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Rapid dehydroxylation of nickeliferous goethite in lateritic nickel ore; X-ray diffraction and TEM investigation

Landers, Matthew ; Gilkes, Robert J ; Wells, Martin A

Clays and clay minerals, 2009-12, Vol.57 (6), p.751-770 [Periódico revisado por pares]

Cham: Clay Minerals Society

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  • Título:
    Rapid dehydroxylation of nickeliferous goethite in lateritic nickel ore; X-ray diffraction and TEM investigation
  • Autor: Landers, Matthew ; Gilkes, Robert J ; Wells, Martin A
  • Assuntos: Biogeosciences ; chemical properties ; clay mineralogy ; clay minerals ; Dehydroxylation ; Earth and Environmental Science ; Earth Sciences ; Earth, ocean, space ; Economic geology ; Exact sciences and technology ; experimental studies ; Geochemistry ; Goethite ; hematite ; iron oxides ; kaolinite ; laterites ; Lateritic ; Medicinal Chemistry ; metal ores ; mineral deposits, genesis ; Mineralogy ; Nanoscale Science and Technology ; Ni Ore ; nickel ores ; oxides ; rock, sediment, soil ; sed rocks, sediments ; Sedimentary petrology ; sheet silicates ; Shock Heating ; Silicates ; Soil Science & Conservation ; soils ; substitution ; supergene processes ; TEM ; TEM data ; X-ray diffraction data ; XRD
  • É parte de: Clays and clay minerals, 2009-12, Vol.57 (6), p.751-770
  • Notas: 0009-8604(20091201)57:6L.751;1-
    (QE) Geology
    ObjectType-Article-2
    SourceType-Scholarly Journals-1
    ObjectType-Feature-1
    content type line 23
  • Descrição: A method for extracting Ni and other metals from lateritic ores by means of shock heating has been investigated. Shock heating releases some of the metal from its goethitic host. Even though the transformation of pure goethite to hematite is known to occur via intermediate hydroxylated phases, the effect of other metals such as Ni substituting for Fe in goethites on this thermal transformation to hematite is unknown. The purpose of this study was to fill this gap, with the hope that the results will lead to more energy-efficient extraction methods and/or a better understanding of Fe geochemistry in thermally activated soils. X-ray diffraction, transmission electron microscopy with EDS, and thermal analysis were used to investigate mineralogical changes in nickeliferous goethites from five oxide-type lateritic nickel ore deposits that had been subjected to shock heating at temperatures in the range 220-800°C. Acicular, nano-sized goethite was the main constituent of the samples with minor to trace amounts of quartz, talc, kaolinite, chromite, maghemite, and Mn oxides. Goethite was partially dehydroxylated to OH-hematite at 340-400°C and had completely altered to well ordered hematite at 800°C. The OH-hematite was characterized by broad XRD peaks for reflections associated with the Fe sublattice. The goethite unit-cell a and b lengths remained almost constant with increasing preheating temperature up to 300°C, while the size of the c axis dimension contracted. The neoformed hematite crystals were larger than the precursor goethite crystals due to development, by sintering and surface diffusion, of regularly ordered hematite domains. The increase (1.5-2.6 fold) in surface area with increasing heating temperature (up to 340-400°C) reflected the development of slit-shaped micropores (∼300°C), which further developed into elliptically shaped micropores (∼400°C) in OH-hematite. With increased heating temperature, well ordered hematite formed with only a few micropores remaining. Such results may contribute to the development of more efficient procedures for extracting Ni from lateritic nickel ores, as the rate of dissolution of goethite in acid in "heap and pressure" leach facilities will be enhanced by the increases in surface area and microporosity. The results may also provide valuable information on the probable effects of natural heating on pedogenic Fe oxides.
  • Editor: Cham: Clay Minerals Society
  • Idioma: Inglês;Chinês
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