The surface state of hematite and its wetting characteristics

Shrimali, Kaustubh; Jin, Jiaqi; Hassas, Behzad Vaziri; Wang, Xuming

doi:10.1016/j.jcis.2016.05.030

Cited by 96 publications

(43 citation statements)

References 45 publications

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“…The Zeta potentials of aegirite and specularite at different pH values were measured, and the result is illustrated in Figure 8. As shown in Figure 8, the Zeta potentials of these two minerals both decreased with the increase of pH value, and the IEP of specularite (2.83) is higher than that of aegirite (2.12), which conforms to the conjecture and previous results [11,40]. As a cationic collector, DDA increases the surface potential when adsorbed on a mineral surface.…”

Section: Surface Charge Of Mineral Surfacesupporting

confidence: 89%

Surface Properties and Floatability Comparison of Aegirite and Specularite by Density Functional Theory Study and Experiment

Gao

et al. 2019

Minerals

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Understanding the differences in surface properties between aegirite and specularite is of great significance to study their separation. In this work, the surface properties of aegirite and specularite, as well as their relationships to floatability, have been explored by first principle calculation, flotation, and Zeta potential measurement. The surface relaxation indicated that the specularite (001) surface appeared to show more surface reconstruction. The unsatisfied bond properties, Mulliken bond population, and surface charge showed that the floatability of specularite was superior to that of aegirite. The flotation results showed that the hydrophobicity of specularite was higher than that of aegirite with dodecylamine (DDA) as the collector. It is infeasible to separate specularite from aegirite by flotation using starch as the depressant, and research of effective reagents with high affinity to the element Si is the subclinical breakthrough point of specularite/aegirite separation.Minerals 2019, 9, 782 2 of 15 flotation with amines. They also found that starch was not a selective depressant for magnetite in the process of the reverse cationic flotation of iron ores when iron-containing silicates as amphiboles are present in the flotation system [8]. Carboxymethyl cellulose, an effective depressant for iron oxide, was also found to be a depressant for chlorite [14].The novel high-efficiency depressants or collectors are considered to be an effective method to solve the unsatisfactory separation problems [15,16]. These depressants and collectors are targeted for making a sufficient hydrophilic and hydrophobic state of the mineral and gangue surface, respectively. Therefore, they are profoundly inseparable from understanding the surface properties of the minerals in the novel depressant or collector molecule design and their adsorption mechanism on the mineral surface.In recent years, with the rapid developments of theoretical and computational chemistry, a density functional theory (DFT) calculation can be adopted to visually investigate the surface properties and floatability of minerals and to predict possible novel reagents [4,17]. The wettability of the mineral surface and its regulation have always been the core issues of the flotation process [18][19][20]. Thus, further research of the nature of the cleavage surface, especially of the main cleavage surface, is of great significance for investigating the floatability of the minerals. For example, Han et al. [21] calculated the surface properties of the hemimorphite (110) surface and the simthsointe (101) surface by the first-principle calculation method to investigate their relationships to the mineral floatability, which implied that hemimorphite (110) surface is more readily wetted by water, while the O atoms on hemimorphite (110) surface are more impeding of collector molecules. He et al. [22] calculated the properties of spodumene and revealed that the O atoms in spodumene are the most active, while the Li atoms are inactive, so an activator is nece...

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Section: Surface Charge Of Mineral Surfacesupporting

confidence: 89%

Surface Properties and Floatability Comparison of Aegirite and Specularite by Density Functional Theory Study and Experiment

Gao

et al. 2019

Minerals

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“…The magnetite behaves almost as an electrical metallic conductor, while the hematite phase displays electrical insulating property [6]. As examples, hematite can be used as an anode for a lithium-ion battery [13] or for photoelectrochemical water splitting [14], as pigment [15] [16] [17], in waste water treatment [18], 3 as a gas sensor [19] [20], or in catalysis [21]. Magnetite can be employed in biomedical [22] [23], magnetic printing [24] [25], in microelectronics as a microwave-absorbing materials [26][27] [28] [29], in thermoelectricity [30], or as a thermistor in a bolometer [31].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of iron oxide films by reactive magnetron sputtering assisted by plasma emission monitoring

