Understanding and improving the flotation of coals with different degrees of surface oxidation

Chang, Ziyong; Chen, Xumeng; Peng, Yongjun

doi:10.1016/j.powtec.2017.08.025

Cited by 40 publications

(21 citation statements)

References 27 publications

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“…Processes 2019, 7, x FOR PEER REVIEW 8 of 10 that the floatability, hydrophobicity, and separation efficiency of hydrophilic coal changed dramatically. Chang [12] reported that coal flotation performance decreased with an increase in the degree of surface oxidation, which is consistent with our results.…”

Section: Effect Of Heating Oxidation At 200 °C On the Floatability Ofsupporting

confidence: 92%

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Effect of Heating Oxidation on the Surface/Interface Properties and Floatability of Anthracite Coal

Rong

Wang

et al. 2019

Processes

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Oxidation processes of coal surfaces are both fundamental and interesting from academic and engineering points of view. In this work, we comprehensively analyzed the mechanism of heating oxidation at 200 • C on the surface/interface characters and the floatability of anthracite coal. The variations of surface/interface characters were studied using SEM (scanning electron microscopy), FTIR (Fourier transform infrared spectroscopy), and XPS (X-ray photoelectron spectroscopy). The floatability was further identified using Induction Time and Bubble-Particle Wrap Angle. It was found that, after heating oxidation at 200 • C, both surface ravines and oxygen-containing groups were increased. The degradation of hydroxyl on anthracite could be neglected during the heating, while the oxidation of hydrocarbon chains dominated the balance of hydrophobicity and hydrophilicity on coal surface. The induction time significantly increased from 200 ms to 1200 ms and 2000 ms after 10 h and 20 h of heating oxidation at 200 • C, respectively. Additionally, raw coal exhibited the fastest kinetics of bubble-particle attachment and the largest wrap angle, directly proving that the floatability decreased after oxidation.

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Section: Effect Of Heating Oxidation At 200 °C On the Floatability Ofsupporting

confidence: 92%

“…However, the adsorption efficiency of oil collectors on oxidized coal surfaces was decreased significantly. To float oxidized coals, a number of works on polar collector, pretreatment, and new flotation procedures have been reported [6,[12][13][14][15][16]].…”

Section: Introductionmentioning

confidence: 99%

Effect of Heating Oxidation on the Surface/Interface Properties and Floatability of Anthracite Coal

Rong

Wang

et al. 2019

Processes

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“…As know from the literature, the surface chemical properties, such as element composition [15,16], charge [17], and functional group [18], have an important influence on the wettability of minerals.…”

Section: Introductionmentioning

confidence: 99%

Insight into the Influence of Surface Roughness on the Wettability of Apatite and Dolomite

Wang

Zhang

2020

Minerals

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Surface roughness has an important influence on the wettability of particles. This paper is an innovative exploration to control the surface wettability of apatite and dolomite from the perspective of roughness in the background of phosphate flotation. Roughness characteristics of apatite and dolomite particles and its effects on wettability were investigated with surface roughness, contact angle measurements, and SEM analysis. The relationship between surface energy and wettability of different roughness surfaces was also discussed. The results indicated that the influence of roughness on apatite and dolomite particles showed the same regularity, and wettability increased with the increasing roughness for hydrophilic surfaces, while the wettability decreased for hydrophobic surfaces. The influence of roughness on wettability can be well explained by Wenzel and Cassie models, and the surface energy of different rough surfaces had a strong correlation with their wettability. When sodium oleate was added after acid treatment, the apatite was hydrophilic, while the dolomite was hydrophobic; the difference in wettability between them became greater as surface roughness increased. Thus, it can be predicted that the selective separation of dolomite and apatite under acid reverse flotation conditions can be strengthened by increasing the mineral surface roughness during comminution.

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“…Hydrogen bonding between the oxidized coal surface and the polar collector was considered to be the mechanism of flotation intensification. Chang et al [7] also found that a mixture of diesel and Triton X-100 was beneficial to the oxidized coal flotation process. The polar Triton X-100 collector concentration required to achieve a satisfactory recovery was found to be proportional to the degree of coal oxidation.…”

Section: Introductionmentioning

confidence: 98%

Effect of Dodecane and Oleic Acid on the Attachment between Oxidized Coal and Bubbles

Xing

Cao

et al. 2018

Minerals

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Abstract:The objective of this study is to explain the different flotation responses observed in oxidized coal flotation when using a nonpolar flotation collector, dodecane, versus a polar flotation collector, oleic acid. Particularly, the effect of each flotation collector on bubble-coal particle attachment was investigated. Colloidal probe atomic force microscopy (AFM) was used to directly measure the force between a model coal surface and a model bubble in the presence of either dodecane or oleic acid. Pyrolytic graphite (PG) treated with oxygen plasma and a polymethylmethacrylate (PMMA) particle were selected to represent the model oxidized coal surface and model bubble. High speed visualization for bubble-oxidized coal attachment was used to monitor the attachment behavior between bubble and oxidized coal in presence of dodecane and oleic acid, respectively. It was found that the force between the oxidized PG and the PMMA particle in Milli-Q water was monotonically repulsive, illustrating that oxidized coal particles attach onto bubble surface with difficulty. The flotation recovery using a traditional hydrocarbon oil, dodecane, was always lower than when oleic acid was used at a low dosage (300-1100 g/t). The force measurements showed that an attractive hydrophobic force was introduced when a 0.01 mM oleic acid solution was used, while the force was still repulsive in presence of a 0.01 mM dodecane solution. The minimum contact time for successful attachment between oxidized coal surface and bubbles in the presence of 0.01 mM oleic acid is much shorter than that in 0.01 mM dodecane. However, a high flotation recovery of 85.81% was obtained when dodecane concentration was further increased to 1700 g/t. The significant jump into contact effect observed in the AFM force curves and the short induction time in the presence of 1 mM dodecane solution was responsible for this high flotation recovery.

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Understanding and improving the flotation of coals with different degrees of surface oxidation

Cited by 40 publications

References 27 publications

Effect of Heating Oxidation on the Surface/Interface Properties and Floatability of Anthracite Coal

Effect of Heating Oxidation on the Surface/Interface Properties and Floatability of Anthracite Coal

Insight into the Influence of Surface Roughness on the Wettability of Apatite and Dolomite

Effect of Dodecane and Oleic Acid on the Attachment between Oxidized Coal and Bubbles

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