Reduction of the slime contamination on fine coking coal by using the reverse-and-direct flotation process

Zhu, Zhanglei; Yin, Wanzhong; Yang, Bin; Fu, Yanghe; Xue, Jiwei

doi:10.1016/j.colsurfa.2019.123681

Cited by 17 publications

(5 citation statements)

References 28 publications

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“…6,17 Slime coating, which generally happens by electrostatic attraction between oppositely charged mineral particles, 16,18 can reduce the hydrophobicity of the valuable mineral and further hinder the contact with the collector and bubbles, leading to the deterioration in flotation performance. 17,19,20 In addition, because of the characteristic of anisotropic, fine and nonspherical particles with high aspect ratio, clay minerals can cause complex rheological behavior and increase the pulp viscosity. 21−23 Furthermore, it was found that high slurry yield stress could lead to the generation of small bubbles, resulting in low gas hold-ups.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Mechanical entrainment of clay minerals significantly reduces the grade of valuable minerals recovered by flotation . The mechanical entrainment increases with decreasing particle size, and clays with smaller size will be easily transported to the froth and show a negative effect on the grade of concentrate. , Slime coating, which generally happens by electrostatic attraction between oppositely charged mineral particles, , can reduce the hydrophobicity of the valuable mineral and further hinder the contact with the collector and bubbles, leading to the deterioration in flotation performance. ,, In addition, because of the characteristic of anisotropic, fine and nonspherical particles with high aspect ratio, clay minerals can cause complex rheological behavior and increase the pulp viscosity. − Furthermore, it was found that high slurry yield stress could lead to the generation of small bubbles, resulting in low gas hold-ups . Zhang and Peng investigated the effect of clay minerals on pulp viscosity and found that higher pulp viscosity corresponded to lower recovery.…”

Section: Introductionmentioning

confidence: 99%

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Role of Montmorillonite, Kaolinite, or Illite in Pyrite Flotation: Differences in Clay Behavior Based on Their Structures

et al. 2020

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It is widely acknowledged that clay minerals have detrimental effects on the process of flotation, but the mechanisms involved are still not fully understood. In this work, the effects of montmorillonite, kaolinite, and illite on pyrite flotation were investigated from the perspective of various structures of clay minerals. Flotation tests suggested that the detrimental effect of clay minerals on the flotation of pyrite increased as follows: montmorillonite > kaolinite > illite. With the help of rheology measurements, it was found that montmorillonite significantly increased pulp viscosity, which in turn substantially reduced pyrite recovery and grade. Scanning electron microscopy (SEM) images suggested that montmorillonite formed the “house-of-cards” structure by edge-to-edge and edge-to-face contact, while kaolinite and illite platelets were associated mainly in the face-to-face mode. In addition, it was clearly observed by SEM–energy dispersive spectrometry that montmorillonite and kaolinite coat on the pyrite surfaces, which would lower the surface hydrophobicity of pyrite. Kaolinite covered much larger area of pyrite surface than montmorillonite owing to the positive charge occurring at the exposed aluminum–oxygen octahedral sheet of kaolinite. Although illite has a similar 2:1 structure to montmorillonite, it showed little or no effect on pyrite flotation, which was attributed to its poor swelling nature. These findings shed light on the root cause of the adverse effect of clay minerals on pyrite flotation and are expected to provide theoretical guidance for mitigating the negative effects on flotation caused by clays.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Role of Montmorillonite, Kaolinite, or Illite in Pyrite Flotation: Differences in Clay Behavior Based on Their Structures

et al. 2020

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“…It is difficult to effectively recover its fine particle size (<.5 mm) through conventional flotation methods 1,2 . Reverse flotation technology, as a promising low‐order coal slurry upgrading technology, has gradually attracted industry attention in recent years 3,4 . Compared with the extremely complex composition and surface properties of coal, the target minerals such as kaolinite and quartz that act as collectors in the reverse flotation process have relatively stable chemical composition, structure, and surface properties, which is conducive to the targeted design of collectors 5 .…”

Section: Introductionmentioning

confidence: 99%

“…1,2 Reverse flotation technology, as a promising low-order coal slurry upgrading technology, has gradually attracted industry attention in recent years. 3,4 Compared with the extremely complex composition and surface properties of coal, the target minerals such as kaolinite and quartz that act as collectors in the reverse flotation process have relatively stable chemical composition, structure, and surface properties, which is conducive to the targeted design of collectors. 5 However, previous studies have shown that there is mainly a problem of poor collector selectivity in the reverse flotation process of low rank coal.…”

