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Geochemistry and nano-mineralogy of feed coals and their coal combustion residues from two different coal-based industries in Northeast India Shahadev Rabha, Jyotilima Saikia, K.S.V. Subramanyam, James C. Hower, Madison M. Hood, Puja Khare, and Binoy K Saikia Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b03907 • Publication Date (Web): 09 Feb 2018 Downloaded from http://pubs.acs.org on February 11, 2018

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Nanominerals with hazardous elements in industrial coals 266x89mm (96 x 96 DPI)

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Geochemistry and nano-mineralogy of feed coals and their coal combustion residues from two different coal-based industries in Northeast India Shahadev Rabhaab, Jyotilima Saikiaab, K.S.V. Subramanyamc, James C Howerd, Madison M. Hoodd, Puja Kharee, Binoy K Saikia*ab a

Polymer Petroleum and Coal Chemistry Group, Materials Science & Technology Division, CSIR-

North East Institute of Science & Technology, Jorhat-785006, India b

Academy of Scientific & Inovative Research, CSIR-NEIST Campus, Jorhat-785006, India

c

Geochemistry Division, CSIR- National Geophysical Research Institute, Uppal Road, Hyderabad-

500007 India d

University of Kentucky, Center for Applied Energy Research, 2540 Research Park Drive,

Lexington, KY 40511 e

Agrotechnology Division, CSIR- Central Institute of Medicinal and Aromatic Plants, Lucknow-

226015

Abstract The mineralogy, as well as the geochemistry of feed coals, are very important parameters for understanding the process conditions in a thermal plant. The present paper describes the nanomineralogical and geochemical aspects of a few feed coals and associated coal fly ashes collected from tea processing and brick-making industries from Northeast India. The optical microscopy, Xray diffraction (LTA-XRD), field emission scanning electron microscopy-energy dispersive spectroscopy (FESEM-EDS), and chemical analysis techniques were applied to determine this mineralogical and geochemical aspect. Inductively coupled-mass spectroscopy (ICP-MS) was used to explore the occurrence and distribution of trace and rare earth elements (REEs), which are economically important, and are reported in this paper. The major minerals such as kaolinite, pyrite, quartz, calcite were found to be present in the feed coals with variations with respect to the type of feed samples. The FESEM-EDS analysis revealed the occurance of nanosphere consisiting of AlSi-Fe-S and Al-Si-Mg-As compounds. The potentially hazardous elements (PHEs) including Hg, As, Pd, Cd, Sn, Ni, and Co were also found in one fly ash samples. The REE abundances are observed to be considerably low in comparision to world average coal. A preliminary statistical analysis of the trace and rare earth elements in the coals is performed to understand their mutual correlations.

Keywords: Coal geochemistry; Nano-mineralogy; Coal-based industries; Fly ash; Northeast India *Corresponding author: [email protected]; [email protected]


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1. Introduction Coal is the most abundant, economically, and widely used fossil fuel and energy source in the world. Worldwide consumption of coal during the year 2016 was 3732 million tonnes of oil equivalents (Mtoe) with a growth rate of 1.9% per annum1. Currently, coal provides 41% of global electricity generation, 70% of steel, and 90% of world’s cement production. The worldwide estimated proven coal reserve is about 1.1 trillion tonnes which is enough to last around 150 years at the current rate of production2. India has about 10% of the world’s total coal reserves, enough to last for next 200 years at the current rate of production3. But, unfortunately, the utilization of coal for human benefit causes serious environmental pollution. It is well known that every step of coal utilization processes from mining to combustion emits environmental pollutants. Coal combustion produces airborne pollutants such as carbon dioxide, particulate matter, sulphur dioxide, oxides of nitrogen, acid gases (HCl, HF), and hydrocarbons (PAHs). Emission of pollutants from combustion activities depends on various factors such as presence of toxic elements, sulphur contents, mineral matter (ash yield) of coal burned, combustion condition, and controlling technology4. Coals that appear to be suitable and desirable through proximate and ultimate analysis may have abnormal combustion properties such as unburned carbon present in fly ash yield. Such abnormalities lie not only in the presence or absence of particular maceral groups but also in the way in which the macerals are in the diverse microlithotypes5. Petrographic analysis can provide useful information about the combustion of pulverized coal such as combustion reactivity, pyrolysis, ignition and char burnout which not only depend on the rank or maturity, but also on the composition, distribution and combination of the macerals of coal. It has been suggested that >5 wt % carbon in ash is economically not suitable and there is a risk of industrial combustion problems6. Petrographic analysis of high-sulphur northeast Indian coal shows the high percentage of vitrinite macerals, around 93% of the organic components on a mineral-free basis4. Among the vitrinite component, telovitrinite was the most abundant, followed by other vitrinite-group macerals7. The maximum reflectance and mean random reflectance of vitrinite is 0.6% and 0.58% respectively, indicating a rank of high volatile C bituminous (medium rank D) coal8. ACS Paragon Plus Environment

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Geochemical and mineralogical studies reveal that coal contains large amounts of incombustible mineral matter components which generally form residue or ash during combustion911

. The behaviour of these minerals affects the coal quality, economic value, and the environment.

