Thermal upgrading of nickeliferous pyrrhotite tailings: Formation mechanism of ferronickel alloy

Liu, F.; Yu, Dawei; Marcuson, Sam; Wang, Fanmao; Li, Bo; Barati, Mansoor

doi:10.1016/j.mineng.2019.02.006

Cited by 11 publications

(1 citation statement)

References 13 publications

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“…However, the relationship between sulfide oxidation and their electronic structures is still in development due to insufficient understanding of the steps involved in the sulfide oxidation process. In this study, pyrrhotite, Fe (1−x) S (0 < x ≤ 0.2), a major nonstoichiometric iron sulfide gangue mineral in Ni−Cu ores 6 and a major contributor to acid mine drainage, 7 was studied to reveal the relationship between its electronic structures and oxidation.…”

Section: Introductionmentioning

confidence: 99%

Unraveling Polymorphic Pyrrhotite Electrochemical Oxidation by Underlying Electronic Structures

Khalkhali

Grundy

et al. 2019

J. Phys. Chem. C

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Metal sulfide oxidation is a common, yet poorly understood, phenomenon that significantly affects surface properties. In this paper, we studied the electrochemical oxidation of polymorphic pyrrhotites (Fe 1−x S) to gain insights into the relationship between their electrochemical oxidation rate and electronic structures. Surface composition of oxidized pyrrhotites, as shown by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS), suggested that one key step for pyrrhotite oxidation is the outward diffusion of metal cations to form polysulfide and oxides. This diffusion process involves the rupture of Fe−S bonds and, hence, depends on the Fe−S bond strength. According to the ToF-SIMS, the Fe−S bond strength in the defective layer (>100 nm), the layer right underneath the polysulfide layer (∼20 nm), was modified by the incorporation of oxygen atoms, which mainly existed in the form of OH − and H 2 O. It was found that oxygen anions are much more abundant in the defective layer of monoclinic pyrrhotite (Fe 7 S 8 ) than that of hexagonal pyrrhotite (Fe 9 S 10 ), resulting in a much weaker Fe−S bond with the former than the latter. The oxygen abundance difference can be explained by their electronic structures. Density functional theory (DFT) calculation showed that monoclinic pyrrhotite (Fe 7 S 8 ) get a higher Fe 3d and S 3p band center than hexagonal pyrrhotite (Fe 9 S 10 ). Therefore, monoclinic pyrrhotite could incorporate oxygen atoms easier than hexagonal pyrrhotite. This presented a clear relation between polymorphic pyrrhotite electronic structures and their electrochemical oxidation rate and also fundamentally explained why the sulfides with a slight bulk metal−sulfur bond strength difference could demonstrate a significant oxidation rate difference.

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Section: Introductionmentioning

confidence: 99%

Unraveling Polymorphic Pyrrhotite Electrochemical Oxidation by Underlying Electronic Structures

Khalkhali

Grundy

et al. 2019

J. Phys. Chem. C

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Ni Recovery from Nickeliferous Pyrrhotite Concentrates via a Thermal Concentration Process: Effects of Heat Treatment Time

Liu

Barati

2020

The Minerals, Metals &Amp; Materials Series

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Thermal Upgrading of Nickeliferous Pyrrhotite Tailings for the Recovery of Nickel in the Form of Ferronickel Alloy

Liu

Zhang

et al. 2019

Metall Mater Trans B

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Production of ferronickel alloy by thermal treatment of nickeliferous pyrrhotite (Pyrr) tailings was studied by both thermodynamic assessment and experimentation. It was demonstrated that Ni can be extracted from Pyrr by increasing the Fe/S ratio of the material, which was achieved by either partial oxidation of Pyrr followed by H 2 reduction or in situ generation of metallic Fe from the reduction of magnetite by petroleum coke pre-mixed with Pyrr. Examination of the samples produced from thermal treatment at 1173 K demonstrated that both approaches were effective in generating ferronickel, although the size of the particles was suboptimal for subsequent separation. Increasing the ferronickel particle size could be achieved by a smelting step at 1473 K, forming a sulfur-deficient molten matte. Slow cooling of the molten matte resulted in precipitation, settling, and growth of ferronickel alloy particles.

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Thermal upgrading of nickeliferous pyrrhotite tailings: Formation mechanism of ferronickel alloy

Cited by 11 publications

References 13 publications

Unraveling Polymorphic Pyrrhotite Electrochemical Oxidation by Underlying Electronic Structures

Unraveling Polymorphic Pyrrhotite Electrochemical Oxidation by Underlying Electronic Structures

Ni Recovery from Nickeliferous Pyrrhotite Concentrates via a Thermal Concentration Process: Effects of Heat Treatment Time

Thermal Upgrading of Nickeliferous Pyrrhotite Tailings for the Recovery of Nickel in the Form of Ferronickel Alloy

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