Subscriber access provided by UNIV OF ESSEX
Article
Distribution of trace elements in fractions after micronization and density-gradient centrifugation of high-Ge coals from the Wulantuga and Lincang Ge ore deposits, China Qiang Wei, Susan M. Rimmer, and Shifeng Dai Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b02118 • Publication Date (Web): 02 Oct 2017 Downloaded from http://pubs.acs.org on October 2, 2017
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Energy & Fuels is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 51
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
Energy & Fuels
1
Distribution of trace elements in fractions after micronization and
2
density-gradient centrifugation of high-Ge coals from the Wulantuga and
3
Lincang Ge ore deposits, China
4 5 6 7 8
Qiang Weia,b, Susan M. Rimmerc, Shifeng Daia,b,d* a
State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, China b
9 10
College of Geoscience and Survey Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
11 12
c
Department of Geology, Southern Illinois University Carbondale, Carbondale, IL 62901, United States
13 14
d
School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, China
15
Corresponding author:
[email protected] 16 17 18 19
Abbreviations: DGC, density-gradient centrifugation; WLTG, Wulantuga Ge ore deposit; LC, Lincang Ge ore deposit; REY, rare earth elements and yttrium; LREY, light rare earth elements and yttrium; MREY, medium rare earth elements and yttrium; HREY, heavy rare earth elements and yttrium; UCC, upper continental crust.
20
ABSTRACT
21
The Wulantuga (Inner Mongolia) and Lincang (Yunnan Province) germanium ore deposits in
22
China are both considered world-class, coal-hosted Ge deposits. For this paper, two bench coals
23
(WLTG C6-2 from Wulantuga and LC S3-6 from Lincang) were selected to characterize the
24
associations between density fractions (maceral concentrates) and trace elements using
25
micronization, density-gradient centrifugation (DGC), and inductively coupled plasma mass
26
spectrometry (ICP-MS), especially for the abnormally enriched trace elements (including Ge, W,
27
As, Sb, Be, U, and Nb) and rare earth elements and yttrium (REY) in the Wulantuga and/or
28
Lincang high-Ge coals that are widely considered to have varying degrees of organic affinity.
1
ACS Paragon Plus Environment
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 2 of 51
29
Huminite and inertinite contents of WLTG C6-2 account for 58.4% and 40.7%, respectively,
30
whereas LC S3-6 is dominated by huminite (98.7%). Lower peak densities for huminite/inertinite
31
and Gaussian distributions of DGC profiles after HCl-HF demineralization suggest that some
32
minerals still exist in the micronized fractions. Many trace elements that are typically thought to
33
have organic affinities decrease significantly after HCl-HF demineralization suggesting a mode of
34
occurrence that is susceptible to acid leaching (i.e., weakly bonded to organic matter).
35
In the Wulantuga high-Ge coal, Be and As are preferentially enriched in inertinite-rich
36
density fractions, perhaps due to association with minerals in the heavier fractions. Higher Ge
37
contents are seen in huminite fractions relative to inertinite, possibly due to differences in sites
38
capable of holding Ge. Antimony is slightly more enriched in huminite-rich fractions. A positive
39
Ge-W correlation and variable W concentrations across the density profile suggest a mixed
40
organic-inorganic affinity for W, and Nb shows a similar distribution to W. Barium is
41
predominantly associated with minerals. In the Lincang S3 seam, Ge concentration increases
42
versus fraction density, probably due to the availability of more bonding sites in denser huminite
43
macerals. The preferential enrichments of Be, U, and Sb in heavier fractions could be due to more
44
bonding sites in denser huminites and/or their inorganic affinities. Arsenic content generally varies
45
smoothly across DGC fractions, and most pyrite particles where at least part of the As occurs were
46
removed in the DGC process. Tungsten, Nb, and possibly Th may occur in similar phases due to
47
their comparable variation trends. In addition, REY anomalies in some fractions mainly result
48
from elevated LREY, and REY (especially LREY) in WLTG C6-2 and LREY in LC S3-6 may
49
occur in minerals with some trace elements, including Sc, Sr, and Ba.
50
Keywords: high-Ge coal, trace elements, macerals, micronization, density-gradient centrifugation. 2
ACS Paragon Plus Environment
Page 3 of 51
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
Energy & Fuels
51
1. INTRODUCTION
52
The Wulantuga (Inner Mongolia) and Lincang (Yunnan Province) high-Ge coal deposits in China
53
are both world-class coal-hosted germanium deposits that are of substantial scientific and
54
economic value.1,2 Trace elements occur primarily in inorganic associations within the coal, but
55
increasingly, important organic associations for certain trace elements are being recognized. Based
56
on recent in-depth geochemical studies, abnormally enriched trace elements including Ge, W, As,
57
and Sb in Wulantuga high-Ge coals and Ge, W, As, Sb, Be, U, Nb, and REY in Lincang high-Ge
58
coals, are presumed to be associated with organic matter to varying degrees.1,2 Li et al.3 separated
59
six density fractions (from 2.8 g/cm3) from two high-Ge coals from Wulantuga and
60
Lincang using float-sink techniques and investigated the modes of occurrence of the enriched
61
elements. Their work demonstrated that Be, B, Ge, Nb, Mo, Sb, W, and U in the Lincang coal, and
62
B, Ge, Nb, W, Sb, Na, and Mg in the Wulantuga coal have strong organic affinities. Other studies
63
also have suggested organic affinities for Ge, W, B, and Mo in the Wulantuga high-Ge coals4-6 and
64
Ge, W, Ga, Se, Sb, Au, Hf, Ta, and K in the Lincang high-Ge coals7-9 based primarily on negative
65
correlations between ash yield and trace element concentrations or other methods (e.g., density
66
fractions, chemical extraction). A recent study by Etschmann et al.,10 using the cutting-edge
67
technique of MSXRF (Mega-pixel Synchrotron X-ray Fluorescence) coupled with XANES and
68
EXAFS to determine the occurrences of selected enriched trace elements (Ge, As, and W) in the
69
Wulantuga and Lincang high-Ge coals, also suggested a major organic affinity for Ge and W. In
70
addition, they found that Ge exists primarily in the tetravalent oxidation state and in a distorted
71
octahedral coordination with O, and W(VI) is strongly bonded to organics, similarly to Ge(IV).
3
ACS Paragon Plus Environment
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
72
Page 4 of 51
A few preliminary studies have attempted to further clarify the relationships between trace
73
elements and macerals in high-Ge coals. Zhuang et al.11 suggested that Ge in the Lincang coal is
74
predominantly incorporated in huminite, especially corpohuminite. Considering the predominance
75
of huminite in the Lincang high-Ge coals (over 90%),2 it is reasonable to speculate that the
76
enriched trace elements with strong organic affinities are primarily associated with huminite. In
77
the Wulantuga high-Ge coals that contain an average of 46.8% huminite and 52.5% inertinite,1 a
78
positive correlation is observed between huminite content and Ge concentration (Figure 1).1,12 A
79
similar positive correlation between huminite and Ge was reported for bench samples of the
80
Wulantuga and Lincang coals by Wei and Rimmer.13 However, more research is necessary to fully
81
understand the associations between the trace elements and macerals in these high-Ge coals.
82
Mineral matter, including discrete crystalline mineral particles, poorly crystalline mineraloids,
83
and non-mineral inorganics,14 are potential sites for trace elements. No Ge-bearing minerals were
84
detected by petrographic analysis, XRD, or SEM-EDX in the Wulantuga and Lincang coal
85
samples and their corresponding low-temperature ashes,1,2 and EPMA and PIXE analyses did not
86
detect any Ge-bearing minerals in the Lincang high-Ge coals.11 However, in one study some minor
87
fine-grained Ge-bearing oxides were reported in the Wulantuga high-Ge coal.4 Previous studies on
88
the organic affinity of trace elements in the Wulantuga and Lincang high-Ge coals did not consider
89
the potential for minor mineral contamination of organic-rich fractions acquired by float-sink
90
techniques.3,11 The presence of minerals, which are heavier than organic matter, can influence
91
density and may result in uncertainties about element affinities. Therefore, the interference of
92
minerals must be taken into account in the studies on trace element affinities of high-Ge coals.
4
ACS Paragon Plus Environment
Page 5 of 51
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
Energy & Fuels
93
Density-gradient centrifugation (DGC) is widely used for maceral separation15-18 and has
94
been used to assess the affinity of trace elements in coal.19 This approach can produce more
95
accurate and systematic density fractions than simple float-sink techniques.15 Previous studies did
96
not provide direct evidence for a relationship between macerals and Ge or other trace elements in
97
the high-Ge coals. In this study, DGC was used to separate micronized Wulantuga and Lincang
98
high-Ge coals into different density fractions (maceral concentrates) to characterize the
99
relationships between macerals and trace elements in an attempt to provide new perspectives on
100
the distribution and affinity of trace elements.
101
2. GEOLOGICAL SETTINGS
102
The Shengli Coalfield (45 km long and 7.6 km wide) developed in the fault-controlled Shengli
103
sub-basin of the Erlian Basin in northeastern Inner Mongolia, northern China. The Wulantuga Ge
104
deposit is located in the southwest end of the Shengli Coalfield and covers an area of 2.2 km2
105
(Figure 2A,B).20 In the study area, the lower portion of the Shengli Formation, which is deposited
106
in the Lower Cretaceous sequence, is the major coal-bearing interval with an average thickness of
107
368 m. Among the eight coal beds (Nos. 5, 5-lower, 6-upper, 6, 6-lower, 7, 8, and 9) in the
108
Shengli Formation, the No. 6 Coal is the major coal seam that has an average thickness of 16.1 m
109
and an average maximum huminite reflectance of 0.45%.1
110
The Bangmai Basin (western Yunnan, southwestern China) is an asymmetric half-graben
111
controlled by NW and EW-trending faults (Figure 2C),2 and is filled by the Miocene coal-bearing
112
Bangmai Formation where the Lincang Ge deposits developed. The Bangmai Formation was
113
deposited on a basement of middle Triassic granitic batholiths, can be divided into six zones from
5
ACS Paragon Plus Environment
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 6 of 51
114
top to bottom (N1b6 to N1b1). The lignites occur in zones N1b2, N1b4-5, and N1b6, and the Ge-rich
115
lignites occur in the lower zone, N1b2.2,21 At the Dazhai Mine in the Lincang deposit, the average
116
random huminite reflectances of the three Ge-rich coal seams (upper S3, middle Z2 and lower X1)
117
are 0.34%, 0.38%, and 0.46%, respectively.2
118
3. SAMPLING AND ANALYTICAL METHODS
119
Two lignite bench samples, WLTG C6-2 (huminite maximum reflectance of 0.44%)1 and LC S3-6
120
(huminite random reflectance of 0.32%),2 were collected from the Early Cretaceous No. 6 Coal at
121
the Wulantuga high-Ge coal deposit in the Shengli Coalfield, Inner Mongolia by Dai et al.,1 and
122
the Neogene upper seam of the Dazhai Mine at the Lincang high-Ge coal deposit in the Bangmai
123
Basin, Yunnan Province by Dai et al.,2 respectively. Each sample, representing a 10-cm x 10-cm
124
area of the coal face, was stored immediately in plastic bags to minimize contamination and
125
oxidation. The two samples were air dried and crushed to minus 20-mesh for petrographic analysis
126
and minus 200-mesh for micronization. Micronization and demineralization techniques followed
127
those of Wei and Rimmer.13 WC vessels, which could influence the measured W contents, were
128
not used in sample preparation. These particular samples were selected for the current DGC study
129
as previous work had shown that they contain elevated concentrations of trace elements and show
130
a range in petrographic composition.13
131
3.1. Micronization
132
To liberate macerals from each other and to ensure effective exposure of mineral matter to
133
acids during subsequent demineralization, a Sturtevant micronizer (fluid energy mill) was used to
134
further grind the minus 200-mesh samples to ~ 3 µm. The feed speed was controlled using a FMC
6
ACS Paragon Plus Environment
Page 7 of 51
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
Energy & Fuels
135
Syntron PowerPulse Electric Controller, and the feed pressure and grinding pressure were set to
136
100 psi and 120 psi, respectively. Compressed nitrogen was employed as the carrier gas to avoid
137
oxidation.