Due to presence of the high sulphur especially organic sulphur, the northeastern region (NER) coal of India is regarded as low-quality coal12. Our present study deals with the North Eastern Region (NER) Indian coal. The NER coal deserves special attention in view of its cleaner utilization due to the presence of unusual physicochemical properties featuring high organic sulphur content. These coals generally contain 2–8% total sulphur of which 75–90% is of organic sulphur and the rest are in inorganic form viz. sulphate and pyritic sulphur13. The presence of high sulphur in these coals causes acid mine drainage (AMD) around the coalfield14. Clay minerals (such as kaolinite, illite, and mixed-layer illite/smectite) hold trace elements such as Sr, Hf, Li, V, Ga, Rb, Ba, Nb, Cs, U, Th, Zr, Pb, Cd, Mo, Cu, Tl, Sn, Sb, and Zn as these elements have a strong affinity towards pyrite15,16. Further, nano-mineralogical studies using modern analytical techniques such as FE-SEM, HR-TEM/EDS, XRD, ICP-MS, etc. reveal that minerals are not only present in bulk in coal but also in nanoscale level/sizes, which may different physico-chemical properties at their sizes4,7,8,17. It has also been observed that a number of potentially hazardous elements (PHEs) such as As, Cd, Cr, Hg, Pb, Zn, V, etc. remain associated with these nanominerals. Saikia et al.4 found that hematite, magnetite, and goethite adsorb significant concentration of As, Cd, Cr, Hg, Pb, and V in their structures. These nano-minerals have great environmental significance as they get released as ultrafine or nanoparticles with coal fly ash (CFA) and transported by the flue gas into the atmosphere. Studies on CFA reveal that these nanoparticles are associated with PHEs such as As, Cd, Hg, V, Ni, Mo, and Pb4,7. Although lots of research has been conducted on coal for its quality improvement, clean utilization and pollution reduction throughout the world, effective reduction of pollutants has not been made achievable so far because of its diverse chemical composition of minerals in coals, which also varies with the type of coal. Investigation on the petrography, mineralogy and ACS Paragon Plus Environment

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geochemistry of the feed coals and combustion residues at nano-scale levels can facilitate understanding of envisaging pollution and reduce human health impact. Therefore, the objective of the present study is the characterization of minerals in the coal which will help in further research for quality enhancement and pollution reduction.

2. Methods and materials 2.1 Collection of samples In the present study, a total of eight samples were collected for analysis : two raw coal samples (TRP, TRP-NECF) from Tirap coalfield (Assam, Northeast India); four feed-coal samples from two coal-fired industries of Assam, the Brick-making industry (MBF-1, MBF-2) and Teaprocessing industry (HCH, LHP); and one representative fly ash sample (CFA-1, CFA-2) from each industry. However, it is understood that blended coals were being used in the combustion system during sampling. The coal, as well as the coal fly ashes, were air dried, ground to 0.221 mm top size, and kept for further characterization. 2.2 Physico-chemical characterization The coal and fly ash samples were characterized in the CSIR-NEIST Laboratory (India) to determine their physicochemical properties. Proximate analysis of the coal samples were performed using a thermogravimetric analyser (Model: TGA 701; Leco Corporation, USA) according to ASTM standard method18-20. The carbon, hydrogen, and nitrogen contents were determined using a Perkin-Elmer 2400 Elemental Analyser, and total sulfur by a ‘Sulfur Analyser’ (Model: S-144DR; Leco Corporation, USA), following standard methods21,22. The forms of sulfur in the coal samples (pyritic and sulfate sulfur) were determined following the ASTM standard method23 and the percentages of organic sulfur calculated by the difference from total sulfur. 2.3 Petrological characterization Samples of each coals and fly ash were prepared as epoxy-bound particulate pellets, finished with a final 0.05-µm-alumina polish. The samples were examined by reflected light microscopy with a Leitz Orthoplan microscope, using a 50-x reflected-light oil-immersion objective, to provide ACS Paragon Plus Environment

