Hostname: page-component-78c5997874-mlc7c Total loading time: 0 Render date: 2024-11-18T20:06:46.310Z Has data issue: false hasContentIssue false
  • English
  • Français

The formation of corundum and aluminous hematite by the thermal dehydroxylation of aluminous goethite

Published online by Cambridge University Press:  09 July 2018

M. A. Wells ,
R. J. Gilkes  and
R. R. Anand
M. A. Wells
Affiliation:
Soil Science and Plant Nutrition, School of Agriculture, The University of Western Australia, Nedlands, WA 6009, Australia
R. J. Gilkes
Affiliation:
Soil Science and Plant Nutrition, School of Agriculture, The University of Western Australia, Nedlands, WA 6009, Australia
R. R. Anand
Affiliation:
Soil Science and Plant Nutrition, School of Agriculture, The University of Western Australia, Nedlands, WA 6009, Australia
Get access Rights & Permissions [Opens in a new window]

Abstract

Dehydroxylation of synthetic and natural goethites with a range of Al-substitution from 0–28 mole% was investigated with a view to predicting the behaviour of soil goethites heated by bush fires. Hematites formed at temperatures ≤ 500°C retain the initial Al-content of the precursor goethite up to a maximum of 28 mole% Al. Loss of Al from the hematite structure occurred at 700°C for synthetic hematites with levels of substitution ≥18 mole% Al, but no crystalline alumina phase was present. Crystallization of corundum occurred for synthetic Al-goethites with levels of substitution ≥18 mole% when heated at 900°C. Formation of corundum reduces the maximum level of Al-substitution in hematites to ∼ 12 mole%. The exsolved corundum occurs as aggregated, platy crystals, 40–45 nm in diameter, containing a maximum of 7 mole% Fe. Al-substituted maghemite (7 mole% Al) formed from high Al-goethites heated at 900°C. Although some corundum in soils may be produced by heating of aluminous goethite by fires, the absence of corundum in natural Al-goethites calcined at 900°C, and the very high temperature (900°C) at which corundum formed from synthetic goethite suggest that other sources of Al may be required as precursors for the corundum formed by heating of soils.

Type
Research Article
Information
Clay Minerals , Volume 24 , Issue 3 , September 1989 , pp. 513 - 530
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1989

