freezing. In Cryotechniques in Biological Electron Microscopy, Steinbrech, R.A. & Zierold, K. (Eds.), pp. 175–191. Berlin: Springer-Verlag.CrossRefGoogle Scholar
Morris, G.E. & Zbik, M.S. (2009). Smectite suspension structural behaviour. Int J Miner Process 93(1), 20–25.CrossRefGoogle Scholar
Mpofu, P., Addai-Mensah, J. & Ralston, J. (2004). Flocculation and dewatering behaviour of smectite dispersions: Effect of polymer structure type. Miner Eng 17(3), 411–423.Google Scholar
Müllerová, I. & Frank, L. (1993). Very low energy microscopy in commercial SEMs. Scanning 15(4), 193.Google Scholar
Murray, H.H. (1991). Overview—Clay mineral applications. Appl Clay Sci 5(5-6), 379.Google Scholar
Norrish, K. (1954). The swelling of montmorillonite. Discuss Faraday Soc 18, 120.CrossRefGoogle Scholar
Norrish, K. & Rausell-Colom, J.A. (1963). Low-angle X-ray diffraction studies of the swelling of montmorillonite and vermiculite. Clays Clay Miner 10(1), 123.Google Scholar
Pusch, R. & Yong, R. (2005). Microstructure of Smectite Clays and Engineering Performance. London, New York: Taylor & Francis.Google Scholar
Qiu, G.Z., Jiang, T., Fan, X.H., Zhu, D.Q. & Huang, Z.C. (2004). Effects of binders on balling behaviors of iron ore concentrates. Scand J Metall 33(1), 39–46.Google Scholar
Rand, B., Pekenć, E., Goodwin, J.W. & Smith, R.W. (1980). Investigation into the existence of edge—Face coagulated structures in Na-montmorillonite suspensions. J Chem Soc Faraday Trans 1 76, 225–235.Google Scholar
Rosenqvist, I.T. (1959). Physico-chemical properties of soils: Soil-water system. J Soil Mech Fdns Div, Am Soc Civ Engrs 85, 31–53.Google Scholar
Ryan, K.P., Bald, W.B., Neumann, K., Simonsberger, P., Purse, D.H. & Nicholson, D.N. (1990). Cooling rate and ice-crystal measurement in biological specimens plunged into liquid ethane, propane, and freon-22. J Microsc 158, 365–378.Google Scholar
Segad, M., Hanski, S., Olsson, U., Ruokolainen, J., Akesson, T. & Jonsson, B. (2012). Microstructural and swelling properties of Ca and Na montmorillonite: (In Situ) Observations with Cryo-TEM and SAXS. J Phys Chem C 116(13), 7596–7601.CrossRefGoogle Scholar
Steigerwald, M.D.G. (2004). New detection system for GEMINI. Microsc Microanal 10(S02), 1372. Google Scholar
Steinbrecht, R.A. & Zierold, K. (1987). Cryotechniques in Biological Electron Microscopy. Berlin, Heidelberg, New York: Springer-Verlag.Google Scholar
Studer, D., Michel, M. & Muller, M. (1989). High-pressure freezing comes of age. Scan Microsc Suppl 3, 253–269.Google ScholarPubMed
Studer, D., Michel, M., Wohlwend, M., Hunziker, E.B. & Buschmann, M.D. (1995). Vitrification of articular-cartilage by high-pressure freezing. J Microsc 179, 321–332.Google Scholar
Terzaghi, K. (1925). Erdbaummechanik auf Bodenphysikalischer Grundlage. Franz Deuticke Press: Leipzig 399, ill. Google Scholar
Tessier, D., Lajudie, A. & Petit, J.C. (1992). Relation between the macroscopic behavior of clays and their microstructural properties. Appl Geochem 7, 151–161.Google Scholar
Tessier, D. & Pedro, G. (1982). Electron microscopy study of Na smectite fabric—Role of layer charge, salt concentration and suction parameters. Int Clay Conf 1981, Proc. 7th Conf. Bologna/Pavia, pp. 165–176.Google Scholar
Vali, H. & Bachmann, L. (1988). Ultrastructure and flow behavior of colloidal smectite dispersions. J Colloid Interface Sci 126(1), 278–291.Google Scholar
Van Olphen, H. (1956). Forces between suspended bentonite particles. Clays Clay Miner 4, 204–224.Google Scholar
Van Olphen, H. (1964). An introduction to clay colloid chemistry. Soil Sci 97(4), 290.Google Scholar
Volzone, C. & Cavalieri, A.L. (1996). Influence of smectites on magnetite pellet strengths. J Mater Sci Lett 15(17), 1532–1535.Google Scholar
Weiss, A. (1962). Neuere Untersuchungen über die Struktur thixotroper Gele. Rheologica Acta 2(4), 292–304.Google Scholar
Young, R., Templeton, T., Roussel, L.Y., Gestmann, I., van Veen, G., Dingle, T. & Henstra, S. (2008). Extreme high resolution SEM: A paradigm shift. Microsc Today 16(4), 24.Google Scholar
Zbik, M.S., Martens, W.N., Frost, R.L., Song, Y.F., Chen, Y.M. & Chen, J.H. (2008). Transmission X-ray microscopy (TXM) reveals the nanostructure of a smectite gel. Langmuir 24(16), 8954–8958.CrossRefGoogle ScholarPubMed