Multi-scale investigation applied to Ni laterite ore deposits : Impact of discrete fractures on Ni mineralization

AbstractIntegrating structural control on mineralisation and geochemical ore-forming processes is crucial when studying deformed ore deposits. Yet, structural and geochemical data are rarely acquired at the same scale: structural control on mineralisation is typically investigated from the district to the deposit and macroscopic scales whereas geochemical ore processes are described at the microscopic scale. The deciphering of a deformation-mineralisation history valid at every scale thus remains challenging.This study proposes a multi-scale approach that enables the reconciliation of structural and geochemical information collected at every scale, applied to the example of the Galat Sufar South gold deposit, Nubian shield, northeastern Sudan. It gathers field and laboratory information by coupling a classical petrological-structural study with high-resolution X-ray computed tomography, electron back-scattered diffraction and laser ablation inductively-coupled plasma mass spectrometry on mineralised sulphide mineral assemblages.This approach demonstrates that there is a linear control on mineralisation expressed from the district to microscopic scales at the Galat Sufar South gold deposit. We highlight the relationships between Atmur-Delgo suturing tectonics, micro-deformation of sulphide minerals, syn-pyrite recrystallisation metal remobilisation, gold liberation and ore upgrading. Our contribution therefore represents another step forward a holistic field-to-laboratory approach for the study of any other sulphide-bearing, structurally-controlled ore deposit type.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5635726

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A Thermodynamic Study of the Reduction of a Limonitic Laterite Ore by Methane

High Temperature Materials and Processes ◽

10.1515/htmp-2017-0106 ◽

2018 ◽

Vol 37 (9-10) ◽

pp. 909-919

Author(s):

C. A. Pickles ◽

W. Anthony

Keyword(s):

Nickel Oxide ◽

Carbon Dioxide Emissions ◽

Ore Deposits ◽

Reducing Agent ◽

Thermodynamic Study ◽

Nickel Recovery ◽

Sulphide Ore ◽

Laterite Ores ◽

Thermodynamic Simulations ◽

Laterite Ore

AbstractThe recovery of nickel from the oxidic nickeliferous laterite ores is receiving increasing attention due to the difficulty of recovering this metal from the sulphide ore deposits. One possible solution is to selectively reduce the nickel oxide in the ore, which could then be upgraded by, for example, magnetic concentration. In this article, a thermodynamic study was performed on the reduction of a limonitic laterite ore by methane. Methane was selected as the reducing agent as it has a lower environmental impact than carbon due to the reduced carbon dioxide emissions. The effects of temperatures and methane additions on the nickel recovery and nickel grade were investigated. High recoveries of over 95 % were predicted, but the grades were limited to about 2.5 % due to the formation of magnetite. The thermodynamic simulations for reduction by methane were in agreement with the experimental results in the literature for other reducing agents, reflecting the fact that the nickel oxide in the limonitic ore is relatively unstable. Thus, high recoveries could be achieved irrespective of the reducing agent involved.

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Incorporation of Cr, Mn and Ni into goethite (α-FeOOH): mechanism from extended X-ray absorption fine structure spectroscopy

Clay Minerals ◽

10.1180/000985502374066 ◽

2002 ◽

Vol 37 (4) ◽

pp. 639-649 ◽

Cited By ~ 29

Author(s):

Balwant Singh ◽

D. M. Sherman ◽

R. J . Gilkes ◽

M. A. Wells ◽

J . F. W. Mosselmans

Keyword(s):

Transition Metals ◽

Ore Deposits ◽

Isomorphous Substitution ◽

Surface Complexes ◽

Coordination Environment ◽

X Ray ◽

Chemical Mechanisms ◽

Local Coordination ◽

X Ray Absorption ◽

Laterite Ore

AbstractThe crystal-chemical mechanisms by which transition metals are associated with goethite are fundamental to our understanding of the solubility and bioavailability of micronutrients and heavy metals in soils, and in the formation of laterite ore deposits. Transition metals such as Cr, Mn and Ni may sorb onto goethite by forming surface precipitates, surface complexes or by replacing Fe3+ in the goethite structure. In the work reported here, we investigated the local coordination environment of Cr, Mn and Ni in synthetic goethite using EXAFS spectroscopy. We demonstrate the isomorphous substitution for Fe3+ by Cr3+ (up to 8 mol.%), Mn3+ (up to 15 mol.%) and Ni2+ (up to 5 mol.%). We find, however, that the next-nearest-neighbour coordination environment changes with composition. The perturbations are likely to be responsible for limiting the accommodation of Cr3+, Mn3+ or Ni2+ in the FeOOH structure.

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