New insights into nanomineralogy and geochemistry of Ni-laterite ores from central Greece (Larymna and Evia deposits)

Michail Samouhos*, Athanasios Godelitsas, Chrysanthi Nomikou, Maria Taxiarchou, Petros Tsakiridis, Janez Zavašnik, Platon N. Gamaletsos, Athanasios Apostolikas

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Nickeliferous laterite ores from two typical central Greece deposits (Larymna and Evia), currently used in the LARCO GMMSA smelting plant to produce ferronickel, were characterized using a combination of diffraction, microscopic, and analytical techniques. X-ray diffraction patterns of various fractions, with emphasis to the clayey material (< 2 μm), after glycolation and heating at 550 °C, indicated that both materials contain crystalline Fe3+ oxide (hematite) and chlorite-group phyllosilicates, whereas the Evia sample contains additional illite. Transmission electron microscopy investigations revealed that the LARCO laterite ores consist of complex nanoscale aggregates of the above-mentioned phases. Different Ni-bearing Mg-Fe-phyllosilicates (mainly chlorite-group minerals), occur in mixture with hematite. Nickel is present in all examined phases, and therefore the separation of pure Ni-phases, by physical or chemical methods, is practically unfeasible. Trace element bulk analyses showed that there no significant differences, with regarding to Ni content concentrations (ca. 0.6–0.7 wt.%), between the initial ore and the clay fraction, for both the Larymna and Evia laterites (ca. 30% and 26% wt.% enrichment respectively). However, the Larymna ore contains double quantities of Co and it is enriched in rare earths compared to Evia (ΣREE = 774 ppm and 76 ppm respectively), while Sc concentrations are comparable in both mining areas (64 ppm and 42 ppm respectively). Discrimination diagrams (e.g. Th/Sc vs. Zr/Sc and Ce/Ce* vs. Eu/Eu*) showed that LARCO laterite Ni-ores do not exclusively originate in ultrabasic -ophiolitic- rocks as previously considered.
Original languageEnglish
JournalChemie der Erde
Volume79
Issue number2
Pages (from-to)268-279
ISSN0009-2819
DOIs
Publication statusPublished - 2019

Keywords

  • Geophysics
  • Geochemistry and Petrology
  • Clays
  • Laterite ore
  • Mineral nanoparticles
  • Nickel
  • Phyllosilicates
  • Rare earth elements

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