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petrographic information on the samples, especially the organic matter. Vitrinite maximum reflectance was determined using a 9-µm diameter measuring spot, a 546-nm filter, and a Hamatsu photomultiplier following calibration with glass standards. The analysis were carried out at Center for Applied Energy Research, University of Kentucky. 2.4 ICP-MS analysis in coals ICPMS analysis in coals and CFA Samples were applied following procedures as reported elsewhere24,25. Sample solutions were analyzed at CSIR-NGRI, Hyderabad, by high resolution inductively coupled mass spectrometer (HR-ICP-MS) (Nu Instruments Attom, UK) in jumpwiggle mode which permits the analytes of interest to be measured accurately. 2.5 XRD analysis XRD analysis was performed with an X-ray Diffractometer (Rigako, ULTIMA IV). X-ray diffraction data of the samples were obtained with the start angle 5.00, stop angle 100.00, and steep angle 0.02° with a scanning rate of 4° per minute and target CuKα (λ=1.54056 Å). The program

XG operation ‘RINT200’ associated with the XRD was used to process the diffractogram. 2.6 FESEM-EDS analysis of Coals and CFA Field emission scanning electron microscopy (FESEM) images were obtained from a Carl Zeiss Sigma FESEM instrument. Energy dispersive X-ray spectroscopy (EDS) pattern and elemental mapping analysis was recorded on Oxford X Max 20 equipment.

3. Results and discussion 3.1 Physico-chemical characteristics Physico-chemical properties of feed coals play important role in the emission of pollutants during combustion. Table 1 shows the physico-chemical properties of the feed coal samples collected from two industrial sites. The coal samples show the typical characteristics of NER coal with high volatile matter and high sulphur content. The present samples contain 2.80-6.86% total sulphur, where 50-94.02% is of organic sulphur, and rest are in inorganic form such as sulphate and pyritic sulphur. Researchers consider that sulphur were accumulated by the sea water at the early ACS Paragon Plus Environment

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stage of coal formation while iron by the fresh water, which combine to yield ferric sulphate and the resultant product is pyrite12. Organic sulphur in NER coals may occur in different forms such as mercaptan, sulphide, disulphide, thiol or ring compounds which make ts removal very difficult12,13. 3.2 Petrology of the samples 3.2.1 Coal petrology Coals TRP, TRP-NECF, MBF-2, and HCH are clearly blends of high volatile bituminous and subbituminous components (Table 2). The mix of particles is seen in the contrast in vitrinite reflectances, as seen in Figure 1. Coal LHP is high volatile A bituminous. In general, the vitrinite reflectance of the low-rank components could not be measured owing to the texture of the maceral assemblages, with the vitrinite generally being smaller than the measuring spot for the reflectance, and the difficulty in properly polishing both high- and low-rank particles in the same pellet. The mineral-free maceral assemblages are generally dominated by vitrinite-group macerals. Coals MBF-1 and HCH, each with over 12% inertinite-group macerals and over 5.8% liptinitegroup macerals (both on a mineral-free basis), are the exceptions. With 77.4% and 81.9% vitrinite, respectively, they are low vitrinite only in comparison to the other four coals and coal blends. 3.2.2 Fly ash petrology The fly ashes are dominated by the glass with over 25% coal-derived carbons along with small amounts of petroleum coke and incompletely burned coal (Table 3). The glass occurs as the vitrified edges of rock fragments (Figure 2 (A-B)) or as angular fragments (Figure 2 (C-D)). The carbons are represented by relatively unburned carbons, indicating some melting, but not enough heating to reach the coke stage (Figure 3). Isotropic chars result from the combustion of low-rank coal (Figure 4 (A)) and isotropic (Figure 4 (B)) and anisotropic cokes (Figure 4 (C-D)) result from the combustion of bituminous vitrinite. The differences between chars and cokes result from the fundamental differences between non-caking low-rank vitrinite and caking/coking, thermoplastic high volatile bituminous vitrinite26. Just as subbituminous and high volatile bituminous vitrinites are seen in the coal blends, a contrast in carbon types can be seen in the fly ashes (Figure 5). Petroleum coke-derived fly ash carbons were observed in both fly ashes (Figure 6). ACS Paragon Plus Environment

