Adsorption mechanisms and effects of thiocarbamate collectors in the separation of chalcopyrite from pyrite minerals: DFT and experimental studies

Mkhonto, Peace P.; Zhang, Xingrong; Lu, Liang; Xiong, Wei; Zhu, Yimin; Han, Long; Ngoepe, Phuti E.

doi:10.1016/j.mineng.2021.107318

Cited by 46 publications

(21 citation statements)

References 39 publications

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“…The unreconstructed and reconstructed surface energies of the relaxed slabs (( E Surf. R )) were also computed using eq 2 , 30 , 52 , 53 similar to eq 1 where ( E Slab. R ) is the total energy of the unrelaxed slab, E Bulk/atom is the energy of the bulk per number of atoms, n is the number of atoms in the slab, and A is the surface area multiplied by 2 to account for the top and bottom surface areas.…”

Section: Computational Methodsmentioning

confidence: 99%

“…Computational methods have been widely used to investigate a wide range of minerals, including pyrite; , chalcopyrite; , pentlandite; − sperrylite, pentlandite, and platinum; and sperrylite and platarsite . These also include the reconstruction of different surfaces, , oxidation mechanism, − and separation of minerals. , Nevertheless, there is no computational study that investigated the cooperite surfaces. Surface studies are one of the most important methods to understand the chemical behavior and reactivity of minerals that can be applicable to their recovery.…”

Section: Introductionmentioning

confidence: 99%

“… 23 These also include the reconstruction of different surfaces, 24 , 25 oxidation mechanism, 26 − 29 and separation of minerals. 30 , 31 Nevertheless, there is no computational study that investigated the cooperite surfaces. Surface studies are one of the most important methods to understand the chemical behavior and reactivity of minerals that can be applicable to their recovery.…”

Section: Introductionmentioning

confidence: 99%

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Reconstruction of Cooperite (PtS) Surfaces: A DFT-D+U Study

Mkhonto

Ngoepe

2022

ACS Omega

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Cooperite (PtS) is one of the main sources of platinum in the world and has not been given much attention, in particular from the computational aspect. Besides, the surface stability of cooperite is not fully understood, in particular the preferred surface cleavage. In the current study, we employed computer modeling methods within the plane-wave framework of density functional theory with dispersion correction and the U parameter to correctly predict the bulk and surface properties. We reconstructed and calculated the geometries and surface energies of (001), (100), (101), (112), (110), (111), and (211) cooperite surfaces of stoichiometric planes. The Pt d-orbitals with U = 4.5 eV and S p-orbitals with U = 5.5 eV were found optimum to correctly predict a band gap of 1.408 eV for the bulk cooperite model, which agreed with an experimental value of 1.41 eV. The PtS-, Pt-, and S-terminated surfaces were investigated. The structural and electronic properties of the reconstructed surfaces were discussed in detail. We observed one major mechanism of relaxation of cooperite surface reconstructions that emerged from this study, which was the formation of Pt–Pt bonds. It emanated that the (110) and (111) cooperite surfaces underwent significant reconstruction in which the Pt2+ cation relaxed into the surface, forming new Pt–Pt (Pt2 2+) bonds. Similar behavior was perceived for (101) and (211) surfaces, where the Pt2+ cation relaxed inward and sideways on the surface, forming new Pt–Pt (Pt2 2+) bonds. The surface stability decreased in the order (101) > (100) ≈ (112) > (211) > (111) > (110) > (001), indicating that the (101) surface was the most stable, leading to an octahedron cooperite crystal morphology with truncated corners under equilibrium conditions. However, the electronic structures indicated that the chemical reactivity stability of the surfaces would be determined by band gaps. It was found that the (112) surface had a larger band gap than the other surfaces and thus was a chemical stability competitor to the (101) surface. In addition, it was established that the surfaces had different reactivities, which largely depended on the atomic coordination and charge state based on population atomic charges. This study has shown that cooperite has many planes/surface cleavages as determined by the computed crystal morphology, which is in agreement with experimental X-ray diffraction (XRD) pattern findings and the formation of irregular morphology shapes.