138
3.2. Demineralization
139
3 g of each micronized coal was placed in a 50 ml Nalgene test tube and allowed to react
140
with 40 ml of 6N HCl (TraceMetal Grade) for 2 hrs (Brij-L23 solution was added as a surfactant
141
to help wet the samples), followed by a rinse with deionized water and another treatment with 6N
142
HCl. This was followed by a second series of washes with deionized water and treatment with 30
143
ml of 48% HF (TraceMetal Grade) for 48 hrs before additional deionized water washes.
144
Afterwards, a third 6N HCl treatment was followed by washes with deionized water to neutral pH
145
and then the samples were dried overnight at 50°C. Nitric acid was not used in the current study as
146
it could alter the organic matter.22,23
147
3.3. Density-gradient centrifugation (DGC)
148
DGC was performed using a BECKMAN COULTER Avanti J-26 XPI centrifuge. A gradient
149
was created using CsCl and deionized water, and a few drops of 30% Brij-L23 solution was used
150
as a surfactant. Each sample was centrifuged for 2 hrs at 8,000 rpm, and then the gradient was
151
pumped out and collected in fractions using a PAAP-DMA 45 densitometer and a Foxy 200
152
fractionator. Once separated, each fraction was filtered using 0.22 µm Millipore filters and rinsed
153
repeatedly with deionized water. The procedure was modified from that of Dyrkacz and Horwitz.15
154
In the present study, 18 fractions were obtained for each sample across their range of density
7
ACS Paragon Plus Environment
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 8 of 51
155
(micronized WLTG C6-2, 1.3306-1.5598 g/mL; demineralized WLTG C6-2, 1.2411-1.5912 g/mL;
156
micronized LC S3-6, 1.3353-1.5189 g/mL; and demineralized LC S3-6, 1.2139-1.4864 g/mL).
157
3.4. Petrographic analysis
158
To prepare pellets for petrographic analysis, a representative split of minus 20-mesh raw coal
159
sample, micronized sample, minus 200-mesh coal sample, or DGC fraction sample was mixed
160
with epoxy resin and hardener. Due to the very small amounts of material available for the DGC
161
fractions, micro pellets were prepared where a small well was drilled into a blank epoxy pellet for
162
the coal/epoxy mix. Pellets were processed using a Buehler Automet 250 grinder/polisher and
163
polished using 320 grit, 400 grit, and 600 grit abrasive papers, and then 1.0 µm (alpha alumina)
164
and, finally, 0.06 µm (colloidal silica) polishing compounds (following methods modified from
165
Pontolillo and Stanton24). Macerals (huminite, inertinite, and liptinite) were determined using a
166
Zeiss Universal microscope in reflected white- and blue-light illumination, under oil immersion;
167
500 points for each raw coal sample pellet were counted to characterize the maceral composition.
168
The maceral groups in the DGC fractions can be recognized based on their distinct reflectances,
169
but it was difficult to identify individual macerals due to the small size of the micronized coal
170
particles.
171
3.5. Inductively coupled plasma mass spectrometry (ICP-MS)
172
Trace element concentrations were determined using a Thermo Fisher, X series II ICP-MS.
173
50 mg of each minus 200-mesh coal sample or DGC fraction sample was digested using an
174
UltraClave Microwave High Pressure Reactor (Milestone), with 5 ml 65% HNO3 and 2 ml 40%
175
HF employed as digestion reagents (GR acids further purified by sub-boiling distillation), as
8
ACS Paragon Plus Environment
Page 9 of 51
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
Energy & Fuels
176
outlined by Dai et al.25 Multi-element standards (Inorganic Ventures: CCS-1, CCS-4, CCS-5, and
177
CCS-6) were used for calibration of trace element concentrations. Collision/reaction cell
178
technology (CCT) of ICP-MS was used to determine As and Se concentrations in order to avoid
179
interference by polyatomic ions.26
180
4. RESULTS AND DISCUSSION
181
4.1. Maceral composition
182
The huminite and inertinite contents of WLTG C6-2 are 58.4% and 40.7%, respectively,
183
whereas LC S3-6 is dominated by huminite (98.7%). The liptinite maceral content of WLTG C6-2
184
is minimal (0.8%) as are the inertinite (1.3%) and liptinite (0%) contents of LC S3-6 (Table 1).
185
The huminite macerals of WLTG C6-2 are mostly ulminite, densinite, and attrinite, and the
186
gelinite, textinite, and corpohuminite contents are low. Fusinite is the most abundant inertinite in
187
WLTG C6-2, followed by inertodetrinite, semifusinite, and minor funginite and macrinite. Only
188
very small amounts of resinite and cutinite can be observed in WLTG C6-2. The dominant
189
huminite macerals of LC S3-6 are densinite and ulminite, and gelinite followed by textinite,
190
attrinite, and corpohuminite. Funginite is the only observable inertinite in LC S3-6.
191
4.2. Maceral separation
192
Micronization assured subsequent reliable demineralization and maceral separation, although
193
some particles > 10 µm were still present after micronization (Figure 3). Poe et al.27 suggested that
194
DGC maceral separations performed on minus 100-mesh coal can also produce repeatable results.
195
However, micronization is crucial in the present study because grinding samples to minus
9
ACS Paragon Plus Environment
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 10 of 51
196
200-mesh did not adequately separate macerals from each other (Figure 4A,B) or isolate minerals
197
from the organic matter (Figure 4C,D).
198
Based on the density data (Table 2), DGC profiles are shown in Figure 5 along with
199
photomicrographs of the two micronized samples and their corresponding
200
micronized-demineralized samples. The densities for huminite and inertinite of
201
micronized-demineralized WLTG C6-2 are around 1.36 g/mL and 1.44 g/mL, respectively.
202
Without acid demineralization (micronized WLTG C6-2), these densities are somewhat higher,
203
around 1.43 g/mL and 1.49 g/mL, respectively. The density of huminite in the
204
micronized-demineralized LC S3-6 is around 1.35 g/mL; in the sample that was micronized but
205
not demineralized, the density is higher at 1.46 g/mL. The lower peak densities after
206
demineralization suggest that finely dispersed mineral matter associated with the organic matter
207
can influence the DGC fraction densities, which makes sense considering that clays and quartz
208
have densities of 2.6 to 2.8 g/mL and 2.65 g/mL, respectively. Thus, even small amounts of
209
mineral contaminants can result in the huminite and inertinite reporting to denser fractions. Minor
210
amounts of minerals (pyrite) can still be observed in some micronized-demineralized fractions,
211
suggesting even lower actual maceral densities than those displayed in Figure 5B,D. Nitric acid
212
was not utilized to further remove pyrite because of its potential to alter the organics.22,23
213
Compared to the micronized DGC profiles (Figure 5A,C), those of micronized-demineralized
214
samples are closer to Gaussian distributions (Figure 5B,D) due to the removal of mineral matter
215
that can skew the density distributions. Qualitatively, it does appear that the average particle size
216
in denser DGC fractions are larger than those in less-dense fractions, especially for the Lincang
10
ACS Paragon Plus Environment
Page 11 of 51
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
Energy & Fuels
217
coal (Figure 5A-D), perhaps suggesting slight differences in hardness and the effectiveness of
218
micronization.
219
Li et al.3 obtained six density fractions (ρ < 1.43, 1.43-1.6, 1.6-2.0, 2.0-2.4, 2.4-2.8, and > 2.8
220
g/cm3) for the Wulantuga and Lincang high-Ge coals using float-sink techniques. As these authors
221
used minus 200-mesh, untreated coal (i.e., acid demineralization was not used), it was difficult to
222
define the density ranges of the organic matter and the density boundary between organic matter
223
and minerals. As a result, it was hard to determine the organic/inorganic affinities of trace
224
elements, let alone their associations with macerals. The present study aims to help us better
225
understand the relationships between macerals and trace elements in the high-Ge coals from China,
226
especially for those enriched ones.
227
4.3. Distribution of trace elements
228
4.3.1. Trace element concentrations
229
Compared to the average concentrations of elements in world low-rank coals,28 enrichments
230
(where the concentration coefficient > 5, concentration coefficient classification used here as
231
proposed by Dai et al.29) are seen for Be, Ge, As, Sb, Cs, Ba, W, and Eu in the micronized WLTG
232
C6-2 coal, and Be, Zn, Ge, As, Nb, Cd, Sn, Sb, Cs, W, Tl, and U in the micronized LC S3-6 coal
233
(Table 3). Most of these elements can be removed by HCl-HF leaching (reduction rate > 50%;
234
Table 3), where RR (reduction rate, %) = (concentration in Micro - concentration in Demin) /
235
concentration in Micro * 100%. Most of the trace elements, including Ge, W, As, and Sb in the
236
Wulantuga coal and Ge, W, As, Sb, Be, U, Nb, and REY in the Lincang coal, that are widely
237
considered to have organic affinities to varying degrees are significantly decreased following
11
ACS Paragon Plus Environment
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 12 of 51
238
demineralization (e.g., Ge reduction rate is 95-96%; Table 3 and Figure 6). This suggests a mode
239
of occurrence that is susceptible to acid dissolution. Wei and Rimmer13 proposed this may be due
240
to weak bonds between these elements and organic matter (as they may occur in the form of
241
chelates), thus allowing them to be removed by HCl-HF. Discussion of the distribution of these
242
trace elements in the micronized-demineralized macerals is less informative as the concentrations
243
have been reduced by acid demineralization and, in several cases, are below detection limits in the
244
feed sample, let alone in the DGC fractions. Thus, the following discussion will focus on the trace
245
element distributions in the DGC fractions obtained from the micronized coal sample that has not
246
been demineralized.
247
Due to the use of CsCl in the DGC process, Cs concentrations in the DGC fractions are
248
extremely high (up to > 25,000 µg/g) although each fraction had been rinsed thoroughly using
249
deionized water. Technically, Cs in the DGC fractions can be from both the coal and CsCl. The Cs
250
values in the micronized WLTG C6-2 and LC S3-6 are low (5.04 µg/g and 17.8 µg/g, respectively;
251
Table 3). Thus, Cs in the original coal is negligible compared to the extremely high Cs
252
concentrations observed in the DGC fractions. To remove the influence of Cs on the concentration
253
of other elements, the trace element contents of DGC fractions are recalculated to a Cs-free basis
254
(Tables 4 and 5) by excluding Cs and regarding the sum of all other elements equal to 100%.
