Removal of Mercury from Fine Coal Based on Combined Coal Processing Approaches

Liu, Cheng; Zhou, Changchun; Cong, Long-Fei; Pan, Jinhe; Tang, Mengcheng; Cao, Shan Shan

doi:10.1021/acs.energyfuels.7b02133

Cited by 6 publications

(4 citation statements)

References 42 publications

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“…12 Previous studies mainly focused attention on the air pollution of Se caused during coal combustion, the content and distribution, modes of occurrence of Se in coal from the aspect of geology, or the removal of it from coal by conventional coal cleaning approaches. 13 However, the potential impact of Se release from coal into water are often ignored. The problem should be taken into consideration in the wet coal preparation process, as coal is completely soaked in water during this process.…”

Section: Introductionmentioning

confidence: 99%

Release Behavior of Se from Coal into Aqueous Solution

2018

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The release of harmful trace elements from solid such as coal into the water is closely related to human health. The aim of this paper is to study the release procedure of selenium (Se) from coal in aqueous solution. Effects of contact time, pH, and temperature were investigated via a set of batch release tests. Experimental results were also analyzed from the aspects of dynamics and thermodynamics. Batch release tests showed that the release capacity of Se increasees with the increase of contact time and temperature, and it is higher in strong acid or alkaline conditions than in neutral conditions. Dynamic fitting analyses indicated that the release model of Se from coal into water is different with different pH values, and the applicability of different models suggested that the release mechanism of Se is multiple. The first-order kinetics fitting demonstrated that the release procedures of Se from coal into the water with the initial solution pH of 3 and 11 are two-stage release processes. And the best fitting of a pseudo-second-order model manifested the process is mainly controlled by chemical reaction. Thermodynamics analyses indicated that the release of Se from coal into water is an endothermic reaction, and the release enthalpy of Se is 18.314 and 3.533 kJ/mol at the solution pH 7 and 11, respectively.

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Section: Introductionmentioning

confidence: 99%

Release Behavior of Se from Coal into Aqueous Solution

2018

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“…Duan et al studied the removal of toxic elements via the flotation of high-sulfur coal in Southwestern China and found that flotation was an effective way to remove toxic elements from coal . Liu et al found that Hg was obviously removed from fine coal by combined flotation and gravity separation approaches . Zhou et al found that the removal rate of arsenic in coal by flotation was higher than that by gravity separation .…”

Section: Introductionmentioning

confidence: 99%

“…20 Liu et al found that Hg was obviously removed from fine coal by combined flotation and gravity separation approaches. 24 Zhou et al found that the removal rate of arsenic in coal by flotation was higher than that by gravity separation. 22 Different from the high-rank coal, the low-rank coal contains more hydroxyl, carboxyl, and carbonyl hydrophilic groups, which accounts for its high porosity and poor floatability.…”

Section: ■ Introductionmentioning

confidence: 99%

Distribution and Migration of Trace Elements during Flotation in Ge-Rich Low-Rank Coal from Wulantuga Coal Mine, Inner Mongolia, China

et al. 2022

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The high-Ge low-rank coal in Wulantuga Coal Mine, Inner Mongolia, China, has a high utilization value due to its enrichment of critical element Ge. However, it is also enriched with toxic elements such as Be, F, As, and Hg; therefore, the coal should be cleaned before use. In this study, the flotation experiment, X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FTIR) analysis, and the release experiment for the high-Ge low-rank coal from Wulantuga were carried out, and the results are as follows. (1) The total mineral content of the feed coal is higher than that of the cleaned coal and tailing, and the content of the functional group −OH is also increased, indicating that the moisture in the cleaned coal is increased after flotation. (2) Argillation occurred and some minerals (dihydrate gypsum and kaolinite) and elements were released into the water during flotation, so the ash yield and the percentage of TiO2, Al2O3, Fe2O3, MgO, and CaO of the cleaned coal and tailing are lower than those of feed coal. (3) The concentrations of elements Li, Be, F, Mn, Zn, Sr, Hg, Tl, and Pb of the cleaned coal are higher than those of tailing, indicating that these elements are more likely to occur in organic matter or fine-grained mineral embedded in organics, but the concentration of other elements such as Ge, As, Sb, and W in the cleaned coal is lower than that of tailing, suggesting that these elements are weakly associated with organics or occur in minerals. (4) After flotation, trace elements Be, Cs, Ti, Ge, Sb, and W enriched in the feed coal were removed in large quantities, while F, As, and Hg were difficult to remove; therefore, other preparation methods should be tried. (5) The release experiment showed that the release rate of chalcophile and siderophile elements and rare earth elements and yttrium (REY) is relatively higher. In addition to those of Be, Ga, Sr, and Cs, the release rate of most elements is relatively low.

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“…Uranium is a naturally radioactive element, and the ultrafine particles released from U‐rich coals during combustion can have potentially adverse effects on human health . Coal preparation is one effective approach to reducing environmental pollution from toxic elements . At present, the most widely applied method of removing toxic elements from coal is gravity separation .…”

Section: Introductionmentioning

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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Removal of Mercury from Fine Coal Based on Combined Coal Processing Approaches

Cited by 6 publications

References 42 publications

Release Behavior of Se from Coal into Aqueous Solution

Release Behavior of Se from Coal into Aqueous Solution

Distribution and Migration of Trace Elements during Flotation in Ge-Rich Low-Rank Coal from Wulantuga Coal Mine, Inner Mongolia, China

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

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