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

Anand, R.R. & Gilkes, R.J. (1987a) Iron oxides in lateritic soils from Western Australia. J. Soil Sci., 38, 607–622.CrossRefGoogle Scholar
Anand, R.R. & Gilkes, R.J. (1987b) Variation in the properties of iron oxides within individual specimens of lateritic duricrust. Aust. J. Soil Res., 25, 287–302.Google Scholar
Anand, R.R. & Gilkes, R.J. (1987c) The association of maghemite and corundum in Darling Range laterites, Western Australia. Aust. J. Soil Res., 35, 303–311.Google Scholar
Brindley, G.W. (1980) Quantitative X-ray mineral analysis of clays. Pp. 412–438 in: Crystal Structures of Clay Minerals and their X-ray Identification (Brindley, G. W. & Brown, G., editors). Mineralogical Society, London.CrossRefGoogle Scholar
Brown, G. (1980) Associated minerals. Pp. 361–410 in: Crystal Structures of Clay Minerals and their X-ray Identification (Brindley, G. W. & Brown, G., editors). Mineralogical Society, London.Google Scholar
Campbell, A.S. & Schwertmann, U. (1984) Iron oxide mineralogy of placic horizons. Soil Sci,, 35, 569–582.Google Scholar
Chandler, C., Cheney, P., Thomas, P., Traband, L. & Williams, D. (1983) Fire effects on soil, water and air. Pp. 171–202 in: Fire and Forestry. John Wiley & Sons, New York.Google Scholar
Deer, W.A., Howie, R.A. & Zussman, J. (1%2) Rock-Forming Minerals, Vol. 5 Non-Silicates,, 371 pp. Longmans, London.Google Scholar
De Grave, E., Bowen, L.H. & Weed, S.B. (1982) Mossbauer study of aluminum substituted hematites. J. Magn. Magn. Mat., 27, 98–108.Google Scholar
Fysh, S.A. & Clarke, P.E. (1982) Aluminous hematite: A Mossbauer study. Phys. Chem. Miner., 8, 257–267.Google Scholar
Galbraith, S.T., Baird, T. & Fryer, J.R. (1979) Structural changes in β-FeO.OH caused by radiation damage. Acta Cryst. A365, 197–200.Google Scholar
Goodman, B.A. & Lewis, D.G. (1981) Mossbauer spectra of aluminous goethites (a-FeO.OH). Soil Sci., 32, 351–363.Google Scholar
Grubb, P.L.C. (1971) Mineralogical anomalies in the Darling Range bauxites at Jarrahdale, Western Australia. Econ. Geol., 66, 1005–1016.Google Scholar
Jackson, M., Tyler, S.A.. Willis, A.L., Bourbeau, G.A. & Pennington, R.P. (1948) Weathering sequence of clay-sized minerals in soils and sediments. J. Phys. Chem. Ithaca, 52, 1237–1260.Google Scholar
Kämpf, N. & Schwertmann, U. (1982a) The 5 m NaOH concentration treatment for iron oxides in soils. Clays Clay Miner., 30, 401–08.Google Scholar
Kämpf, N. & Schwertmann, U. (1982b) Quantitative determination of goethite and hematite in kaolinitic soils by X-ray diflfraction. Clay Miner., 17, 359–363.Google Scholar
Klug, H.P. & Alexander, L.E. (1974) X-ray Diffraction Procedures for Polycrystalline and Amorphous Materials, 2nd Ed.,, 966 pp. John Wiley & Sons. New York.Google Scholar
Lim-Nunez, R.S.L. (1985) Synthesis and acid dissolution of metal-substituted goethites and hematites. MSc thesis, The Univ. of Western Australia.Google Scholar
Lim-Nunez, R.S.L. & Gilkes, R.J. (1987) Acid dissolution of synthetic metal-containing goethites and hematites. Proc. Int. Clay Conf. Denvery, 197–204.Google Scholar
McKeague, J. A. & Day, J.H. (1%6) Dithionite- and oxalate- extractable Fe and A1 as aids in differentiating various classes of soils. Can. J. Soil Sci., 46, 13–22.Google Scholar
Muan, A. & Gee, C.L. (1955) Phase equilibrium studies in the system iron oxide-a-Al2O3 in air and at 1 Atm.02 pressure. J. Am. Ceram. Soc., 39, 207–214.Google Scholar
Nahon, D.C., Janot, C., Karoff, A.M., Paquet, H. & Tardy, Y. (1977) Mineralogy, petrography and structures, of iron crusts (ferricretes) developed on sandstones in the western part of Senegal. Geoderma, 19, 263–277.CrossRefGoogle Scholar
Norrish, K. & Rosser, H. (1983). Mineral phosphate. Pp. 335–361 in: Soils: An Australian Viewpoint CSIRO Aust. Div. of Soils, CSIRO Aust., Melbourne, Academic Press, London.Google Scholar
Norrish, K. & Taylor, R.M. (1961) The isomorphous replacement of iron by aluminium in soil goethites. Soil Sci., 12, 294–306.Google Scholar
Rooksby, H.P. (1961) Oxides and hydroxides of aluminium and iron. Pp. 354–392 in: The X-ray Identification and Crystal Structures of Clay Minerals, (Brown, G., editor). Mineralogical Society, London.Google Scholar
Schulze, D.G. (1984) The influence of aluminum on iron oxides. VIII. Unit-cell dimensions of Al-substituted goethites and estimation of A1 from them. Clays Clay Miner., 32, 36–44.Google Scholar
Schulze, D.G. & Schwertmann, U. (1984) The influence of aluminium on iron oxides. X. Properties of Al- substituted goethites. Clay Miner., 19, 521–539.Google Scholar
Schwertmann, U., Fitzpatrick, R.W. & Le Roux, J. (1977) Al-substitution and differential disorder in soil hematite. Clays Clay Miner., 25, 373–374.CrossRefGoogle Scholar
Schwertmann, U., Fitzpatrick, R.W., Taylor, R.M. & Lewis, D.G. (1979) The influence of aluminum on iron oxides. Part II. Preparation and properties of Al-substituted hematites. Clays Clay Miner., 27, 105–112.Google Scholar
Schwertmann, U. & Kämpf, N. (1985) Properties of goethite and hematite in kaolinitic soils of southern and central Brazil. Soil Sci., 139, 344–350.Google Scholar
Siradz, S.A. (1985) Distribution, properties and phosphorus requirements of soils of the Cobiac Valley, Darling Range, Western Australia. MSc Thesis, The Univ. of Western Australia.Google Scholar
Thiel, R. (1963) Zum system a-FeO.OH-y-Al O.OH. Z, Anorg. AUg. Chem., 326, 70–78,Google Scholar
Watari, F., Delavignette, P., Van Lunduyt, J. & Amelinckx, S. (1983) Electron microscopic study of dehydration transformations. III. High resolution observation of the reaction process FeO.OH->Fe2O3- J. Solid State Chem., 48, 49–64.Fe2O3-+J.+Solid+State+Chem.,+48,+49–64.>Google Scholar