255
4.3.2. Distribution of trace elements
256
The trace element concentrations of each DGC fraction were determined by ICP-MS (Tables
257
4 and 5). Based on the degree of "smoothness" of plots of concentration versus density, the trace
258
elements from the micronized WLTG C6-2 and LC S3-6 were divided into two groups, "smooth"
12
ACS Paragon Plus Environment
Page 13 of 51
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
Energy & Fuels
259
and "variable" (Figures 7-10 and Table 6). The maceral composition of DGC fractions varies with
260
density continuously and gradually; thus, in theory, trace elements associated with different
261
macerals should show concentrations that also vary gradually with density, unless they are
262
associated with mineral matter to a certain degree.
263
In the present study, the four criteria were used to interpret element associations. (a)
264
Observations from previous studies. The consensus (e.g., a primary organic affinity for Ge) as
265
derived from numerous studies, including the investigations by Dai et al.1,2 who used the same
266
samples as those analyzed in this study. (b) Comparison of element concentrations in DGC
267
fractions to those in the corresponding micronized coal. Lower concentrations of a certain element
268
in the DGC fractions relative to the micronized coal would suggest an inorganic affinity to some
269
extent, because some minerals associated with this element could have been removed in the DGC
270
process. (c) Degree of “smoothness” of plot of element content versus density. Group 1 elements,
271
or those with “smooth” plots (Figures 7 and 9), may have a predominantly organic affinity, or the
272
minerals with which they are mainly or partly associated are evenly distributed across the density
273
fractions. For Group 2 elements, or those with a more “variable” plot of concentration vs. density,
274
at least some are likely to be associated with mineral particles that are unevenly distributed in the
275
DGC fractions, resulting in abrupt changes in trace element concentrations across the density
276
profile (Figures 8 and 10). (d) Relationship between elements. The organic association of an
277
element can be inferred by the direct correlation across DGC fractions between this element and
278
another element that is widely considered to be of organic affinity (e.g., Ge).
279
4.3.2.1. Wulantuga high-Ge coal
13
ACS Paragon Plus Environment
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
280
Page 14 of 51
Based on the DGC results (Table 2), DGC profiles, and fraction photomicrographs (Figure
281
5A), the density boundary between huminite and inertinite for micronized WLTG C6-2 is around
282
1.45 g/mL. This boundary is between two adjacent fractions that are huminite-rich (fraction at
283
1.4443 g/mL) and inertinite-rich (fraction at 1.4596 g/mL), respectively. With increasing density,
284
Be concentration in the DGC fractions also increases (Figure 7). Germanium concentration in
285
huminite increases with density and then decreases in inertinite, and Ge is generally higher in
286
huminite than in inertinite (Figure 7). Arsenic basically increases with density (Figure 7).
287
Antimony content in huminite is slightly higher than that in inertinite (Figure 7). Tungsten in
288
huminite is also generally higher than in inertinite, and it shows a pronounced variation with
289
density (Figure 8). Compared to other fractions, Ba is relatively high at 1.3692 g/mL and 1.4596
290
g/mL (Figure 8).
291
Beryllium in coal can be associated with organic matter and clay minerals,30,31 and elevated
292
Be is mostly organically bound.30 Dai et al.1 suggested that Be in the Wulantuga high-Ge coals has
293
a major inorganic affinity, although Be is highly elevated. In the present study, Be is preferentially
294
enriched in inertinite (Figure 7), and it may be due to the presence of more minerals in heavier
295
fractions. Lower Be concentrations in DGC fractions (Table 4 and Figure 7) relative to the
296
micronized coal (11.3 µg/g; Table 3) also suggest its inorganic affinity because some minerals that
297
Be is associated with were removed in the DGC process.
298
All previous studies have suggested that Ge in the coal-hosted Ge ore deposits at Wulantuga,
299
Lincang, and Spetzugli (Russian Far East) is associated mainly with organic matter.1,4-6,32-34
300
Smooth variation (Figure 7) and comparable concentrations in DGC fractions (122-204 µg/g;
301
Table 4) to that of micronized coal (188 µg/g; Table 3) support a major organic affinity for Ge. 14
ACS Paragon Plus Environment
Page 15 of 51
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
Energy & Fuels
302
Slightly higher Ge contents in huminite could be explained from the perspective of organic
303
structure. Huminite has more bonding sites for organically associated Ge than inertinite;
304
furthermore, compared to lighter huminite fractions, the preferential enrichment of Ge in denser
305
huminite macerals could be due to their denser structures that contain more bonding sites.
306
Antimony in coal generally occurs in sulfides,35,36 but it can also be associated with organic
307
matter.37 Arsenic in coal is generally associated with pyrite.38-44 Less commonly, it can occur also
308
in Tl-As sulfide,45,46 getchellite,36 clay minerals,35 phosphate minerals,35 and arsenic minerals;47
309
occurrences of organically-associated As have also been reported.48,49 Dai et al.1 suggested that As
310
and Sb in the Wulantuga high-Ge coals are associated with both organic matter and pyrite. Arsenic
311
tends to be more associated with heavier fractions (inertinites) because minerals (especially pyrite)
312
are more likely associated with denser fractions. A much higher As concentration in the
313
micronized coal (887 µg/g; Table 3) than in the DGC fractions (Table 4 and Figure 7) also
314
suggests an inorganic affinity because most pyrite that contains As was separated from the organic
315
matter in the DGC process. Antimony is slightly more enriched in huminite relative to inertinite,
316
and shows a 52% of reduction rate (Table 3), suggesting a mixed organic-inorganic affinity. A
317
positive Ge-Sb correlation and negative Ge-As correlation (Figure 11B,C) suggest a higher
318
organic affinity for Sb relative to As.
319
Tungsten in coal generally occurs in organic matter and oxide minerals,37,50 and the enriched
320
W in the Wulantuga, Lincang, and Spetzugli Ge ore deposits occurs primarily in organic
321
matter.1,2,32,33 The positive Ge-W correlation (Figure 11A) in the present study also supports its
322
organic affinity. However, as mentioned above, the pronounced variation in W with density and
323
higher concentration in the micronized coal (159 µg/g; Table 3) relative to those in DGC fractions 15
ACS Paragon Plus Environment
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 16 of 51
324
(Table 4 and Figure 8) suggest an inorganic affinity to some extent. In fact, some W in the
325
Wulantuga high-Ge coals occurs in quartz and chlorite.1 In addition, a positive W-Nb correlation
326
(Figure 11D) and their similar trends (maxima at the densities of 1.4074 g/mL, 1.4596 g/mL, and
327
1.5220 g/mL; Figure 8), suggest a similar mode of occurrence, although W is enriched but Nb is
328
depleted in WLTG C6-2.
329
Barium in coal can be both organically and inorganically associated.37,51-54 Barite (BaSO4)
330
was observed in the bench sample WLTG C6-2 by Wei and Rimmer13 and considered to be the
331
major carrier of Ba. Barium concentration in the micronized WLTG C6-2 is high at 2826 µg/g, but
332
it decreases by 64% to 1011 µg/g after HCl-HF leaching (Table 3), suggesting a major inorganic
333
affinity and minor association with organic matter and/or acid-resistant minerals. Compared to the
334
average Ba concentration in world low-rank coals (150 µg/g28), the much lower Ba concentrations
335
in micronized DGC fractions (Table 4 and Figure 8) further suggest its primary association with
336
minerals, because a significant proportion of the minerals were separated from the organic matter
337
during the DGC procedure due to their higher densities (e.g., density of barite is 4.48 g/cm3). The
338
relatively high Ba concentrations at 1.3692 g/mL and 1.4596 g/mL (Figure 8) are due to the
339
presence of Ba-bearing minerals, probably barite.
340
In addition, Li, Sc, Zn, Sr, and Ba show anomalously high values in the 1.3692 g/mL fraction
341
(Figure 8); in the 1.4596 g/mL fraction, Li, Sc, Rb, Sr, Ba, Th, and U show an increase (Figure 8).
342
Similarities in variations also suggest a Li-Sc-Sr-Ba assemblage (note that Ba and Sc show a
343
positive correlation; Figure 11F), and at least a portion of these elements may occur in mineral
344
particles, hence the uneven distribution across the density profiles. Additionally, Zn, Rb, Th, and
345
U could also exist in these minerals. Chromium and Ni show significant increases at 1.4871 g/mL; 16
ACS Paragon Plus Environment
Page 17 of 51
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
Energy & Fuels
346
similarities in their trends across the density profile (Figure 8) and the positive correlation between
347
them (Figure 11E) suggest they are associated with the same inorganic phases.
348
4.3.2.2. Lincang high-Ge coal
349
The peak density for huminite in the micronized LC S3-6 sample is around 1.46 g/mL
350
(Figure 5C). Beryllium, Ge, Sb, and U generally increase with increasing density (Figure 9).
351
Arsenic is generally more enriched in less dense huminite fractions, and its concentration varies
352
gradually with density and dips at 1.4175 g/mL (Figure 9). Niobium and W display similar and
353
pronounced variations (Figure 10). Zinc concentration shows considerable fluctuation (Figure 10).
354
Tin generally shows a slightly preferential enrichment in less dense huminites (Figure 9). It seems
355
that Tl does not vary much across DGC fractions (Figure 9).
356
In the S3 seam at Lincang, Ge is considered to have primarily an organic affinity.2 Its
357
preferential enrichment in denser fractions could result from the availability of more bonding sites
358
for Ge in denser huminite macerals. Uranium in U-bearing coal deposits is generally organically
359
bound, but it also occurs in U-bearing minerals.33,55-58 Beryllium and U in the Lincang S3 coal are
360
considered to have organic affinities,2 and this is also supported by positive Ge-Be and Ge-U
361
correlations (Figure 12D,E) in the present study; however, lower concentrations of Be and U in
362
DGC fractions (Table 5 and Figure 9) relative to those in the micronized coals (Be-180 µg/g,
363
U-160 µg/g; Table 3) suggest an inorganic affinity to some extent. Antimony has a mixed
364
organic-inorganic affinity,2 and the distinct positive Ge-Sb correlation indicates the preferential
365
association of Sb with organic matter (Figure 12C). Considering the larger particle sizes seen in
366
heavier fractions (Figure 5C), denser huminite macerals are more likely to contain minerals that
17
ACS Paragon Plus Environment
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
367
occur as inclusions in organic matter; therefore, the preferential enrichments of Be, U, and Sb in
368
heavier fractions (Figure 9) could result from more bonding sites in denser huminite macerals
369
and/or their inorganic affinities.
Page 18 of 51
370
Arsenic in the Lincang S3 coal has a mixed organic and inorganic (pyrite) affinity.2 For the
371
most part, it shows gradual variation across the density fractions (Figure 9) suggesting either an
372
organic affinity or that fine-grained pyrite remained in organic matter generally evenly distributed
373
across DGC fractions. The higher As concentration (558 µg/g; Table 3) in the micronized coal
374
relative to the DGC fractions (Table 5 and Figure 9) indicates that pyrite particles were mostly
375
separated from organic matter during the DGC process, and the negative Ge-As correlation
376
(Figure 12B) suggests that some pyrite still exists in the DGC fractions, which is consistent with
377
petrographic observations (Figure 5C,D).