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3.3 XRD mineralogy The XRD of the coal and fly ash are shown in Figure 7. It is observed that the X-ray pattern varies with the chemical properties or types of the samples. The XRD of the raw coal samples (TRP and TRP-NECF) shows different peak which reveals their amorphous nature. However, the feed coal samples (MBF-1, MBF-2, HCH, and LHP) have some crystalline nature in comparison to the above raw coals. Minerals found in these coal samples are mainly kaolinite, quartz, haematite, pyrite, and calcite. Coal fly ash (CFA-1 and CFA-2) also reveals the presence of minerals such as quartz, haematite, and pyrite. 3.4 FE-SEM-EDS analysis of minerals in coals and CFA The FESEM study of the coal samples revealed different forms of sulphide nanominerals. The dominant nanominerals identified are calcite (CaCO3) (Figure 8 (A)), pyrite (FeS2) (Figure 8 (B)) and haematite (Fe2O3) (Figure 8 (C)). The EDS analysis revealed the presence of hazardous elements (viz. Ga, Zn, Ni, Pb, and Cd) along with the nanominerals (Figure 8 (D)). These elements are present in very minor proportions. The FESEM analysis of CFA revealed the presence of residual carbonaceous materials associated with different nanominerals (Figure 9 (A-B)). Pyrite is odserved in CFA-1 along with silicate. The fly ash contains high amount of glass particle (silicates) around 10.30-18.88% by weight. The EDS analysis revealed Al-Si-Fe-S and Al-Si-Mg-As compounds with a minor proportion of potentially hazardous elements (PHEs) including Hg, As, Pd, Cd, Sn, Ni, and Co in the fly ash samples (Figure 9 (C-D)). 3.5 Rare earth element compositions of the coals and combustion products 3.5.1 REY Geochemistry of coal The studied raw/feed coal samples and combustion products were normalised with the upper continental crust27 based on the detailed description of the suitability of UCC and NASC normalisation after Dai et al.28 (Figure 10). Yttrium (Y3+) is closely associated with lanthanides in its characteristics, such as its ionic radius and charge which are very similar/equal to that of Ho3+ 29,30

. Hence, yttrium is generally placed between isovalent Dy3+ and Ho3+ in normalized REY ACS Paragon Plus Environment

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plots31. Yttrium abundance in the studied coal is 0.19-0.60 ppm whereas in fly ash samples it varies between 2.2-2.3 (ppm) against a worldwide average of 2-50 ppm in bituminous coals and Clark value is 6 ppm32. The REY distribution patterns are coherent and show shale-like REY distribution patterns which do not display a distinct enrichment or depletion of LREEs and HREEs while exhibiting a North Atlantic Shale Composite (NASC)-like distribution pattern, indicating a source from sediment source region which is highly depleted in yttrium. In the studied samples, the total rare earth element contents (ΣREY) vary considerably. The ΣREY in raw coal samples ranges from 16.9-18.8 ppm whereas feed coal range from 14.8-28.8 ppm (brick making); 35.6-60.8 ppm (tea processing) and 267.1-299.6 ppm for fly ash samples (Table 4). These ∑REY abundances are considerably low when compared to average world hard coal (69 ppm), world low-rank coal (65 ppm), world coal (68 ppm), US coal (62 ppm), and China coal (138 ppm)33-35.

The fly ash samples also record slightly low ∑REY abundances when

compared to REY in world coal ashes (404 µg/g)28. The total REY contents of these samples except fly ash samples are lower than UCC (168.4 µg/g) and North American Shale Composite (NASC) (173.2 µg/g)36. The threefold classification of REE/REY as light REEs (LREE- La, Ce, Pr, Nd, and Sm), middle REEs (MREEs- Eu, Gd, Tb, Dy, and Y), and heavy REE (HREEs- Ho, Er, Tm, Yb, and Lu) is adopted in the present study to describe the fractionation in raw coal as well as combustion products30. The threefold classification of REY (LREE= La+Ce+Pr+Nd+Sm+Eu; MREE=Gd+Tb+Dy+Y; HREE=Ho+Er+Tm+Yb+Lu after Seredin and Dai

30

are adopted in the

present study which is more distinct to describe the coals than two-fold classification.

