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Genetic model of the black shale hosted PGE-gold Sukhoi Log deposit (Russia)
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
All the metals have fairly similar evolution in their mineralogy. In the early stage most of them were deposited as native metals or intermetallic compounds. Their sulfosalts were then precipitated, followed finally by sulfides. The native metal assemblage includes native gold of high fineness, native platinum, and Pt-Fe-Cu solid solutions, as well as such exotic minerals as native chromium, iron, and tungsten, and solid solutions of Sn-Sb, Ni-Sb, and others. The native metal paragenetic stage developed under highly reducing conditions. Its duration was comparatively short within the whole ore-forming process, most of which was controlled by the sulfur activity. This control can be well illustrated by the sequence of mineral deposition in the Fe-Ni-S system. The compositions of minerals of the pyrrhotite group varied from S-poor troilite to S-rich monoclinic pyrrhotite. The former was observed in mineral assemblage with Fe pentlandite; the latter - with Ni-pentlandite. The Ni-pentlandite occurs in equilibrium with millerite, heazlewoodite, and thiospinels. In the mentioned sequence, pyrite is the latest mineral hosting relict inclusions of all other minerals.
Muonionalustaite, Ni3(OH)4Cl2·4H2O, a new mineral formed by terrestrial weathering of the Muonionalusta iron (IVA) meteorite, Pajala, Norrbotten, Sweden
Published in GFF, 2021
Dan Holtstam, Luca Bindi, Andreas Karlsson, Johan Söderhielm, Anders Zetterqvist
Meteorites are particularly prone to weathering compared to most terrestrial rocks. The rate and the secondary products of post-fall alteration are determined by properties of the meteorite itself and climatic and environmental conditions on Earth. In particular, metal-rich meteorites tend to deteriorate mainly due to Fe oxidation (aerobic corrosion; e.g., White et al. 1967; Golden et al. 1995; Bland et al. 2006). Besides atmospheric oxygen, the presence of water and chlorine effectively promotes alteration (Buchwald & Clarke 1989; Lee & Bland 2004). Predominant minerals produced are Fe (±Ni) oxides and hydroxides: akaganeite, goethite, hematite, lepidocrocite, maghemite and magnetite. In addition, a variety of Fe- and/or Ni-bearing minerals of other mineral classes have been reported from modified iron – stony-iron meteorites (e.g., Rubin 1997): sulphides (e.g., pentlandite, heazlewoodite), carbonates (siderite, reveesite, hellyerite), halides (nickelbischofite, droninoite), sulphates (retgersite, honessite, nickelhexahydrite), phosphates (vivianite, cassidyite, arupite), and a silicate (pecoraite). Essential chemical components for the secondary minerals are derived both from meteorite (Fe, Ni, S and P) and from the terrestrial environment (O, H, Cl, C and Si).
Controls on cobalt and nickel distribution in hydrothermal sulphide deposits in Bergslagen, Sweden - constraints from solubility modelling
Published in GFF, 2020
The solubility fields for both Co and Ni sulphide minerals (cattierite, linnaeite and Co-pentlandite for Co, and bensienite, millerite and heazlewoodite for Ni) expand significantly in oxidized fluids in equilibrium with hematite. Under these conditions, transport of Co and Ni is possible even in near-neutral fluids in equilibrium with calcite and K-feldspar. Still, whereas Co is soluble at any pH at 150° C, Ni is insoluble at pH above 7. Deposition of Co and Ni sulphides under near-neutral conditions could result from a decrease in log ƒO2, triggering reduction of brine SO42- or by mixing with externally derived H2S.
The Direct Leaching of Nickel Sulfide Flotation Concentrates – A Historic and State-of-the-Art Review Part III: Laboratory Investigations into Atmospheric Leach Processes
Published in Mineral Processing and Extractive Metallurgy Review, 2022
Nebeal Faris, Mark I. Pownceby, Warren J. Bruckard, Miao Chen
Malkhuuz (2006) studied the dissolution of individual nickel sulfide minerals (millerite, violarite, and heazlewoodite) in HCl-MgCl2 solutions. Among the nickel sulfides studied, heazlewoodite was found to be the most easily leached at all acid concentrations studied (1–10 molal). Millerite and violarite were found to be refractory over an acid concentration range of 1–6 molal though 56.7% of the contained Ni in millerite was dissolved in 10 molal HCl at 60°C. The leaching behavior of two different nickel sulfide concentrates in HCl-MgCl2 was also studied by Malkhuuz (2006). The best leaching results with respect to Ni and Co extraction for both concentrates were achieved after leaching for 1 to 2 hours at 100°C in 6 to 8 molal HCl plus 2 molal MgCl2 with 95% of the Ni and 75–76% Co being extracted. Characterization of leach residues via XRD under optimal leaching conditions for Ni showed that the residues consisted of pyrite, talc, and quartz, which were inert during leaching; pyrite inertness, however, could be an issue if it were a major host for cobalt, which might explain the lower Co extractions observed by Malkhuuz (2006). Malkhuuz (2006) found that CuCl2 and FeCl3 were not beneficial toward sulfide leaching due to reaction of Cu(II) and Fe(III) ions with H2S to form passivating layers on the particle surfaces; copper enrichment on particle surfaces in leach residues was observed by SEM-EDX which could support the theory for Cu(II) inhibition due to sulfide precipitation. van Weert, Mah, and Piret (1974) found ferric ions had an inhibitory effect during non-oxidative dissolution of nickeliferous pyrrhotite concentrates but was cautious in ascribing this to the formation of elemental sulfur on the particle surface given that no elemental sulfur layer could be detected by EPMA. Filmer and Balestra (1981) whose work is described in more detail later have shown that non-oxidative dissolution of sulfides is dependent on the sulfur-to-metal stoichiometric ratio at the reaction interface and found that concentrates low in sulfur produce a more cathodic mixed potential in hydrochloric acid and are therefore more reactive. This would suggest that the inhibition in non-oxidative dissolution in the presence of ferric ions observed by van Weert, Mah, and Piret (1974), Harris et al. (2004), and Malkhuuz (2006) could possibly be due to ferric ions leaching metals from the sulfide particle surface thus producing a metal-deficient sulfide layer, resulting in a shift toward an anodic potential and reduced reactivity in hydrochloric acid.