Fine-grained pyrite in some Chinese coals

Wang, Wenfeng; Sang, Shuxun; Bian, Zhengfu; Duan, Piaopiao; Qian, Fuchang; Lei, Shaogang; Qin, Yong

doi:10.1177/0144598716646033

Cited by 8 publications

(17 citation statements)

References 53 publications

(84 reference statements)

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“…There are a large amount of fine‐grained clay minerals and pyrite existing in Rongyang coals (Figure ). Wang et al considered that fine‐grained pyrite is generally <10 μm in size. The sizes of these fine‐grained minerals in Rongyang coals are in the range of 1‐10 μm.…”

Section: Resultsmentioning

confidence: 99%

Modes of occurrence and removal of toxic elements from high‐uranium coals of Rongyang Mine by stepped release flotation

Duan

Wang

Sang

et al. 2019

Energy Science & Engineering

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The Rongyang coals from Guizhou, southwestern China, are significantly enriched with uranium (U) and other toxic elements, such as vanadium (V), chromium (Cr), molybdenum (Mo), cobalt (Co), copper (Cu), and selenium (Se). Therefore, it is necessary to remove these toxic elements from high‐U coals before combustion. Previous studies have shown that U cannot be effectively removed by flotation and gravity separation. In this study, the stepped release flotation and acid leaching tests were conducted for coals of the Longtan Formation from the Rongyang Mine. The results from these analyses are as follows: (a) Stepped release analyses revealed that a multistage cleaning process can help to separate toxic elements from cleaned coals; (b) The removal of toxic elements by stepped release and acid leaching is closely related to their mode of occurrence. Vanadium, Cr, Mo, and U were difficult to be removed by stepped release flotation, which due to a significant proportion of them occur in organic matter and fine‐grained minerals; (c) Compared to flotation, most elements were better to be removed by stepped release flotation. In comparison with gravity separation, U had a higher removability by stepped release flotation, while the removal effect of thiophilic element by gravity separation was greater than by flotation; (d) After stepped release flotation, toxic elements Sc, V, Cu, Se, Mo, Hg, and U are still enriched in cleaned coals, suggesting that these elements cannot be fully removed through stepped release flotation.

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Section: Resultsmentioning

confidence: 99%

Modes of occurrence and removal of toxic elements from high‐uranium coals of Rongyang Mine by stepped release flotation

Duan

Wang

Sang

et al. 2019

Energy Science & Engineering

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“…The occurrence and size distribution of pyrite are determined by the depositional environment of coal. − The particle size of pyrite in different occurrence modes varies greatly, ranging from centimeters to submicrons. Coarse-particle pyrite is mainly enriched in agglomerated, nodular, and fracture-filling forms, and fine-grained pyrite has a relatively complex occurrence state, including framboïdal, euhedral crystalline, spherical, caviar-like, fine-grained agglomerated, etc. − Flotation is a common desulfurization method of coal before combustion, which has the advantages of cost savings and environmental protection. Generally, pyrite with coarse particles larger than 60 μm in diameter can be removed by conventional flotation methods. , …”

Section: Introductionmentioning

confidence: 99%

“…However, fine-grained pyrites (smaller than 60 μm) are difficult to separate by the flotation method. − On the one hand, the formed foam of the mixture of fine-grained pyrite and coal particles during the flotation process has strong stability and low fluidity, making the pyrite difficult to separate from coal . On the other hand, the fine-grained pyrite can form a complex symbiotic relationship with the coal matrix, , resulting in a flotation behavior similar to that of coal particles. In addition, the sulfur atoms on the crystal surface of fine-grained pyrite are easily replaced by carbon atoms, ,, reducing the physical adsorption ability of pyrite toward water molecules and increasing the difficulty of separation.…”

Section: Introductionmentioning

confidence: 99%

“…Generally, a grinding particle size distortion smaller than 20 μm can gradually affect the flotation recovery, and the smallest pyrite particle size with desulfurization effect in conventional flotation experiments is about 10 μm. , Zhang et al suggested that 10–120 μm is the optimal particle size for the separation of pyrite in a flotation experiment . Besides, scholars have carried out much research on the growth mechanism, ,, crystal structure, and occurrence state ,, of pyrite crystals. However, there are few reports regarding the occurrence and morphology of fine-grained pyrite in coal and the comprehensive effects of fine-grained pyrite size and occurrence state on flotation desulfurization.…”

