7-11 July 2014
Africa/Johannesburg timezone
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Electronic structures of oxygen adsorption on {110} nickel-rich pentlandite (Fe4Ni5S8) mineral surface

Presented by Mr. Peace Prince MKHONTO on 9 Jul 2014 from 17:10 to 19:00
Type: Poster Presentation
Session: Poster2
Track: Track A - Division for Physics of Condensed Matter and Materials
Board #: A.204

Abstract

Pentlandite (Co,Fe,Ni)<sub>9</sub>S<sub>8</sub> is the most abundant iron-nickel sulphide ore containing mineral and has a wide range of applications in industries. The mineral is of commercial importance and can be extracted using floatation processes; one of the processes is oxidation. The oxidation plays a significant role in forming air bubbles that float the pentlandite mineral. Despite reports that oxidation tend to depress the sulphide minerals, it has good preferential oxidation of iron. The present study investigated the clean and oxidised nickel-rich {110} pentlandite surface using ab-initio density functional theory (DFT). The Bader analysis have been evaluated for clean and oxidized surfaces and suggests that both Fe and Ni have 2+ and 3+ oxidation state, respectively. Furthermore, when oxygen is adsorbed at the (fcc hallow site, on Fe-top site) and on Ni-top site, it was found that the {110} pentlandite surface oxidises as (Fe-O-Fe) and Ni-O-O, respectively. Oxidation had also shown preferential oxidation of iron and we noted a charge transfer from the metals to the oxygen molecule. We also observed that the oxygen (O1) coordinated to the Fe accepts electrons to σ<sub>s</sub> and Π<sub>p</sub> bonding orbitals, while the oxygen (O2) coordinated to O1 only occupies the Π<sub>p</sub><sup>*</sup> antibonding for the fcc hallow site and Fe-top site adsorption. The Ni-top site adsorption is observed to occupy similar to the just mentioned case however, we noted that the Π<sub>p</sub><sup>*</sup> antibonding orbital is occupied on O1 atom. This study gives an understanding of oxidation of pentlandite naturally and during flotation.

Award

yes

Level

MSc

Supervisor

Prof P.E. Ngoepe, phuti.ngoepe@ul.ac.za , University of Limpopo

Paper

yes

Place

Room: D Ring ground level


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