378
Niobium in coal mainly occurs in oxide minerals,59 in organic association,60 or in association
379
with clay minerals.61,62 In the Lincang S3 coal, W is mostly organically associated and Nb has an
380
organic-inorganic mixed affinity,2 but neither are correlated with Ge in the DGC fractions (Figure
381
12A,F), suggesting inorganic affinities to some degree, which is also supported by their
382
pronounced variations across the density profile (Figure 10). In addition, very similar trends
383
(Figure 10) and a significant positive W-Nb correlation (Figure 12G) suggest similar controls on
384
their distribution. Thorium shows a similar density trend to W and Nb (Figure 10) and there is a
385
positive W-Th correlation (Figure 12H), suggesting similar controls on its distribution.
386 387
Tin, Tl, and Bi show very similar trends (Figure 9) and display positive correlations (Figure 12I,J), suggesting similar controls. Tl is thought to be associated with pyrite due to its high
18
ACS Paragon Plus Environment
Page 19 of 51
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
Energy & Fuels
388
correlation coefficient with pyritic sulfur,2 thus, Sn and Bi could also occur in pyrite in the
389
Lincang high-Ge coal. The variation in Zn content is different from that of any other trace element
390
(Figure 10) and suggests an inorganic affinity.
391
In addition, compared to other fractions, Li, Sc, Sr, Cd, Ba, Ta, and Hf are significantly
392
elevated in the 1.5102 g/mL fraction, and Sc, Ni, Rb, Sr, and Ba spike in the 1.4846 g/mL fraction
393
(Figure 10), indicating that some of these elements could exist in mineral particles. Comparable
394
variation trends (Figure 10) and positive correlations (Figure 12K,L) suggest that Sc, Sr, and Ba in
395
the Lincang high-Ge coal share the same mode of occurrence.
396
4.3.3. Distribution of rare earth elements and yttrium (REY)
397
REY concentrations in the DGC fractions from micronized WLTG C6-2 and LC S3-6 are
398
shown in Table 7 and Table 8, respectively. The threefold geochemical classification for REY
399
(LREY – La, Ce, Pr, Nd, and Sm; MREY – Eu, Gd, Tb, Dy, and Y; HREY – Ho, Er, Tm, Yb, and
400
Lu) is used in the present study.63 Generally, HREY in coal have a higher organic affinity relative
401
to LREY.64-66 In other words, LREY are more likely to be associated with minerals, which have
402
been found in many coals, e.g., rhabdophane, florencite, carbonates, or fluorocarbonates.56
403
However, zircon in most cases is enriched in HREY.67 This observation also applies to the
404
Wulantuga and Lincang high-Ge coals. Compared to other fractions, the REY anomalies of the
405
fractions at 1.3692 g/mL, 1.4596 g/mL, 1.4266 g/mL, and maybe 1.5515 g/mL from WLTG C6-2
406
(Table 7 and Figure 13A) and the fractions at 1.4846 g/mL and 1.5102 g/mL from LC S3-6 (Table
407
8 and Figure 13B) are due to the influence of mineral matter. Specifically, REY anomalies are
408
mainly due to elevated LREY (WLTG C6-2 and LC S3-6) and, to a lesser extent, elevated MREY
19
ACS Paragon Plus Environment
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 20 of 51
409
and HREY (WLTG C6-2) (Figure 13A,B), and REY (especially LREY) in WLTG C6-2 and LREY
410
in LC S3-6 could occur in minerals with Sc, Sr, Ba, and some other trace elements.
411
Uneven distribution of REY-bearing mineral matter could cause differentiation of REY
412
patterns among DGC fractions. Compared to Upper Continental Crust (UCC),68 three REY
413
enrichment patterns can be identified as L-type (LaN/LuN > 1), M-type (LaN/SmN < 1, GdN/LuN >
414
1), and H-type (LaN/LuN < 1).63 Most DGC fractions from WLTG C6-2 show an L/M-type
415
distribution pattern, whereas the fraction at 1.3692 g/mL is characterized by an M/H-type plot
416
(Table 7 and Figure 14A), which is most enriched in REY among all fractions due to mineral
417
inclusions. LREY in the fraction at 1.3692 g/mL have greater increases relative to HREY due to
418
the influence of minerals (Figure 13A), but HREY increase more when normalized to UCC
419
resulting in the M/H-type REY plot (Figure 14A). The REY distribution patterns do not
420
differentiate among the DGC fractions from LC S3-6, and all fractions are clearly characterized by
421
an H-type REY plot (Table 8 and Figure 14B), although some fractions are more enriched in
422
LREY (Figure 13B).
423
5. CONCLUSIONS
424
WLTG C6-2 and LC S3-6 were chosen as representative bench coals to characterize the trace
425
element distributions in DGC fractions (maceral concentrates) from the micronized Wulantuga
426
and Lincang high-Ge coals. Most of the trace elements, including Ge, W, As, and Sb in the
427
Wulantuga coal and Ge, W, As, Sb, Be, U, Nb, and REY in the Lincang coal, that are widely
428
considered to have varying degrees of organic affinity drastically decrease after HCl-HF
20
ACS Paragon Plus Environment
Page 21 of 51
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
Energy & Fuels
429
demineralization suggesting their acid-susceptible modes of occurrence (weakly bonded to organic
430
matter).
431
In the Wulantuga coal, Be and As are preferentially enriched in inertinite probably due to the
432
presence of more minerals in the heavier fractions. More bonding sites result in higher Ge contents
433
in huminite relative to inertinite. Antimony is slightly more enriched in huminite. A positive Ge-W
434
correlation and highly variable W concentrations vs. density suggest a mixed organic-inorganic
435
affinity for W, and Nb shares a similar mode of occurrence with W. Barium is mainly associated
436
with minerals. In the Lincang S3 coal, Ge content increases with density resulting from more
437
bonding sites in denser huminites. Beryllium, U, and Sb show preferential enrichments in the
438
heavier fractions due to the presence of more bonding sites in denser huminites and/or their
439
inorganic affinities. Arsenic concentration generally varies smoothly with density. Tungsten, Nb,
440
and possibly Th co-exist due to their comparable variation trends. For both of the Wulantuga and
441
Lincang coals, REY anomalies in some fractions result from elevated LREY. REY (especially
442
LREY) in WLTG C6-2 and LREY in LC S3-6 could occur in minerals with some trace elements,
443
including Sc, Sr, and Ba.
444
ACKNOWLEDGEMENTS
445
This research was supported by the National Natural Science Foundation of China (No.
446
41420104001), the National Key Basic Research Program of China (No. 2014CB238902), the
447
“111” Project (No. B17042), and the GSA Energy Geology Division A.L. Medlin Scholarship
448
(2016). William Huggett of the Department of Geology at Southern Illinois University Carbondale
449
is thanked for his help in preparing the micronized samples and for guidance in the DGC
21
ACS Paragon Plus Environment
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 22 of 51
450
procedures. Siyu Zhang, Xiaoyun Yan, Zhen Wang, and Lei Wang of China University of Mining
451
and Technology (Beijing) are thanked for performing the ICP-MS analyses.
452
REFERENCES
453
(1) Dai, S.; Wang, X.; Seredin, V. V.; Hower, J. C.; Ward, C. R.; O'Keefe, J. M. K.; Huang, W.; Li, T.; Li, X.; Liu,
454
H.; Xue, W.; Zhao, L. Petrology, mineralogy, and geochemistry of the Ge-rich coal from the Wulantuga Ge ore
455
deposit, Inner Mongolia, China: New data and genetic implications. Int. J. Coal Geol. 2012, 90-91, 72-99.
456
(2) Dai, S.; Wang, P.; Ward, C. R.; Tang, Y.; Song, X.; Jiang, J.; Hower, J. C.; Li, T.; Seredin, V. V.; Wagner, N.
457
J.; Jiang, Y.; Wang, X.; Liu, J. Elemental and mineralogical anomalies in the coal-hosted Ge ore deposit of
458
Lincang, Yunnan, southwestern China: Key role of N2-CO2-mixed hydrothermal solutions. Int. J. Coal Geol. 2015,
459
152, 19-46.
460 461 462
(3) Li, J.; Zhuang, X.; Querol, X. Trace element affinities in two high-Ge coals from China. Fuel 2011, 90, 240-247. (4) Zhuang, X.; Querol, X.; Alastuey, A.; Juan, R.; Plana, F.; Lopez-Soler, A.; Du, G.; Martynov, V. V.
463
Geochemistry and mineralogy of the Cretaceous Wulantuga high-germanium coal deposit in Shengli coalfield,
464
Inner Mongolia, northeastern China. Int. J. Coal Geol. 2006, 66, 119-136.
465
(5) Qi, H.; Hu, R.; Zhang, Q. Concentration and distribution of trace elements in lignite from the Shengli
466
coalfield, Inner Mongolia, China: implications on origin of the associated Wulantuga germanium deposit. Int. J.
467
Coal Geol. 2007, 71, 129-152.
468
(6) Du, G.; Zhuang, X.; Querol, X.; Izquierdo, M.; Alastuey, A.; Moreno, T.; Font, O. Ge distribution in the
469
Wulantuga high-germanium coal deposit in the Shengli coalfield, Inner Mongolia, northeastern China. Int. J. Coal
470
Geol. 2009, 78, 16-26.
471 472 473 474 475 476 477
(7) Zhang, S.; Wang, S.; Yin, J. The study of germanium ore in uranium-bearing coal of the Bangmai Basin, Lincang Region, Yunnan province. Uranium Geol. 1987, 3, 267-275 (in Chinese with an English abstract). (8) Zhang, S.; Yin, J.; Wang, S. Study on existent forms of germanium in coal, Bangmai Basin, Yunnan. Acta Sedimentol. Sin. 1987, 6, 29-41 (in Chinese with an English abstract). (9) Zhuang, H.; Lu, J.; Fu, J.; Liu, J. Elemental geochemistry and the organic/inorganic affinity of metallic elements in Lincang super-large germanium deposit. Prog. Nat. Sci. 1998, 8, 319-325 (in Chinese). (10) Etschmann, B.; Liu, W.; Li, K.; Dai, S.; Reith, F.; Falconer, D.; Kerr, G.; Paterson, D.; Howard, D.; Kappen,
478
P.; Wykes, J.; Brugger, J. Enrichment of germanium and associated arsenic and tungsten in coal and roll-front
479
uranium deposits. Chem. Geol. 2017, 463, 29-49.
22
ACS Paragon Plus Environment
Page 23 of 51
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
Energy & Fuels
480 481
(11) Zhuang, H.; Lu, J.; Fu, J.; Liu, J.; Ren, C.; Zou, D. Germanium occurrence in Lincang superlarge deposit in Yunnan, China. Sci. China D 1998, 41, 21-27 (suppl.).
482
(12) Du, G.; Xia, B.; Qin, S.; Tang, D.; Huang, W.; Wan, H. Genetic relationship of Ge-coal deposit in Shengli
483
coalfield and micro-environment of coal-forming swamp. J. China Coal Soc. 2008, 33, 405-409 (in Chinese with
484
an English abstract).
