Estimated radioactivity of solid fossil fuels

Shpirt, M. Ya.; Пунанова, С. А.

doi:10.3103/s0361521914010091

Cited by 7 publications

(10 citation statements)

References 4 publications

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“…Complex Ca, Mg, and Fe-humates contain up to 40% of calcium of the mineral component. 45 Initial Tugnuysky coal contains low sulfur (0.2−0.7%) and low phosphorus (0.03%) and include finely dispersed disseminated syngenetic minerals: marcasite and pyrite (FeS 2 ), siderite (FeCO 3 ), and chalcopyrite (CuFeS 2 ). Epigenetic inclusions, such as calcite, chalcedony, pyrite, siderite, iron oxide, and ferric and ferrous, compounds form films and pseudomorphs on mineral and organic remains.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…47 In the initial lignite, the silicate component includes not only quartz, kaolinite, illite, and montmorillonite but also feldspars that account for up to 40 wt % of the mineral component of coals. 45 Among the listed silicate forms, the SiO 2 /Al 2 O 3 ratio is 1.18 for one of the extreme members in the series of Na, Cafeldspars (anorthite: CaAl 2 Si 2 O 8 ), 58 which coincides with the coefficient value in eq 3c in and is close to coefficient values of 1.19 and 1.17 in eqs 1c and 2c for the dependence SiO 2 = f(Al 2 O 3 ) (Figure 6). Therefore, it may be concluded that anorthite is involved in the formation of blocklike FSs of both series as an aluminosilicate precursor.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Composition, Structure, and Formation Routes of Blocklike Ferrospheres Separated from Coal and Lignite Fly Ashes

et al. 2020

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The structure–composition relationship of blocklike ferrospheres (FSs) isolated from fly ash from the coal and lignite combustion has been studied systematically by scanning electron microscopy and energy dispersive X-ray spectroscopy. Groups of globules for which the gross composition of polished sections corresponds to the general equations for the relationship of the concentrations SiO2 = f(Al2O3) and CaO = f(SiO2) are highlighted from FSs of two series. It is shown that blocklike FSs are formed during the sequential transformation of dispersed products of thermal conversion of mineral precursor associates: pyrite, quartz, and Ca, Al-humates in the case of brown coal; and pyrite, siderite, quartz, and calcite in the case of coal. Anorthite is the aluminosilicate precursor of blocklike FSs of both series. The dependence CaO = f(SiO2) that reflects the influence of glass-forming components reveals six groups of FSs. An analysis of SEM images of polished globule sections demonstrates that an increase in the concentration of glass-forming components in all groups is accompanied by gradual changes in the structure of globules, from a large blocklike type to a fine crystalline type with a high glass-phase content. The size and shape of crystallites are controlled by the size of a local melt area where the total concentration of spinel-forming oxides exceeds 85 wt %. An increase in the glass-phase concentration and a decrease in the crystallite size in globules with FeO ≤ 46–50 wt % are explained by expansion of the segregation region in the FeO–Fe2O3–SiO2 system as the oxidation potential rises.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Composition, Structure, and Formation Routes of Blocklike Ferrospheres Separated from Coal and Lignite Fly Ashes

et al. 2020

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“…Pyrite impurity is distributed over the organic matter of coal as disseminated grains, single crystals sized 0.001−0.5 mm, and spherical structures 0.02−2 mm in diameter. 3,49 The thermochemical transformation of the mineral precursors of both coals leads to the formation of blocklike globules, whose major component composition corresponds to the general equations of the relationship. The nature of the ironcontaining precursor is reflected in the composition of ferrospinel crystallites and the globule structure.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Composition–Structure Relationship and Routes of Formation of Blocklike Ferrospheres Produced by Pulverized Combustion of Two Coal Types

2021

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The composition−structure relationship of blocklike ferrospheres (FSs) isolated from fly ash produced during the combustion of two different types of coal was studied systematically by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. Monoblock globules were shown to consist of large sintered crystallites of Mg, Mn ferrospinel, which are formed from excluded siderite particles containing isomorphic impurities of magnesium and manganese carbonates. The common groups of globules for which the gross composition of polished sections corresponds to the general equations for the relationship of the concentrations SiO 2 = f(Al 2 O 3 ) and CaO = f(SiO 2 ) were highlighted from FSs of two series. These globules are formed during the thermochemical transformation of associates of siderite, quartz, calcite, and anorthite, which have a silicate modulus of SiO 2 /Al 2 O 3 equal to 1.18, which corresponds to the coefficients in the general equations of the relationship SiO 2 = f(Al 2 O 3 ). SEM analysis of polished cross-sections of the globules of selected FS groups demonstrates that the crystallite size of ferrospinel decreases, while the content of the glass phase increases with the declining FeO concentration in individual globules. The crystallite size and shape are found to depend on the size of the local melt area where the concentration of spinel-forming oxides is >85 wt %. The observed increase in the glass-phase content is attributed to the broadening of the liquation zone in the FeO−Fe 2 O 3 −SiO 2 system as the oxidative potential increases and to the higher content of [Fe 3+ O 2 ] − and [Fe 3+2 O 5 ] 4− ferrite complexes in calcium-rich melts.