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confidence: 99%

Study on quantitative structure–activity relationship of amine surfactants in coal reverse flotation

Shen,

Li,

Gong

et al. 2023

Asia-Pacific J Chem Eng

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With the deterioration of underground coal quality, hundreds of millions of tons of coal slime in China need to be treated using flotation methods every year. However, the design and selection of coal slurry flotation collectors lack theoretical guidance. In this paper, the quantitative structure–activity relationship (QSAR) model between the molecular structure descriptors of collectors and the flotation recovery and selectivity index is established by using pure kaolinite/clean coal flotation experiments and molecular simulation techniques. Flotation results showed that the flotation recovery rate of kaolinite by collectors with larger head group size, such as DDMAC, DDP, and DTAC, is higher than that of the other collectors with smaller head group size. DDA, DDP, and DD have similar flotation capabilities for clean coal, and their selectivity was slightly better than others. The QSAR model between the molecular structure descriptor and the selectivity index was successfully constructed by combining flotation experiments and molecular simulation results. The reliability of this model has been proven through theoretical analysis and flotation experiments. The molecular simulation results indicate that all eight collectors can advertise on 001 (−) surface of kaolinite, but the final advertisement configuration is different. DDA has less coverage on the surface of kaolinite. When the collector is DDA, the concentration of water molecules near the 001 (−) surface of kaolinite is the highest, indicating that the collector DDA has the weakest effect on improving the hydrophobicity of the 001 (−) surface of kaolinite. DDMAC and DDBAC have the best facilitation to the surface hydrophobicity of kaolinite 001 (−). The research results have theoretical guidance significance for the selection and design of mineral flotation collectors.

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“…High-ash fine slime is mainly composed of fine-grained clay minerals and micro-minerals produced in the process of sliming. A large amount of high-ash fine slime tends to coat the surface of coal particles via electrostatic attraction and reduce surface hydrophobicity, which results in a low recovery rate of combustibles [5,6]. Moreover, due to its light weight and small particle size, the heterogeneous slime is entrained into the clean coal by non-inertial motion, further deteriorating the flotation process [7,8].…”

Section: Introductionmentioning

confidence: 99%

Research on Mechanisms of Improving Flotation Selectivity of Coal Slime by Adding Sodium Polyphosphate

Wang

Zhao

et al. 2022

Minerals

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A high percentage of high-ash fine slime materials can deteriorate flotation selectivity through surface covering. This covering of the surface is one of the issues that need to be addressed for efficient flotation processing of difficult-to-separate and high-ash coals. In this study, we investigated the depression effect of SPP on high-ash fine mud by flotation kinetic tests. We also revealed the mechanism of SPP depression of fine slime flotation and enhanced flotation selectivity of difficult-to-separate and high-ash coals by means of Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and Atomic Force Microscopy (AFM) analyses. The results showed that under the best condition of SPP dosage, clean coal with 9.75% ash content and 76.76% yield was obtained. Compared to the blank group, the ash content of the clean coal decreased by 2.39%, while the yield was only reduced by 2.18% in the presence of SPP. The reason for this was that the addition of SPP enhanced the stripping and dispersion of the gangue from the coal particle surface. The result was a reduction in the cover of the coal grain surface and an increase in the hydrophobic sites on the coal surface, thereby depressing the non-selective flotation of the gangue and enhancing the adsorption of the collector on the coal surface. The ash content of the flotation concentrate decreased, but the yield remained almost unchanged, which was the main reason for the better performance of SPP as a depressant compared to conventional depressants.

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Reduction of the slime contamination on fine coking coal by using the reverse-and-direct flotation process

Cited by 17 publications

References 28 publications

Role of Montmorillonite, Kaolinite, or Illite in Pyrite Flotation: Differences in Clay Behavior Based on Their Structures

Role of Montmorillonite, Kaolinite, or Illite in Pyrite Flotation: Differences in Clay Behavior Based on Their Structures

Study on quantitative structure–activity relationship of amine surfactants in coal reverse flotation

Research on Mechanisms of Improving Flotation Selectivity of Coal Slime by Adding Sodium Polyphosphate

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