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Section: Computational Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reconstruction of Cooperite (PtS) Surfaces: A DFT-D+U Study

Mkhonto

Ngoepe

2022

ACS Omega

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“…More recent studies have included computational analyzes like density functional theory (DFT) to complement experimental tests. Mkhonto et al [ 51 ] investigated the adsorption mechanisms of O -isopropyl- N -ethyl-thionocarbamate (IPETC), O -isopropyl- N -diethyl-thionocarbamate (IPDETC), and S -allyl- N -diethyl-dithiocarbamate (ADEDTC) on chalcopyrite reconstructed (1 1 2) surface and pyrite (1 0 0) surface. The obtained information was very interesting, since the experimental microflotation studies were linked with fundamental explanations from DFT.…”

Section: Chalcopyrite Flotation Collectorsmentioning

confidence: 99%

Froth Flotation of Chalcopyrite/Pyrite Ore: A Critical Review

et al. 2022

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In the present work an intense bibliographic search is developed, with updated information on the microscopic fundamentals that govern the behavior of flotation operations of chalcopyrite, the main copper mineral in nature. In particular, the effect caused by the presence of pyrite, a non-valuable mineral, but challenging for the operation due to its ability to capture a portion of collector and float, decreasing the quality of the concentrate, is addressed. This manuscript discusses the main chemical and physical mechanisms involved in the phenomena of reagent adsorption on the mineral surface, the impact of pH and type of alkalizing agent, and the effect of pyrite depressants, some already used in the industry and others under investigation. Modern collector reagents are also described, for which, although not yet implemented on an industrial scale, promising results have been obtained in the laboratory, including better copper recovery and selectivity, and even some green reagents present biodegradable properties that generate a better environmental perspective for mineral processing.

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“…At present, multitude depressants have been studied to regulate the flotation behaviour of pyrite during the multimetal sulfide minerals beneficiation. It mainly includes inorganic depressants, organic depressants and two or more of combination (Mu et al, 2016a(Mu et al, , 2016b). Among of them, lime (CaO), as an inorganic depressant exhibits relatively superior inhibition effects on pyrite in a high alkali lime craft (at extremely high pH˃11) (Ding et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

The depression mechanism on pyrite in a low-alkaline system with combined depressants: Experiment, HSC, DFT and ToF–SIMS studies

Li¹,

Yuan²,

Ding³

et al. 2023

Physicochem. Probl. Miner. Process.

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Depression of pyrite in a low-alkaline system has sparked soaring interests for the multi-metal sulfide minerals flotation recently. This study investigates effects of combined depressants (Ca(ClO)2 and CaO) on pyrite flotation with butyl xanthate (KBX). Micro-flotation experiments indicate that the addition of 200 mg/L combined depressants (a mass ratios of CaO to Ca(ClO)2 of 2:3) and 1.0×10−3 mol/L KBX at pH 9.5 can effectively depresses the flotation of pyrite, and a minimum pyrite recovery rate of 12.5% is obtained. Basic thermodynamic evaluation results confirm the participation of Ca(ClO)2 significantly decrease the negative Gibbs free energies of pyrite oxidation reaction. Besides, the calcium species (Ca(OH)2, Ca2+ and Ca(Cl)2) will spontaneously transform into CaCO3, and it is the ultimate dominant calcium species in the CO32- system. Density functional theory (DFT) results indicate that CaCO3 can chemically adsorb onto the pyrite surface with an adsorption energy of –671.13 kJ/mol. The O1 and Ca atoms mainly contribute to the bonding process and are responsible for the stable adsorption of CaCO3. ToF-SIMS results provide strong evidence that the combined depressants increase the amount of hydrophilic species and decrease dixanthogen adsorption onto the pyrite surface. The thickness of the whole formed hydrophilic species is approximately 50 nm. Semiquantitative amounts of hydrophilic species follow the order of hydroxy calcium>iron carbonyl>calcium carbonate. Overall, hydrophilic species repulse adsorption of dixanthogen and significantly reduce the flotation performance of pyrite.

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Adsorption mechanisms and effects of thiocarbamate collectors in the separation of chalcopyrite from pyrite minerals: DFT and experimental studies

Cited by 46 publications

References 39 publications

Reconstruction of Cooperite (PtS) Surfaces: A DFT-D+U Study

Reconstruction of Cooperite (PtS) Surfaces: A DFT-D+U Study

Froth Flotation of Chalcopyrite/Pyrite Ore: A Critical Review

The depression mechanism on pyrite in a low-alkaline system with combined depressants: Experiment, HSC, DFT and ToF–SIMS studies

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