The

LREE/HREE of raw coal is in the range and vary from 12.3-14.0, whereas LREE/MREE range from 11.7 to 13.7 ppm. The LREE/HREE and LREE/MREE vary considerably in the combustion products from 8.2-13.5 and 5.1-13.9 respectively. These ratios indicate that the raw coal and combustion products have slight enrichment in LREE relative to HREE without any significant fractionation in REY as indicated by (La/Lu)N; (La/Sm)N; (Gd/Lu)N 1 were extracted (Table 5). PCA leads to a reduction of the initial dimension of the dataset to three components which explain 96.24% of the data variation. Variables having loadings of >0.5 are only considered to explain each factor (see bold values in Table 5). In details, principal component 1 (F1), which has the high loadings of physico-chemical properties such as sulphate sulphur (SS), pyritic sulphur (PS), Moisture (M), ash, fixed carbon (FC), C, and REE such as Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Nb, Cs, Ba, La, Ce, Nd, Sm, Eu, Gd, Dy, Ho, Tm, Lu, Ta, Pb, Th, U, and accounts for 73.36% of the variability. The high loading of Nb suggests that the trace and REEs are associated with the clay minerals found in the coal54. Y is mainly linked with terrigenous materials input and Y enriched natural waters. The high loadings of Y show that the other elements are associated in the terrigenous materials along with the Y-enriched natural waters present in the coal-bearing areas58. Pyrite, chalcopyrite, and sphalerite might be the predominant sources of Ni, Cu, and Zn59. Principal component 2 (F2), with 12.62% of the total variance of the data, is highly loaded by H, Zr, and Hf, which might be derived from sediments of terrigenous origin and to a lesser concentration, from the felsic and felsicintermediate rocks60. Principal component 3 (F3) with the total variance of 8.53% shows the loading of Volatile matter (VM), total sulphur (TS), and organic sulphur (OS). Hierarchal clustering analysis of trace and REEs along with the physical-chemical properties of the coal and fly ash samples shows seven classes of similarity (Figure 12). Sulfate sulphur and pyrite sulphur show relationship with the elements V, Cr, Co, Ga, Rb, Sr, Nb, Cs, Tm, Lu, Ta, and U. Close hierarchal relations are observed among the elements Sc, Ni, Cu, Zn, Y, Ba, La, Ce, Nd, Sm, Eu, Gd, Dy, Ho, Pd, and Th. Zirconium and Hf are found in separate hierarchal class which also revealed in the principal component analysis (Table 5).


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4. Conclusions The chemistry, mineralogy, and petrology of few of the industrial feed coals were studied. The high- sulphur Northeast Indian coals and their blends were generally used in tea and brick-making industries for energy generation. The feed coals are dominated by vitrinite group macerals. The coal fly ashes are dominated by the glass with incompletely burned coal. The XRD qualitative mineralogical study of the coals and coal fly ash identified the presence of major minerals such as kaolinite, pyrite, quartz, calcite, with variations with respect to the type of feed samples. The different forms of pyrite nanominerals were observed from FESEM. The nano-scale Haematite (Fe2O3) is also present in the feed coal. The FESEM-EDS analysis revealed the presence of potentially hazardous elements (viz. Ga, Zn, Ni, Pb, and Cd) along with the nanominerals. The residual carbonaceous materials associated with different nanominerals are confirmed by FESEM analysis. The EDS analysis revealed the presence of nanosphere of Al-Si-Fe-S and Al-Si-Mg-As compounds with a minor proportion of potentially hazardous elements (PHEs) including Hg, As, Pd, Cd, Sn, Ni, and Co in one fly ash samples. The REE abundances in these industrial feed coals and its combustion products differ considerably. These REY abundances are considerably low when compared to average world hard coal. However, the fly ash samples also record slightly low REY abundances when compared to world coal ash contents. The REY geochemical characteristics of samples both raw coals and combustion products are genetically linked to multiple factors which are controlled by source-rock and sedimentation environment influenced types. The PCA analysis of the basic chemical parameters and elemental data indicate that the association of the trace and RE elements with the mineral groups present in the coal and combustion residues. Hierarchal clustering analysis of trace and REEs along with the physicochemical properties of the coal and fly ash samples shows seven classes of similarity.


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Acknowledgments Authors are thankful for funding from CSIR, New Delhi (OLP-2003-WP-III). The assistance received from the owners of the industries during sampling is thankfully acknowledged. Authors express special thanks to Prof. Dady Dadyburjor (Assocate Editor) and anonymous reviewers for their constructive comments to improve the qualiy of manuscript.


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Figure 1:

Contrast between sub-bituminous coal particle (lower right) and high volatile A

bituminous coal (top) (TRP-NECF).


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Figure 2: (A) Rock fragment with thin glass edge (CFA-1), (B) Rock fragment with glass edge (CFA-1), (C) Glass (CFA-1), (D) Variety of glass forms (CFA-2).

Figure 3: (A) and (B) Unburned/uncoked bituminous-derived carbons which have gone through the thermoplastic stage but have not been heated to a temperature where the carbon passes to a form of low-T coke (CFA-2).


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Figure 4: (A) Char from the combustion of low-rank coal (CFA-1), (B) Isotropic coke (CFA-2), (C) Incipient anisotropy. This particle has a lower reflectance than (D), indicative of a shorter time or/and a lower T of coking (CFA-2), (D) Anisotropic coke (CFA-2).

Figure 5: (A) and (B) Low-rank-coal-derived char (labelled as char) and bituminous-coal-derived coke (CFA-1).