Section: Introductionmentioning

confidence: 99%

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Occurrence Characteristics of Fine-Grained Pyrite in Coal and Its Scaling Effect on Flotation Desulfurization

Wang

Zhang

2022

ACS Omega

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To explore the occurrence and distribution characteristics of fine-grained pyrites in coal and the effect of pyrite particle size on flotation efficiency, coal samples from Guizhou province and Shanxi province, China, were selected for pyrite morphology observation and sulfur content test before and after flotation desulfurization experiments with different coal particle sizes. Experimental results showed that the fine-grained fine pyrites in coal have various occurrence forms and complex connections with the coal matrix. The fragmentation process can change the distribution of pyrite content in coal. Flotation desulfurization experiments showed that the sum of pyrite content in the cleaned coal and middlings gradually became significantly higher in coal particles with size 15–37 μm compared with particle sizes 37–44 and 44–75 μm. The complex occurrence morphology and crystal structure of fine-grained pyrite make it difficult to be removed from the coal matrix by ore grinding during flotation. Fine-grained pyrite mainly occurs in the form of framboïdal pyrite, disseminated pyrite, and monomer pyrite with a size of 0.69–33.94 μm in the middlings and cleaned coal. Therefore, 37 μm is considered as the critical dimension for ore grinding to improve the effective flotation desulphurization efficiency in this study, and some more effective methods should be used to increase the desulfurization efficiency of fine-grained pyrite.

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“…CGPCA is rich in hazardous minerals, such as pyrite. Pyrite is a very dense mineral, mainly found in the form of microcrystalline particles embedded in CGPCA, 2 and its shape is irregular, difficult to grind, and a source of sulfur dioxide (SO 2 ). This mineral circulates in the mill many times, resulting in an increased mill cycle ratio (the ratio of the separator feed to the qualified coal powder).…”

Section: Introductionmentioning

confidence: 99%

Study of the Fluidized Separation Process of Irregular Coarse-Grained Pulverized Coal Agglomerates Based on Modified Computational Fluid Dynamics─Population Balance Method

Zheng

et al. 2022

ACS Omega

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In this work, the agglomeration, fragmentation, and separation process of coarse-grained pulverized coal agglomerates (CGPCA) obtained from a power plant were achieved using gas–solid fluidized bed sorting and analyzed through a combination of numerical simulations and actual experiments with CGPCA. To study the polydispersity and irregularity of CGPCA, the CGPCA surface fractal dimension was calculated using fractal dimension combined with scanning electron microscopy. The two-section fractal dimension of the particle size distribution was obtained by fitting the logarithmic particle size distribution of CGPCA. On the basis of the obtained data, the polydisperse particle drag force model, the agglomeration kernel function, and the breakage kernel function were modified. Thus, an irregular polydisperse gas–solid two-phase Eulerian–Eulerian model was constructed to simulate the sorting process of CGPCA in the fluidized bed. The results of the numerical simulation investigation were compared with the experimental results and showed that the simulation data, which considered the two section fractal dimension, was in better agreement with the experimental results. The cumulative logarithmic distribution of CGPCA’s size was segmented and fitted. The values of the two section fractals of the agglomerates were determined as D = 1.014 and D = 2.401, respectively. Analysis revealed that the optimal separation efficiency working condition in the simulation process, providing the highest separation efficiency of 54.7%, was generated at air velocity of 1.21 m/s.

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Fine-grained pyrite in some Chinese coals

Cited by 8 publications

References 53 publications

Modes of occurrence and removal of toxic elements from high‐uranium coals of Rongyang Mine by stepped release flotation

Modes of occurrence and removal of toxic elements from high‐uranium coals of Rongyang Mine by stepped release flotation

Occurrence Characteristics of Fine-Grained Pyrite in Coal and Its Scaling Effect on Flotation Desulfurization

Study of the Fluidized Separation Process of Irregular Coarse-Grained Pulverized Coal Agglomerates Based on Modified Computational Fluid Dynamics─Population Balance Method

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