485 486 487 488
(13) Wei, Q.; Rimmer, S. M. Acid solubility and affinities of trace elements in the high-Ge coals from Wulantuga (Inner Mongolia) and Lincang (Yunnan Province), China. Int. J. Coal Geol. 2017, 178, 39-55. (14) Ward, C. R. Analysis, origin and significance of mineral matter in coal: An updated review. Int. J. Coal Geol. 2016, 165, 1-27.
489
(15) Dyrkacz, G. R.; Horwitz, E. P. Separation of coal macerals. Fuel 1982, 61, 3-12.
490
(16) Crelling, J. C.; Thomas, K. M.; Marsh, H. The release of nitrogen and sulphur during the combustion of
491 492 493
chars derived from lithotypes and maceral concentrates. Fuel 1993, 72, 349-357. (17) Rimmer, S. M.; Rowe, H. D.; Taulbee, D. N.; Hower, J. C. Influence of maceral content on δ13C and δ15N in a Middle Pennsylvanian coal. Chem. Geol. 2006, 225, 77-90.
494
(18) Rahman, M. W.; Rimmer, S. M.; Rowe, H. D.; Huggett, W. W. Carbon isotope analysis of whole-coal and
495
vitrinite from intruded coals from the Illinois Basin: No isotopic evidence for thermogenic methane. Chem. Geol.
496
2017, 453, 1-11.
497 498 499 500 501 502 503 504
(19) Hower, J. C.; Taulbee, D. N.; Rimmer, S. M.; Morrell, L. G. Petrographic and geochemical anatomy of lithotypes from the blue gem coal bed, southeastern Kentucky. Energy Fuels 1994, 8, 719-728. (20) Cui, X.; Li, J. Late Mesozoic basin types and their coal accumulation characteristics of Erlian basins in Inner Mongolia. Geosci. 1993, 7, 479-484 (in Chinese with an English abstract). (21) Hu, R.; Qi, H.; Bi, X.; Su, W.; Peng, J. Geology and geochemistry of the Lincang superlarge Germanium deposit hosted in coal seams, Yunnan, China. Geochim. Cosmochim. Acta 2006, 70, A269 (Suppl.). (22) Alvarez, R.; Clemente, C.; Gómez-Limón, D. The influence of nitric acid oxidation of low rank coal and its impact on coal structure. Fuel 2003, 82, 2007-2015.
505
(23) Strydom, C. A.; Bunt, J. R.; Schobert, H. H.; Raghoo, M. Changes to the organic functional groups of an
506
inertinite rich medium rank bituminous coal during acid treatment processes. Fuel Process. Technol. 2011, 92,
507
764-770.
508 509
(24) Pontolillo, J.; Stanton, R. W. Coal petrographic laboratory procedures and safety manual, II; U.S. Geological Survey Open-File Report, 1994; pp 94-631.
510
(25) Dai, S.; Wang, X.; Zhou, Y.; Hower, J. C.; Li, D.; Chen, W.; Zhu, X. Chemical and mineralogical
511
compositions of silicic, mafic, and alkali tonsteins in the late Permian coals from the Songzao Coalfield,
512
Chongqing, Southwest China. Chem. Geol. 2011, 282, 29-44.
23
ACS Paragon Plus Environment
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
513
(26) Li, X.; Dai, S.; Zhang, W.; Li, T.; Zheng, X.; Chen,W. Determination of As and Se in coal and coal
514
combustion products using closed vessel microwave digestion and collision/reaction cell technology (CCT) of
515
inductively coupled plasma mass spectrometry (ICP-MS). Int. J. Coal Geol. 2014, 124, 1-4.
516 517 518 519 520 521
Page 24 of 51
(27) Poe, S. H.; Taulbee, D. N.; Keogh, R. A. Density gradient centrifugation of -100 mesh coal: An alternative to using micronized samples for maceral separation. Org. Geochem. 1989, 14, 307-313. (28) Ketris, M. P.; Yudovich, Ya. E. Estimations of Clarkes for Carbonaceous biolithes: World average for trace element contents in black shales and coals. Int. J. Coal Geol. 2009, 78, 135-148. (29) Dai, S.; Graham, I. T.; Ward, C. R. A review of anomalous rare earth elements and yttrium in coal. Int. J. Coal Geol. 2016, 159, 82-95.
522
(30) Eskenazy, G. M. Geochemistry of beryllium in Bulgarian coals. Int. J. Coal Geol. 2006, 66, 305-315.
523
(31) Kolker, A.; Finkelman, R. B. Potentially hazardous elements in coal: modes of occurrence and summary of
524 525 526 527 528 529
concentration data for coal components. Coal Prep. 1998, 19, 133-157. (32) Seredin, V. V.; Danilcheva, Yu. A.; Magazina, L. O.; Sharova, I. G. Ge-bearing coals of the Luzanovka Graben, Pavlovka brown coal deposit, Southern Primorye. Lithol. Miner. Resour. 2006, 41, 280-301. (33) Seredin, V. V.; Finkelman, R. B. Metalliferous coals: a review of the main genetic and geochemical types. Int. J. Coal Geol. 2008, 76, 253-289. (34) Hu, R.; Qi, H.; Zhou, M.; Su, W.; Bi, X.; Peng, J.; Zhong, H. Geological and geochemical constraints on the
530
origin of the giant Lincang coal seam-hosted germanium deposit, Yunnan, SW China: a review. Ore Geol. Rev.
531
2009, 36, 221-234.
532
(35) Swaine, D. J. Trace Elements in Coal; Butterworths: London, 1990; pp 278.
533
(36) Dai, S.; Zeng, R.; Sun, Y. Enrichment of arsenic, antimony, mercury, and thallium in a late Permian
534 535
anthracite from Xingren, Guizhou, southwest China. Int. J. Coal Geol. 2006, 66, 217-226. (37) Finkelman, R. B. Modes of occurrence of environmentally sensitive trace elements in coal. In Environmental
536
Aspects of Trace Elements in Coal; Swaine, D. J., Goodarzi, F., Eds.; Kluwer Academic Publishing: Dordrecht,
537
1995; pp 24-50.
538
(38) Minkin, J. A.; Finkelman, R. B.; Thompson, C. L.; Chao, E. C. T.; Ruppert, L. F.; Blank, H.; Cecil, C. B.
539
Microcharacterization of arsenic- and selenium-bearing pyrite in Upper Freeport coal, Indiana County,
540
Pennsylvania. Scan. Electron Microsc. 1984, 4, 1515-1524.
541
(39) Coleman, S. L.; Bragg, L. J. Distribution and mode of occurrence of arsenic in coal. In Recent Advances in
542
Coal Geochemistry; Chyi, L. L., Chou, C.-L., Eds.; Special Paper of the Geological Society of America, 1990; vol
543
248, pp 13-26.
544 545
(40) Ruppert, L. F.; Minkin, J. A.; McGee, J. J.; Cecil, C. B. An unusual occurrence of arsenic-bearing pyrite in the Upper Freeport coal bed, west-central Pennsylvania. Energy Fuels 1992, 6, 120-125.
24
ACS Paragon Plus Environment
Page 25 of 51
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
Energy & Fuels
546 547 548 549
(41) Eskenazy, G. M. Geochemistry of arsenic and antimony in Bulgarian coals. Chem. Geol. 1995, 119, 239-254. (42) Hower, J. C.; Robertson, J. D.; Wong, A. S.; Eble, C. F.; Ruppert, L. F. Arsenic and lead concentrations in the Pond Creek and Fire Clay coal beds, Eastern Kentucky coal field. Appl. Geochem. 1997, 12, 281-289.
550
(43) Ward, C. R. Mineralogical analysis in hazard assessment. In Geological Hazards-The Impact to Mining;
551
Doyle, R., Moloney, J., Eds.; Coalfield Geology Council of New South Wales: Newcastle, Australia, 2001; pp
552
81-88.
553
(44) Yudovich, Ya. E.; Ketris, M. P. Arsenic in coal: a review. Int. J. Coal Geol. 2005, 61, 141-196.
554
(45) Hower, J. C.; Eble, C. F.; Quick, J. C. Mercury in Eastern Kentucky coals: geologic aspects and possible
555 556 557 558
reduction strategies. Int. J. Coal Geol. 2005, 62, 223-236. (46) Hower, J. C.; Ruppert, L. F.; Eble, C. F.; Clark, W. L. Geochemistry, petrology, and palynology of the Pond Creek coal bed, northern Pike and southern Martin counties, Kentucky. Int. J. Coal Geol. 2005, 62, 167-181. (47) Ding, Z.; Zheng, B.; Zhang, J.; Long, J.; Belkin, H. E.; Finkelman, R. B.; Zhao, F.; Chen, C.; Zhou, D.; Zhou,
559
Y. Geological and geochemical characteristics of high arsenic coals from endemic arsenosis areas in southwestern
560
Guizhou Province, China. Appl. Geochem. 2001, 16, 1353-1360.
561
(48) Belkin, H. E.; Zheng, B. S.; Zhou, D. X. Preliminary results on the geochemistry and mineralogy of arsenic
562
in mineralized coals from endemic arsenosis area in Guizhou Province. 14th Annual International Pittsburgh Coal
563
Conference and Workshop Proceedings; Taiyuan, Shanxi, China, Spet, 23-27, 1997; pp 1-20 (CD-ROM).
564 565
(49) Zhao, F.; Ren, D.; Zheng, B.; Hu, T.; Liu, T. Modes of occurrence of arsenic in higharsenic coal by extended X-ray absorption fine structure spectroscopy. Chin. Sci. Bull. 1998, 43, 1660-1663.
566
(50) Eskenazy, G. M. The geochemistry of tungsten in Bulgarian coals. Int. J. Coal Geol. 1982, 2, 99-111.
567
(51) Dai, S.; Ren, D.; Tang, Y.; Yue, M.; Hao, L. Concentration and distribution of elements in Late Permian
568 569 570 571 572 573
coals from western Guizhou Province, China. Int. J. Coal Geol. 2005, 61, 119-137. (52) Spears, D. A.; Borrego, A.; Cox, A.; Martinez-Tarazona, R. Use of laser ablation ICP-MS to determine trace element distributions in coals, with special reference to V, Ge and Al. Int. J. Coal Geol. 2007, 72, 165-176. (53) Gürdal, G. Geochemistry of trace elements in Çan coal (Miocene), Çanakkale, Turkey. Int. J. Coal Geol. 2008, 74, 28-40. (54) Sia, S. G.; Abdullah, W. H. Concentration and association of minor and trace elements in Mukah coal from
574
Sarawak, Malaysia, with emphasis on the potentially hazardous trace elements. Int. J. Coal Geol. 2011, 88,
575
179-193.
576
(55) Dai, S.; Song, W.; Zhao, L.; Li, X.; Hower, J. C.; Ward, C. R.; Wang, P.; Li, T.; Zheng, X.; Seredin, V. V.;
577
Xie, P.; Li, Q. Determination of boron in coal using closed vessel microwave digestion and inductively coupled
578
plasma mass spectrometry (ICP-MS). Energy Fuels 2014, 28, 4517-4522.