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Figure 6: (A) and (B) Petroleum coke-derived carbons (CFA-2).


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Figure 7: X-Ray Diffraction patterns of feed coal and fly ash samples (K=Kaolinite, Q=Quartz, C=Calcite, H=Haematite, P=Pyrite)


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A

B

C

D

Figure 8: FESEM/EDS of feed coals showing nanominerals: rod-shaped calcite (A), pyrite (B) hexagonal haematite (C), orthorhombic jarosite with hazardous elements (D).


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A

C

B

D

Figure 9: FESEM/EDS of CFA-1 (A), CFA-2 (B) showing nanominerals and associated hazardous elements (C), (D).

Figure 10: Inter-correlations between important geochemical attributes of feed coal and raw coal samples


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Figure 11: Upper continental crust normalised rare earth and yttrium distribution patterns of various raw and feed coals.


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Dendrogram

OS TS VM Hf Zr H FC C Pb Ni Ba Zn Cu Gd Eu Y Ho Dy Sm Nd La Th Sc Ce U Ga Cs Ash Cr V Co Nb Rb SS Ta Tm Lu M Sr PS 0.8672557

0.6672557

0.4672557

0.2672557

0.0672557

-0.132744

-0.332744

-0.532744

-0.732744

-0.932744

Similarity

Figure 12: Hierarchical clustering analysis (HCA) of trace and REEs in the coal and fly ash samples. ACS Paragon Plus Environment

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23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Table 1: Physico-chemical properties of the feed coal samples (as received wt. %)

Proximate analysis

Ultimate analysis

Forms of Sulphur

Sample

M

VM

Ash

N

O

TS

SS

PS

OS

3.50

54.30

5.62

36.58 81.10 4.54

1.01

6.59

6.86

0.27

0.14

6.45

2.40

41.14

2.19

54.27 81.00 5.63

1.10

8.68

3.59

0.10

0.36

3.13

MBF-1

4.76

50.14

14.43 30.66 73.70 3.27

1.01

17.4

4.62

0.68

0.49

3.45

MBF-2

3.82

52.11

11.46 32.61 82.00 5.08

0.98

9.14

2.80

0.26

0.12

2.43

HCH

5.68

44.11

23.39 26.81 63.70 3.88

1.20 26.94

4.28

1.05

0.67

2.56

LHP

6.34

51.06

19.25 23.35 66.50 4.54

1.00 24.03

3.93

1.03

0.47

2.43

TRP

FC

C

H

TRPNECF

(M= Moisture, VM= Volatile Matter, FC= Fixed Carbon, TS= Total Sulfur, SS= Sulfate Sulfur, PS= Pyritic Sulfur, OS= Organic Sulfur)


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Table 2: Maceral groups, vitrinite subgroups, and individual macerals on the mineral-included and mineral-free basis and minerals (all on volume % basis). Vitrinite maximum and random reflectances with the standard deviations of the reflectances and V-types. Note that the reflectance of the low-rank blend component could not be measured for some of the coal samples. TRP