Aubry

Liu

Dekens

et al. 2019

Materials Chemistry and Physics

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Iron oxide films were synthesized by pulsed-DC magnetron sputtering from a metallic target in Ar and O2 gas mixtures. Plasma emission monitoring was implemented to accurately control the metalto-oxygen ratio in the coating through the chemical state of the iron target. The intensity of the Fe* emission line was maintained at a given value (setpoint) in regulating the introduced oxygen flow rate. In addition, the oxidation rate of the growing film was adjusted by controlling the oxidationto-deposition rate ratio as a function of the position of the substrates relative to the magnetron axis.The iron oxide films were characterized by X-ray diffraction, UV-VIS spectrophotometry, electrical measurement and vibrating sample magnetometry. In addition to the crystallization of 2 pure hematite and magnetite phases, both phases coexist in a transition domain for a short range of setpoint depending on the oxidation-to-deposition rate ratio. The electrical, optical and magnetic behaviors of the FeOx films suggest that the relative proportion of phases can be tailored in this range. The FeOx film behaviors can then be tuned from the hematite semi-conductor properties to the semi-metallic magnetite properties.

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“…Then, the substrate wafer was manually polished with 3 µm and 1 µm diamond suspensions, thoroughly washed with acetone, ethanol and copious amounts of deionized water, dried in a stream of high purity nitrogen and then UV-treated for 10 min [38]. The colloid probe was prepared by attaching the goethite particle (10-30 µm from crushed goethite crystals selected under a microscope using a 3D micromanipulator) to the apex of a micro-fabricated AFM cantilever with an epoxy resin [5,26], as shown in Figure 2.…”

Section: Goethite Substrate Wafer and Colloidal Probementioning

confidence: 99%

“…Goethite (α-FeOOH) is one of the most important mineral fractions in red mud. This mineral can be naturally hydroxylated and wetted by water at all pH values, and, therefore, can produce strong hydration interactions with many other hydrophilic surfaces [3][4][5][6]. The isoelectric point of goethite is pH 6 -pH 9.5 as reported in the literature [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Interaction forces between goethite and polymeric flocculants and their effect on the flocculation of fine goethite particles

Liang

Nguyen

Wen-mi

et al. 2018

Chemical Engineering Journal

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Goethite is a major component in many mineral processing operations. Its presence can have adverse effects on solid/liquid separations. To understand the interactions between goethite surfaces and their influence on particle flocculation, the anionic polymer flocculants ammonium polyacrylate (NHPA), hydrolysed polyacrylamide (PHPA), and hydroxamic polyacrylamide (HXPA) were studied using a combination of atomic force microscopy (AFM), floc structure analyses, and settling tests. The floc settling velocity related to the different flocculants had the following order: NHPA > HXPA > PHPA. The different floc sizes indicated many small and large sized flocs formed with NHPA and PHPA, while monomodal medium sized flocs formed with HXPA. The mass fractal dimension values showed that more compact flocs were formed with HXPA than the other flocculants. The direct force measurements without flocculants confirmed that the goethite surfaces strongly repel each other in alkaline solutions, which agrees with DLVO theory for similarly charged surfaces. The various interactions measured with different flocculants can be related to their molecular structures and molecular weights. The incubation of NHPA at various pH values resulted in long-range adhesion after surface contact with multiple elastic minima, indicating strong adsorption and an expanded molecular conformation for the adsorbed flocculant. The strong elastic minima and long-range adhesion for HXPA indicated a strong adsorption of 2 this hydroxamic flocculant, consistent with the flocculation performance. The force interactions support the results of the settling tests and floc structures well, and AFM could be a good method for studying the relationship between surface interactions and particle flocculation in polymer flocculants.

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The surface state of hematite and its wetting characteristics

Cited by 96 publications

References 45 publications

Surface Properties and Floatability Comparison of Aegirite and Specularite by Density Functional Theory Study and Experiment

Surface Properties and Floatability Comparison of Aegirite and Specularite by Density Functional Theory Study and Experiment

Synthesis of iron oxide films by reactive magnetron sputtering assisted by plasma emission monitoring

Interaction forces between goethite and polymeric flocculants and their effect on the flocculation of fine goethite particles

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