25
ACS Paragon Plus Environment
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 26 of 51
579
(56) Dai, S.; Xie, P.; Jia, S.; Ward, C. R.; Hower, J. C.; Yan, X.; French, D. Enrichment of U-Re-V-Cr-Se and
580
rare earth elements in the Late Permian coals of the Moxinpo Coalfield, Chongqing, China: Genetic implications
581
from geochemical and mineralogical data. Ore Geol. Rev. 2017, 80, 1-17.
582
(57) Hower, J. C.; Eble, C. F.; O’Keefe, J. M. K.; Dai, S.; Wang, P.; Xie, P.; Liu, J.; Ward, C. R.; French, D.
583
Petrology, Palynology, and Geochemistry of Gray Hawk Coal (Early Pennsylvanian, Langsettian) in Eastern
584
Kentucky, USA. Minerals 2015, 5, 592-622.
585 586 587 588 589 590 591
(58) Liu, J.; Yang, Z.; Yan, X.; Ji, D.; Yang, Y.; Hu, L. Modes of occurrence of highly-elevated trace elements in superhigh-organic-sulfur coals. Fuel 2015, 156, 190-197. (59) Finkelman, R. B. Trace and minor elements in coal. In Organic Geochemistry; Engel, M. H., Masko, S. A., Eds.; Plenum Press: New York, 1993; pp 593-607. (60) Seredin, V. V. The first data on abnormal niobium content in Russian coals. Dokl. Russ. Akad. Nauk 1994, 335, 634-636. (61) Dai, S.; Luo, Y.; Seredin, V. V.; Ward, C. R.; Hower, J. C.; Zhao, L.; Liu, S.; Tian, H.; Zou, J. Revisiting the
592
late Permian coal from the Huayingshan, Sichuan, southwestern China: Enrichment and occurrence modes of
593
minerals and trace elements. Int. J. Coal Geol. 2014, 122, 110-128.
594
(62) Zhao, L.; Dai, S.; Graham, I. T.; Li, X.; Liu, H.; Song, X.; Hower, J. C.; Zhou, Y. Cryptic sediment-hosted
595
critical element mineralization from eastern Yunnan Province, southwestern China: Mineralogy, geochemistry,
596
relationship to Emeishan alkaline magmatism and possible origin. Ore Geol. Rev. 2017, 80, 116-140.
597 598 599 600 601 602 603
(63) Seredin, V. V.; Dai, S. Coal deposits as potential alternative sources for lanthanides and yttrium. Int. J. Coal Geol. 2012, 94, 67-93. (64) Eskenazy, G. M. Rare earth elements and yttrium in lithotypes of Bulgarian coals. Org. Geochem. 1987, 11, 83-89. (65) Eskenazy, G. M. Rare earth elements in a sampled coal from the Pirin Deposit, Bulgaria. Int. J. Coal Geol. 1987, 7, 301-314. (66) Dai, S.; Zhang, W.; Ward, C. R.; Seredin, V. V.; Hower, J. C.; Li, X.; Song, W.; Wang, X.; Kang, H.; Zheng,
604
L.; Wang, P.; Zhou, D. Mineralogical and geochemical anomalies of late Permian coals from the Fusui Coalfield,
605
Guangxi Province, southern China: Influences of terrigenous materials and hydrothermal fluids. Int. J. Coal Geol.
606
2013, 105, 60-84.
607 608 609 610
(67) Dai, S.; Finkelman, R. B. Coal as a promising source of critical elements: Progress and future prospects. Int. J. Coal Geol. 2017, https://doi.org/10.1016/j.coal.2017.06.005. (68) Taylor, S. R.; McLennan, S. M. The continental crust: its composition and evolution; Blackwell: Oxford, 1985; pp 312.
611
26
ACS Paragon Plus Environment
Page 27 of 51
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
Energy & Fuels
612
Figure Captions
613
Figure 1. Relationship between maceral content (A. Huminite; B. Inertinite) and Ge concentrations from 13 bench
614
samples of the No. 6 coal seam, Wulantuga. Original data from Dai et al..1 Note that the two outliers could be
615
influencing the correlation coefficient.
616 617
Figure 2. Location (A) and geological settings of the Wulantuga (B; modified after Du et al.6) and Lincang (C;
618
modified after Hu et al.34) Ge ore deposits.
619 620
Figure 3. Photomicrographs of the Wulantuga and Lincang high-Ge coals before and after micronization. (A)
621
WLTG C6-2, minus 20-mesh coal; (B) WLTG C6-2, micronized coal; (C) LC S3-6, minus 20-mesh coal; (D) LC
622
S3-6, micronized coal.
623 624
Figure 4. Minus 200-mesh coals showing coal fragments containing a mix of macerals and minerals. (A, B)
625
WLTG C6-2; (C, D) LC S3-6.
626 627
Figure 5. DGC profiles of micronized and micronized-demineralized coal samples (WLTG C6-2 and LC S3-6).
628
Photomicrographs show petrographic composition of selected fractions. (A) micronized WLTG C6-2; (B)
629
micronized-demineralized WLTG C6-2; (C) micronized LC S3-6; (D) micronized-demineralized LC S3-6. Scale
630
bar on photomicrographs is 20 microns, and fraction density (g/mL) is at the bottom-left of each photomicrograph.
631
Some fine-grained pyrite can still be observed in the DGC fractions.
632 633
Figure 6. Comparison of the concentrations of selected trace elements and REY before and after demineralization
634
in WLTG C6-2 and LC S3-6. Micro, micronized coal; Demin, micronized-demineralized coal.
635 636
Figure 7. Distribution of trace elements (Group 1) in DGC fractions of micronized WLTG C6-2 (µg/g). The
637
vertical red line represents the boundary between huminite-rich (H) and inertinite-rich (I) density fractions.
638 639
Figure 8. Distribution of trace elements (Group 2) in DGC fractions of micronized WLTG C6-2 (µg/g). The
640
vertical red line represents the boundary between huminite-rich (H) and inertinite-rich (I) density fractions; orange
641
dots indicate concentrations below detection limits that are regarded as 0.
642 643
Figure 9. Distribution of trace elements (Group 1) in DGC fractions of micronized LC S3-6 (µg/g). The vertical
644
pink line represents the peak density of huminite.
645 646
Figure 10. Distribution of trace elements (Group 2) in DGC fractions of micronized LC S3-6 (µg/g). The vertical
647
pink line represents the peak density of huminite; orange dots indicate concentrations below detection limits that
648
are regarded as 0.
27
ACS Paragon Plus Environment
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 28 of 51
649 650
Figure 11. Relationships between selected trace elements in DGC fractions from micronized WLTG C6-2.
651 652
Figure 12. Relations between selected trace elements in DGC fractions from micronized LC S3-6.
653 654
Figure 13. REY distribution by density in the DGC fractions from micronized WLTG C6-2 (A) and LC S3-6 (B).
655
The vertical red lines represent the density boundary between huminite and inertinite from WLTG C6-2 (A), and
656
the vertical pink line represents the peak density of huminite in LC S3-6 (B).
657 658
Figure 14. REY distribution patterns for DGC fractions from micronized WLTG C6-2 (A) and LC S3-6 (B). REY
659
plots are normalized to Upper Continental Crust (UCC).68
660
28
ACS Paragon Plus Environment
Page 29 of 51
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
Energy & Fuels
661
Table 1. Maceral Compositions of WLTG C6-2 and LC S3-6 (vol. %; Mineral-free Basis) Sample
Tex
Ulm
Att
Den
Corp
Gel
Fus
Sf
Ma
Fun
Inert
Res
Cut
Total
T-Hum
T-Inert
T-Lip
WLTG C6-2
2.0
25.1
11.0
16.9
1.2
2.2
23.1
6.6
0.6
1.0
9.4
0.6
0.2
99.9
58.4
40.7
0.8
LC S3-6
4.6
30.7
3.0
46.0
0.8
13.6
0
0
0
1.3
0
0
0
100
98.7
1.3
0
662 663 664
Tex, textinite; Ulm, ulminite; Att, attrinite; Den, densinite; Corp, corpohuminite; Gel, gelinite; T-Hum, total huminite; Fus, fusinite, Sf, semifusinite; Mac,
665 666
Table 2. Average Density (g/mL) and Normalized Weight (g) for DGC Fractions from Micronized and
macrinite; Fun, funginite; Inert, inertodetrinite; T-Inert, total inertinite; Res, resinite; Cut, cutinite; T-Lip, total liptinite.
Micronized-demineralized Coal Samples (WLTG C6-2 and LC S3-6) Micro WLTG C6-2
Demin WLTG C6-2
Micro LC S3-6
Demin LC S3-6
Density
Norm. Wt.
Density
Norm. Wt.
Density
Norm. Wt.
Density
Norm. Wt.
1.5598
0.0917
1.5912
0.0186
1.5189
0.1113
1.4864
0.0029
1.5572
0.1081
1.5817
0.0183
1.5143
0.1568
1.4768
0.0056
1.5515
0.1499
1.5732
0.0265
1.5102
0.2128
1.4661
0.0084
1.5426
0.2035
1.5649
0.0352
1.5069
0.2746
1.4554
0.0225
1.5333
0.2820
1.5533
0.0450
1.5009
0.4167
1.4448
0.0770
1.5220
0.3808
1.5382
0.0847
1.4932
0.5812
1.4319
0.1761
1.5106
0.4883
1.5174
0.1655
1.4846
0.7851
1.4172
0.3224
1.4985
0.5765
1.4952
0.2698
1.4742
0.9663
1.4021
0.4839
1.4871
0.6375
1.4699
0.4728
1.4638
1.0000
1.3844
0.7134
1.4742
0.7289
1.4453
0.7299
1.4523
0.9602
1.3660
0.9531
1.4596
0.8190
1.4187
0.8046
1.4412
0.8916
1.3471
1.0000
1.4443
0.8512
1.3912
0.9686
1.4305
0.8822
1.3284
0.6417
1.4266
1.0000
1.3642
1.0000
1.4175
0.8534
1.3096
0.2631
1.4074
0.4560
1.3382
0.3389
1.4026
0.7587
1.2907
0.0979
1.3879
0.2349
1.3132
0.0910
1.3864
0.5841
1.2717
0.0469
1.3692
0.1390
1.2887
0.0380
1.3693
0.3574
1.2527
0.0271
1.3513
0.0847
1.2647
0.0248
1.3529
0.1998
1.2338
0.0190
1.3306
0.0545
1.2411
0.0204
1.3353
0.1028
1.2139
0.0132
667 668 669
Micro, micronized coal; Demin, micronized-demineralized coal; Norm. Wt., normalized fraction weight. The weight of each
670 671
Table 3. Trace Element Concentrations (µg/g) for Micronized and Micronized-demineralized Coal Samples (WLTG C6-2
fraction was normalized to the fraction containing the most material.