TRP/NECF

MBF-1

MBF-2

HCH

LHP

telinite

15.2

14.3

13.2

15.4

17.0

15.0

14.6

15.9

10.2

15.8

3.9

6.0

collotelinite

55.9

52.2

58.5

40.0

44.3

66.5

53.2

58.3

31.3

48.5

50.0

76.5

total telovitrinite

71.1

66.5

71.7

55.4

61.3

81.5

67.8

74.2

41.5

64.3

53.9

82.5

vitrodetrinite

18.6

22.4

7.9

12.3

13.6

9.0

22.8

19.4

10.2

15.8

7.9

12.0

collodetrinite

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

18.6

22.4

7.9

12.3

13.6

9.0

22.8

19.4

10.2

15.8

7.9

12.0

corpogelinite

3.0

2.9

0.8

2.3

2.6

0.9

3.0

3.2

1.1

1.8

0.8

1.2

gelinite

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

total gelovitrinite

3.0

2.9

0.8

2.3

2.6

0.9

3.0

3.2

1.1

1.8

0.8

1.2

92.8

91.9

80.4

70.0

77.4

91.4

93.6

96.8

52.8

81.9

62.6

95.8

0.8

0.7

2.6

10.8

11.9

3.0

0.7

0.8

4.9

7.6

0.8

1.2

total detrovitrinite

total vitrinite fusinite


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Page 26 of 42

25

semifusinite

0.0

0.0

1.5

1.5

1.7

1.7

0.0

0.0

0.8

1.2

0.0

0.0

micrinite

0.0

0.0

0.4

0.0

0.0

0.4

0.0

0.0

0.4

0.6

0.0

0.0

macrinite

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

secretinite

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

funginite

0.0

1.5

1.1

1.9

2.1

1.3

1.5

0.0

1.1

1.8

0.0

0.0

inertodetrinite

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.8

1.2

0.0

0.0

total inertinite

0.8

2.2

5.7

14.2

15.7

6.4

2.2

0.8

7.9

12.3

0.8

1.2

sporinite

0.8

1.8

1.5

3.8

4.3

1.7

1.9

0.8

1.9

2.9

0.0

0.0

cutinite

0.8

1.5

0.0

1.2

1.3

0.0

1.5

0.8

1.5

2.3

0.4

0.6

resinite

0.4

0.4

0.4

0.8

0.9

0.4

0.4

0.4

0.0

0.0

1.6

2.4

alginite

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

liptodetrinite

0.4

0.0

0.0

0.4

0.4

0.0

0.0

0.4

0.4

0.6

0.0

0.0

suberinite

0.0

0.4

0.0

0.0

0.0

0.0

0.4

0.0

0.0

0.0

0.0

0.0

exsudatinite

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

total liptinite

2.3

4.0

1.9

6.2

6.8

2.1

4.1

2.4

3.8

5.8

2.0

3.0

silicate

4.2

0.7

9.8

6.2


29.4

31.5

Page 27 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

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26

sulfide

0.0

1.1

2.3

0.4

5.7

2.0

carbonate

0.0

0.0

0.0

0.0

0.0

0.0

other

0.0

0.0

0.0

3.1

0.4

1.2

total mineral

4.2

1.8

12.1

9.6

35.5

34.6

Rmax

0.60

0.66

0.62

0.63

0.69

0.77

st dev

0.09

0.03

0.05

0.14

0.09

0.05

Rrandom

0.56

0.62

0.56

0.60

0.65

0.73

st dev

0.08

0.03

0.04

0.13

0.09

0.04

v4

12

v5

36

6

36

32

8

v6

40

80

52

8

52

12

v7

12

14

12

24

24

52

16

12

36

v8

20


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Page 28 of 42

27

v9

4 *

*

*

(v4-v9 are the Vitrinite types of the coal)

* Low-rank components could not be measured


*

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28

Table 3: Fly ash petrology (v %)

CFA-1 glass

CFA-2

69.2

73.0

mullite

0.0

0.0

spinel

0.0

0.7

quartz

0.4

0.7

sulfide

0.0

t

rock fragment

4.0

0.0

isotropic coke

14.8

12.1

anisotropic coke

7.6

9.3

inertinite

3.2

1.8

pet coke

0.4

1.1

unburned coal

0.4

1.4


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29

Table 4: Trace and rare earth element concentration of feed coals and raw coal samples