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“…Kaolinite clay minerals in combination with quartz are the predominant mineral components of hard coal from the Ekibastuz deposit; hydromicas, feldspars, siderite, pyrite, calcite, dolomite, gypsum, and magnesite are also present. 36,43−45 Individual carbonaceous rocks include nonstoichiometric mixtures and contain montmorillonite, 44 which can be associated with kaolinite, quartz, or illite/montmorillonite mixed-layer minerals, 43 as well as be present within hydromicas (illlite/smectite minerals with a low smectite content). 46 The conditions of groundwater recharge and accumulation in the Ekibastuz coal basin are responsible for the stagnant nature and high mineralization of groundwater; 36 the cationic exchange in clay minerals gives rise to mixed-layer phases with diverse compositions.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Scanning Electron Microscopy–Energy-Dispersive X-ray Spectrometry (SEM–EDS) Analysis of PM_1–2 Microspheres Located in Coal Char Particles with Different Morphologies

et al. 2020

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Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to analyze individual microspheres, 1−2 μm in size, located in coal char particles of Inertoid and Fusinoid/Solid morphological types. It was shown that PM 1−2 (where PM = inorganic particulate matter) is formed in the porous structure of the carbon matrix, which controls the microsphere size, from authigenic minerals that determine their composition. Depending on the contents of SiO 2 , Al 2 O 3 , and FeO, the studied microspheres fall into various groups differing in mineral precursors. The precursor of the Group 1 microspheres with the specific composition of SiO 2 + Al 2 O 3 > 95 wt % and FeO ≤ 1.5 wt % is NH 4 −illite. Microspheres containing SiO 2 + Al 2 O 3 < 95 wt % and FeO in increasing content amounts up to 4, 6, and 10 wt %, included in Group 2, Group 3, and Group 4, respectively, are formed from mixed-layer K−illite−montmorillonite minerals subjected to cationic substitution with iron, followed by the entry of Fe 3+ in interlayer sites. Calcite, dolomite, gypsum, magnesite, rutile, and siderite are involved in the formation of Group 5 microspheres with a high content of Ca, Mg, Ti, or Fe. The significant part of PM 1−2 is represented by microspheres of Groups 2, 3, and 4 regardless of the type of coal char particles (62% for Inertoid ones and 75% for Fusinoid/Solid ones). About one-third of the microspheres for both char morphotypes refer to Group 5. Microspheres of Group 1 (8%) are located only in the Inertoid char particles, which results from the characteristic effect of the maceral−mineral composition of original coal. It has been suggested that Inertoid and Fusinoid/Solid char particles are formed from various macerals, semifusinite and fusinite, respectively. Due to the closed-cell structure, semifusinite contains noncation-exchanged NH 4 −illite, the mineral precursor of microspheres with low contents of Fe, K, Na, and Mg. The fusinite structure allows cationic substitution in NH 4 −illite with the formation of mixed-layer K−illite and montmorillonite, the mineral precursors of a significant part of PM 1−2 .

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Estimated radioactivity of solid fossil fuels

Cited by 7 publications

References 4 publications

Composition, Structure, and Formation Routes of Blocklike Ferrospheres Separated from Coal and Lignite Fly Ashes

Composition, Structure, and Formation Routes of Blocklike Ferrospheres Separated from Coal and Lignite Fly Ashes

Composition–Structure Relationship and Routes of Formation of Blocklike Ferrospheres Produced by Pulverized Combustion of Two Coal Types

Scanning Electron Microscopy–Energy-Dispersive X-ray Spectrometry (SEM–EDS) Analysis of PM_1–2 Microspheres Located in Coal Char Particles with Different Morphologies

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Estimated radioactivity of solid fossil fuels

Cited by 7 publications

References 4 publications

Composition, Structure, and Formation Routes of Blocklike Ferrospheres Separated from Coal and Lignite Fly Ashes

Composition, Structure, and Formation Routes of Blocklike Ferrospheres Separated from Coal and Lignite Fly Ashes

Composition–Structure Relationship and Routes of Formation of Blocklike Ferrospheres Produced by Pulverized Combustion of Two Coal Types

Scanning Electron Microscopy–Energy-Dispersive X-ray Spectrometry (SEM–EDS) Analysis of PM1–2 Microspheres Located in Coal Char Particles with Different Morphologies

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Product

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Scanning Electron Microscopy–Energy-Dispersive X-ray Spectrometry (SEM–EDS) Analysis of PM_1–2 Microspheres Located in Coal Char Particles with Different Morphologies