and LC S3-6), Along with Concentration Coefficients (CC) and Reduction Rates (RR) WLTG C6-2
LC S3-6
Elements Li
a
b
Micro
Demin
CC
RR
Micro
Demin
CCa
RRb
4.01
bdl
0.40
100e
10.2
bdl
1.02
100e
Worldc 10
Be
11.3
1.50
9.42
87
180
1.73
150
99
1.2
Sc
0.82
0.21
0.20
74
5.00
0.20
1.22
96
4.1
V
3.94
bdl
0.18
100e
4.50
bdl
0.20
100e
22
Cr
10.9
5.58
0.73
49
11.7
5.25
0.78
55
15
Co
0.72
0.24
0.17
67
2.95
0.19
0.70
94
4.2
Ni
7.67
3.48
0.85
55
14.9
2.86
1.66
81
9
Cu
5.92
1.94
0.39
67
13.6
4.41
0.91
68
15
29
ACS Paragon Plus Environment
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
3.95
0.04
ndf
119
Page 30 of 51
Zn
0.77
20.7
6.61
83
18
Ga
1.24
0.56
0.23
55
8.42
0.47
1.53
94
5.5
Ge
188
9.76
94.0
95
1490
64.7
745
96
2
As
887
36.2
117
96
558
187
73.4
66
d
f
7.6 e
Se
bdl
bdl
nd
nd
0.17
bdl
0.17
100
Rb
4.52
bdl
0.45
100e
32.4
6.67
3.24
79
10
1
Sr
149
8.84
1.24
94
27.4
1.95
0.23
93
120
Zr
7.28
3.80
0.21
48
7.96
1.84
0.23
77
35
Nb
0.58
0.23
0.18
60
25.2
4.63
7.64
82
3.3
Mo
1.48
0.46
0.67
69
7.33
4.22
3.33
42
2.2
0.101
0.012
1.12
88
0.09
1.615
0.178
6.73
89
Ag
0.071
bdl
0.79
100
Cd
0.021
0.004
0.09
81
In
bdl
d
bdl
nd
e
f
nd
0.01
bdl
0.48
100 f
0.24 e
0.021
Sn
2.72
0.05
3.44
98
4.80
6.00
6.08
nd
0.79
Sb
46.0
22.0
54.8
52
34.5
22.8
41.1
34
0.84
Cs
5.04
2.00
5.14
60
17.8
6.36
18.2
64
0.98
Ba
2826
1011
18.8
64
56.3
10.2
0.38
82
150
Hf
0.32
0.11
0.27
66
0.21
0.11
0.18
48
1.2
Ta
0.07
0.01
0.27
86
0.81
0.74
3.12
9
0.26
W
159
14.2
133
91
403
102
336
75
1.2
Tl
2.14
0.08
3.15
96
9.17
2.95
13.5
68
0.68
Pb
4.04
bdl
0.61 d
e
25.9
0.55
3.92
98
6.6
f
100
Bi
bdl
bdl
nd
nd
1.70
0.26
2.02
85
0.84
Th
0.74
0.07
0.22
91
4.78
0.36
1.45
92
3.3
U
0.29
0.20
0.10
31
160
1.92
55.2
99
2.9
La
3.62
1.00
0.36
72
2.54
0.41
0.25
84
10
Ce
6.13
1.69
0.28
72
6.50
0.87
0.30
87
22
Pr
0.74
0.24
0.21
68
0.89
0.10
0.25
89
3.5
Nd
3.03
0.94
0.28
69
3.76
0.39
0.34
90
11
Sm
0.62
0.20
0.33
68
1.27
0.16
0.67
87
1.9
Eu
2.50
0.91
5.00
64
0.21
0.03
0.42
86
0.5
Gd
1.01
0.32
0.39
68
1.42
0.20
0.55
86
2.6
Tb
0.13
0.05
0.41
62
0.55
0.07
1.72
87
0.32
Dy
0.51
0.21
0.26
59
3.80
0.50
1.90
87
2
Y
2.51
1.00
0.29
60
17.96
2.84
2.09
84
8.6
Ho
0.10
0.04
0.20
60
0.78
0.10
1.56
87
0.5
Er
0.24
0.11
0.28
54
2.62
0.28
3.08
89
0.85
Tm
0.04
0.01
0.13
75
0.46
0.06
1.48
87
0.31
Yb
0.20
0.09
0.20
55
3.50
0.42
3.50
88
1
Lu
0.03
0.01
0.16
67
0.54
0.05
2.84
91
0.19
REY
21.40
6.83
0.33
68
46.80
6.46
0.72
86
65.27
LREYg
14.14
4.07
0.29
71
14.96
1.94
0.31
87
48.4
MREYg
6.66
2.49
0.48
63
23.94
3.63
1.71
85
14.02
g
0.60
0.27
0.21
55
7.90
0.90
2.77
89
2.85
HREY
30
ACS Paragon Plus Environment
Page 31 of 51
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
Energy & Fuels
672 673 674 675 676 677 678 679 680 681
Micro, micronized coal; Demin, micronized-demineralized coal; bdl, below detection limit. REY=REE+Y. a
CC, concentration coefficient, ratio of concentrations of elements in Micro to world low-rank coals; bRR, reduction rate (%),
(concentration in Micro - concentration in Demin) / concentration in Micro * 100%; caverage concentrations of elements in world low-rank coals shown for comparison;28 dnd, no data due to bdl concentration in Micro; eRR is regarded as 100% due to the bdl concentration in Demin; fnd, no data due to bdl concentration in Micro or higher concentration in Demin than that in Micro; gas described by Seredin and Dai,63 the threefold geochemical classification for REY (LREY– La, Ce, Pr, Nd, and Sm; MREY – Eu, Gd, Tb, Dy, and Y; HREY – Ho, Er, Tm, Yb, and Lu) is used in the present study.
Table 4. Trace Element Concentrations (µg/g, Cs-free Basis) of DGC Fractions Obtained from Micronized WLTG C6-2 Coal Sample Densitya
1.5515
1.5426
1.5333
1.522
1.5106
1.4985
1.4871
1.4742
1.4596
1.4443
1.4266
1.4074
1.3879
1.3692
Li
0.71
0.63
0.50
0.45
0.27
0.28
0.22
0.20
0.58
0.19
0.18
0.29
0.41
3.21
Be
9.49
9.58
9.18
8.82
8.13
7.77
6.99
6.13
5.35
4.26
3.24
2.94
2.79
3.22
Sc
0.98
0.59
0.60
0.52
0.52
0.45
0.41
0.33
1.76
0.34
0.80
0.34
0.33
2.51
V
2.63
2.48
2.36
2.23
1.94
1.94
1.97
2.02
1.95
1.94
1.89
2.10
2.31
2.60
Cr
4.54
4.29
3.78
4.18
3.31
3.56
6.95
4.24
3.81
4.40
4.54
5.57
5.85
6.84
Co
0.34
0.32
0.31
0.28
0.24
0.23
0.26
0.24
0.28
0.27
0.30
0.36
0.41
0.73
Ni
3.10
2.98
2.75
2.52
2.09
2.22
4.78
2.40
2.43
2.49
2.60
2.99
3.10
3.58
Cu
8.39
7.45
6.91
6.13
5.67
5.51
5.81
5.97
6.09
6.81
7.46
8.93
10.2
10.2
Zn
3.19
2.64
2.80
2.24
1.41
1.24
1.28
1.47
1.06
1.23
2.39
1.83
95.4
125
Ga
1.03
0.94
0.86
0.80
0.71
0.71
0.71
0.69
0.84
0.79
0.85
0.98
1.10
1.47
Ge
123
122
122
130
129
140
153
169
189
204
196
195
169
139
As
nd
428
410
384
337
333
326
330
337
374
262
249
217
nd
Se
nd
0.28
0.16
0.20
0.03
0.12
bdl
0.04
bdl
bdl
bdl
0.05
bdl
nd
Rb
2.71
1.72
1.56
1.47
1.25
1.14
1.22
1.05
1.84
1.31
1.34
1.27
1.37
1.58
Sr
8.52
7.90
8.21
8.96
9.72
10.0
10.2
9.74
17.9
8.04
7.36
4.19
3.34
12.9
Zr
4.12
3.73
3.86
3.78
3.59
3.50
3.77
4.05
4.84
5.10
5.64
6.81
6.88
7.10
Nb
0.02
bdl
0.003
0.05
0.03
0.05
0.06
0.10
0.18
0.16
0.26
0.38
0.30
0.22
Mo
0.31
0.18
0.11
0.11
bdl
bdl
0.31
bdl
bdl
bdl
bdl
0.13
0.09
bdl
Ag
bdl
bdl
bdl
0.20
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
Cd
0.012
0.014
0.012
0.010
0.008
0.004
0.008
0.006
0.008
0.004
0.012
0.028
0.022
0.038
In
bdl
0.001
bdl
0.001
bdl
bdl
bdl
bdl
bdl
bdl
bdl
0.001
0.001
0.001
Sn
0.01
bdl
bdl
bdl
bdl
bdl
0.02
bdl
bdl
0.05
0.05
0.15
0.15
0.11
Sb
43.7
40.7
39.2
38.5
36.4
37.3
38.9
41.4
44.4
46.2
45.7
47.8
44.8
39.6
Ba
12.9
10.3
11.4
9.57
8.41
8.21
8.61
8.23
16.7
9.59
10.1
8.01
7.69
20.6
Hf
0.13
0.10
0.11
0.09
0.10
0.10
0.10
0.11
0.14
0.15
0.16
0.19
0.19
0.19
Ta
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
W
24.7
18.3
16.3
85.0
80.3
77.5
79.1
93.0
115
107
105
124
93.4
83.4
Tl
0.51
0.45
0.48
0.43
0.32
0.34
0.37
0.33
0.34
0.37
0.41
0.51
0.61
0.55
Pb
1.11
0.95
0.95
0.80
0.69
0.56
0.66
0.58
0.64
0.51
0.52
0.59
0.72
0.88
Bi
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
Th
0.51
0.51
0.39
0.42
0.41
0.32
0.31
0.32
1.01
0.34
0.59
0.55
0.50
0.57
U
0.19
0.19
0.16
0.15
0.14
0.13
0.12
0.13
0.18
0.14
0.17
0.18
0.19
0.21
31
ACS Paragon Plus Environment
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
682 683 684 685 686 687
Note: Compared to Cs value in the micronized WLTG C6-2 coal sample (5.04 µg/g; Table 3), Cs contents in DGC fractions are extremely high (up to > 25,000 µg/g) and cannot be used due to use of CsCl in DGC processing, thus trace element concentrations are given on a Cs-free basis. adensity reported as g/mL. bdl, below detection limit; nd, no data.