Analyte (ppm) Sc

TRP-NECF

TRP

MBF-1

MBF-2

HCH

LHP

CFA-1

CFA-2

1.33

1.83

3.99

1.15

3.95

6.16

19.65

18.44

V

13.90

21.56

40.21

19.59

70.27

51.08

168.95

179.56

Cr

9.77

13.06

23.28

10.91

39.77

26.30

72.14

76.46

Co

2.89

3.43

6.83

2.77

9.66

6.33

20.37

24.04

Ni

63.41

43.33

66.68

61.68

83.67

109.37

83.81

116.15

Cu

71.56

47.31

73.21

62.73

79.65

85.03

84.14

99.59

Zn

121.38

71.01

104.28

110.95

137.04

145.56

126.77

162.21

Ga

0.09

0.13

0.22

0.13

0.38

0.32

1.42

1.52

Rb

7.00

7.52

17.41

8.24

30.51

30.77

72.03

68.91

Sr

178.10

159.73

178.47

144.52

263.25

235.44

779.78

486.33

Y

0.13

0.16

0.31

0.15

0.39

0.60

2.35

2.21

Zr

8.38

13.16

12.99

11.76

15.57

7.79

14.99

16.80

Nb

0.02

0.03

0.06

0.03

0.12

0.13

0.73

0.71

Cs

0.58

0.83

1.42

0.92

2.76

1.92

5.65

5.88

Ba

90.41

83.45

110.74

128.56

161.46

166.31

712.80

579.19

La

3.68

3.63

5.58

3.19

7.84

12.17

65.18

60.68

Ce

6.60

7.45

9.99

5.23

9.25

21.65

105.02

88.57

Pr

0.76

0.89

1.26

0.62

1.36

2.66

13.39

12.37

Nd

2.91

3.27

5.17

2.67

7.14

10.70

59.99

54.76

Sm

0.62

0.77

1.27

0.63

1.67

2.55

13.80

12.53


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30

Eu

0.13

0.16

0.30

0.14

0.39

0.57

2.51

2.31

Gd

0.41

0.50

0.90

0.40

1.19

1.74

8.19

7.41

Tb

0.07

0.09

0.17

0.07

0.23

0.33

1.53

1.37

Dy

0.49

0.65

1.19

0.51

1.67

2.25

10.45

9.59

Ho

0.10

0.13

0.25

0.11

0.35

0.47

2.18

1.96

Er

0.39

0.48

0.86

0.43

1.27

1.57

7.09

6.77

Tm

0.07

0.09

0.16

0.08

0.23

0.28

1.35

1.21

Yb

0.42

0.53

1.19

0.47

1.29

1.51

7.50

6.65

Lu

0.05

0.07

0.11

0.06

0.15

0.17

0.87

0.74

Hf

4.25

5.77

6.09

5.31

6.88

4.04

5.35

5.00

Ta

0.10

0.19

0.38

0.13

0.54

0.72

2.41

2.51

Pb

2.41

1.94

2.44

2.55

3.21

4.92

4.74

5.45

Th

0.71

0.80

1.68

0.24

1.68

2.55

19.02

16.16

U

0.89

0.99

1.18

1.05

1.51

1.36

6.33

6.04

∑REY(ppm)

16.87

18.85

28.79

14.81

35.59

60.82

267.08

299.64

LREE/HREE

14.03

12.24

9.04

10.77

8.31

12.43

13.21

13.56

13.10

11.70

8.91

10.64

5.94

7.71

12.48

12.51

(La/Lu)N

0.78

0.56

0.54

0.57

0.55

0.75

0.80

0.88

(La/Sm)N

0.88

0.71

0.66

0.75

0.71

0.72

0.71

0.73

(Gd/Lu)N

0.69

0.61

0.68

0.56

0.67

0.84

0.80

0.85

(Eu/Eu*)N

1.19

1.17

1.33

1.29

1.31

1.26

1.11

1.13

(Ce/Ce*)N

0.88

0.94

0.81

0.78

0.54

0.83

0.73

0.67

LREE/MRE E


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31

(La/La*)N

1.25

0.97

1.39

1.86

10.92

1.34

2.09

1.99

Th/U

0.80

0.81

1.42

0.23

1.21

1.87

2.68

3.01

Note: Pr, Tb, Yb concentrations are extrapolated since certified values are not available Eu, Ce, and La anomalies are calculated after Bau and Dulski (1996)

37

by using the formulas as

given below Eu/Eu* = Eu/(SmN x GdN)1/2 ; Ce/Ce* = CeN/(LaN x PrN)1/2 ; La/La* = LaN/(3PrN – 2NdN)


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32

Table 5: Matrix of the first three principal components of the physico-chemical parameters, trace elements and REEs. Component

F1

F2

F3

TS

0.021

0.330

0.402

SS

0.965

0.034

0.000

PS

0.632

0.021

0.167

OS

0.253

0.196

0.384

M

0.912

0.016

0.027

VM

0.006

0.049

0.673

Ash

0.828

0.072

0.019

FC

0.578

0.101

0.092

C

0.857

0.002

0.129

H

0.277

0.478

0.019

Sc

0.880

0.005

0.071

V

0.845

0.120

0.027

Cr

0.772

0.164

0.051

Co

0.718

0.200

0.056

Ni

0.817

0.176

0.003

Cu

0.662

0.134

0.150

Zn

0.551

0.227

0.215

Ga

0.912

0.061

0.017

Rb

0.988

0.004

0.003

Sr

0.795

0.004

0.058

Y

0.932

0.025

0.043


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 34 of 42

33 Zr

0.001

0.937

0.040

Nb

0.988

0.002

0.002

Cs

0.810

0.116

0.049

Ba

0.792

0.010

0.031

La

0.888

0.062

0.042

Ce

0.638

0.156

0.197

Nd

0.915

0.035

0.045

Sm

0.914

0.028

0.056

Eu

0.949

0.014

0.035

Gd

0.938

0.017

0.042

Dy

0.963

0.005

0.029

Ho

0.965

0.006

0.027

Tm

0.983

0.000

0.014

Lu

0.983

0.002

0.014

Hf

0.009

0.924

0.059

Ta

0.968

0.000

0.031

Pb

0.723

0.229

0.021

Th

0.840

0.006

0.059

U

0.877

0.080

0.016

Eigenvalue

29.346

5.052

3.415

Variability (%)

73.366

12.629

8.538

Cumulative %

73.366

85.995

94.533


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Energy & Fuels

34

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