Table 5. Trace Element Concentrations (µg/g, Cs-free Basis) of DGC Fractions Obtained from Micronized LC S3-6 Coal Sample Densitya
688 689 690 691 692
Page 32 of 51
1.5102
1.5069
1.5009
1.4932
1.4846
1.4742
1.4638
1.4523
1.4412
1.4305
1.4175
1.4026
1.3864
1.3693
1.3529
Li
4.92
3.78
3.33
3.33
3.53
3.19
3.39
3.38
3.25
3.18
2.94
2.74
2.64
2.70
2.76
Be
76.5
78.6
82.0
83.5
78.1
75.7
77.6
73.4
71.9
69.5
66.7
61.4
56.8
51.8
50.8
Sc
4.27
3.27
3.32
3.38
4.34
2.97
2.85
2.73
2.57
2.53
2.18
2.05
1.87
1.85
1.98
V
3.18
3.17
2.96
3.11
3.04
2.95
3.01
3.02
2.98
2.94
2.82
2.74
2.68
2.61
2.56
Cr
4.24
3.77
3.57
3.74
4.56
3.78
3.55
4.56
4.12
4.35
3.54
4.75
4.32
3.98
3.64
Co
0.51
0.50
0.48
0.48
0.51
0.43
0.42
0.39
0.39
0.38
0.35
0.36
0.34
0.34
0.36
Ni
3.15
3.10
2.95
2.97
3.62
2.89
2.90
3.03
3.12
3.01
2.79
2.83
2.48
2.35
2.34
Cu
8.29
7.92
7.82
7.93
8.60
8.57
9.23
9.66
10.0
10.7
10.3
10.4
10.5
10.9
11.1
Zn
52.9
56.9
26.8
38.8
41.2
36.8
40.9
6.68
36.9
34.0
33.2
51.0
52.8
48.7
67.7
Ga
6.65
6.55
6.20
6.14
5.93
5.33
5.01
4.66
4.37
4.05
3.70
3.42
3.25
3.20
3.22
Ge
1761
1712
1693
1666
1587
1564
1519
1550
1524
1483
1421
1378
1289
1206
1037
As
nd
240
251
256
271
284
292
302
321
328
287
333
314
260
nd
Se
nd
bdl
0.30
0.42
0.46
0.44
0.43
0.41
0.41
0.36
0.44
0.44
0.75
bdl
nd
Rb
13.3
11.8
10.8
10.8
13.3
10.7
11.3
11.4
11.4
11.0
10.0
9.49
9.36
9.70
10.0
Sr
11.4
3.87
3.79
3.60
16.3
3.20
3.13
3.31
3.03
3.39
2.64
2.32
2.00
1.87
3.45
Zr
5.41
5.95
5.37
6.08
6.30
6.44
6.69
7.41
7.70
8.46
7.94
7.75
7.42
7.99
7.65
Nb
26.1
26.9
8.81
12.0
27.7
20.1
8.59
27.4
26.0
27.9
26.8
21.2
26.2
25.5
23.9
Mo
5.02
5.07
4.57
4.81
5.24
5.38
5.22
5.81
6.03
6.43
6.45
6.59
6.58
6.64
5.81
Ag
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
bdl
Cd
0.315
0.083
0.072
0.077
0.091
0.075
0.069
0.069
0.070
0.065
0.067
0.059
0.052
0.064
0.085
In
0.015
0.013
0.013
0.013
0.013
0.013
0.011
0.013
0.013
0.013
0.011
0.013
0.013
0.015
0.013
Sn
2.75
2.76
2.23
2.30
2.56
2.61
2.47
2.96
3.03
3.05
2.90
2.82
2.92
3.02
3.00
Sb
47.0
45.9
42.8
42.2
43.5
41.5
38.1
39.7
38.5
38.0
37.2
36.9
36.6
36.1
33.4
Ba
23.7
16.8
15.7
14.9
29.5
13.6
14.1
14.9
12.3
13.5
10.6
10.2
8.3
7.79
10.8
Hf
0.39
0.12
0.08
0.10
0.11
0.09
0.09
0.11
0.11
0.13
0.10
0.09
0.09
0.10
0.10
Ta
3.33
1.06
bdl
bdl
0.69
0.07
bdl
0.52
0.42
0.61
0.36
0.06
0.49
0.34
0.38
W
279
365
141
99.7
380
266
73.4
304
332
352
338
232
244
283
236
Tl
2.17
2.09
1.72
1.79
2.04
1.98
1.94
2.28
2.29
2.27
2.15
2.05
2.13
1.97
1.84
Pb
11.5
11.0
10.4
10.4
10.6
10.3
10.9
11.2
11.4
11.3
10.7
10.5
10.2
9.96
10.0
Bi
1.00
1.07
0.87
0.81
0.93
1.02
0.89
1.09
1.16
1.21
1.16
1.08
1.13
1.22
1.26
Th
1.77
1.47
1.17
1.01
2.62
1.71
1.09
1.83
1.95
1.93
1.84
1.73
1.78
1.99
2.07
U
65.9
66.0
70.6
73.4
71.1
70.7
70.2
68.5
66.3
56.2
55.0
59.6
56.7
54.1
51.8
Note: Compared to Cs value in the micronized LC S3-6 coal sample (17.8 µg/g; Table 3), Cs contents in DGC fractions are extremely high (up to > 7,000 µg/g) and cannot be used due to use of CsCl in DGC processing, thus trace element concentrations are given on a Cs-free basis. adensity reported as g/mL. bdl, below detection limit; nd, no data.
Table 6. Trace Elements Roughly Classified by the Smoothness Degree of Variation with Density
32
ACS Paragon Plus Environment
Page 33 of 51
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
Energy & Fuels
Group No.
Smoothness degree of variation
1
Smooth
2
693 694 695 696 697
Variable
Micro LC S3-6
Be, V, Co, Cu, Ga, Ge, As, Zr, Sb, Hf,
Be, V, Co, Cu, Ga, Ge, As, Zr, Mo,
Tl, Pb
Sn, Sb, Tl, Pb, Bi, U
Li, Sc, Cr, Ni, Zn, Se, Rb, Sr, Nb, Mo,
Li, Sc, Cr, Ni, Zn, Se, Rb, Sr, Nb, Cd,
Cd, Sn, Ba, W, Th, U
In, Ba, Ta, Hf, Th, W
Note: Cs is not included because CsCl was employed during the DGC procedure. Micro, micronized coal. Some trace elements are excluded here and their variations cannot be plotted properly in Figures 7-10, due to concentrations that are below detection limits in most DGC fractions, including Ag, In, Ta, and Bi in micronized WLTG C6-2 and Ag in micronized LC S3-6.
Table 7. REY Concentrations in DGC Fractions from Micronized WLTG C6-2 (µg/g, Cs-free Basis) Densitya
698 699 700 701
Micro WLTG C6-2
1.5515
1.5426
1.5333
1.522
1.5106
1.4985
1.4871
1.4742
1.4596
1.4443
1.4266
1.4074
1.3879
1.3692
La
2.11
1.62
1.58
1.56
1.67
1.51
1.48
1.27
3.37
1.14
1.97
1.00
1.11
3.04
Ce
3.60
2.98
2.91
2.94
2.87
2.80
2.69
2.38
5.64
2.07
3.01
1.83
2.05
8.15
Pr
0.50
0.36
0.38
0.36
0.36
0.33
0.32
0.27
0.82
0.23
0.44
0.22
0.23
0.89
Nd
2.06
1.55
1.60
1.54
1.56
1.39
1.38
1.11
3.31
0.99
1.74
0.88
0.94
3.84
Sm
0.44
0.32
0.33
0.32
0.34
0.27
0.27
0.22
0.67
0.18
0.35
0.16
0.18
0.90
Eu
0.09
0.05
0.07
0.05
0.06
0.05
0.04
0.03
0.14
0.03
0.07
0.02
0.02
0.20
Gd
0.47
0.33
0.38
0.35
0.34
0.31
0.28
0.25
0.68
0.18
0.35
0.16
0.17
0.98
Tb
0.06
0.04
0.04
0.04
0.04
0.03
0.03
0.02
0.08
0.01
0.04
0.01
0.01
0.15
Dy
0.36
0.26
0.33
0.28
0.25
0.22
0.20
0.17
0.55
0.13
0.27
0.11
0.13
1.02
Y
1.94
1.63
1.81
1.54
1.62
1.37
1.30
1.03
2.61
0.75
1.38
0.69
0.80
5.08
Ho
0.07
0.04
0.05
0.04
0.04
0.04
0.04
0.03
0.10
0.02
0.05
0.02
0.02
0.19
Er
0.18
0.14
0.16
0.13
0.15
0.12
0.12
0.09
0.30
0.07
0.17
0.08
0.08
0.63
Tm
0.02
0.01
0.01
0.01
0.01
0.01
0.01
0.003
0.03
0.001
0.02
0.003
0.001
0.07
Yb
0.16
0.14
0.14
0.12
0.12
0.11
0.10
0.08
0.28
0.07
0.15
0.08
0.09
0.57
Lu
0.02
0.01
0.01
0.01
0.01
0.01
0.01
0.004
0.03
0.004
0.02
0.004
0.01
0.07
LREY
8.72
6.83
6.81
6.71
6.80
6.29
6.14
5.25
13.80
4.61
7.52
4.08
4.51
16.83
MREY
2.92
2.32
2.63
2.25
2.31
1.97
1.85
1.51
4.06
1.10
2.11
0.98
1.13
7.44
HREY
0.46
0.34
0.39
0.31
0.33
0.29
0.27
0.20
0.74
0.16
0.40
0.18
0.20
1.54
REY
12.10
9.49
9.83
9.27
9.44
8.55
8.25
6.96
18.61
5.87
10.03
5.24
5.83
25.81
LaN/Lu N
1.04
1.58
1.11
1.51
1.64
2.48
1.79
3.10
1.09
2.79
1.21
2.47
1.82
0.45
LaN/Sm N
0.72
0.76
0.72
0.74
0.75
0.85
0.82
0.86
0.75
0.97
0.85
0.96
0.95
0.51
GdN/LuN
1.84
2.55
2.09
2.68
2.64
3.96
2.67
4.88
1.73
3.45
1.68
3.10
2.22
1.14
a
density reported as g/mL. LREY = La + Ce + Pr + Nd + Sm. MREY = Eu + Gd + Tb + Dy + Y. HREY = Ho + Er + Tm + Yb +
Lu. REY = REE + Y.
Table 8. REY Concentrations in DGC Fractions from Micronized LC S3-6 (µg/g, Cs-free Basis) Densitya
1.5102
1.5069
1.5009
1.4932
1.4846
1.4742
1.4638
1.4523
1.4412
1.4305
1.4175
1.4026
1.3864
1.3693
1.3529
La
2.91
0.92
0.95
0.99
3.08
0.87
0.87
1.02
0.92
1.13
0.86
0.88
0.80
0.81
1.10
Ce
6.30
2.43
2.51
2.54
8.47
2.31
2.31
2.54
2.35
2.55
2.20
2.20
2.15
2.22
2.68
Pr
0.72
0.30
0.31
0.32
0.76
0.28
0.26
0.31
0.28
0.32
0.25
0.27
0.25
0.25
0.33
Nd
2.80
1.30
1.44
1.41
3.05
1.22
1.23
1.41
1.27
1.48
1.13
1.25
1.14
1.20
1.46
Sm
0.79
0.52
0.56
0.51
0.83
0.49
0.47
0.47
0.48
0.50
0.43
0.45
0.40
0.43
0.50
Eu
0.14
0.06
0.06
0.06
0.11
0.06
0.05
0.05
0.05
0.06
0.05
0.04
0.04
0.04
0.05
33
ACS Paragon Plus Environment
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
Gd
702 703
1.02
0.89
0.97
0.92
1.25
0.84
0.87
0.84
Page 34 of 51
0.80
0.81
0.71
0.77
0.72
0.73
0.89
Tb
0.24
0.22
0.22
0.23
0.25
0.20
0.20
0.19
0.19
0.18
0.16
0.17
0.16
0.17
0.18
Dy
1.69
1.77
1.84
1.82
1.99
1.61
1.58
1.61
1.50
1.45
1.34
1.37
1.34
1.33
1.49
Y
7.17
9.44
9.56
9.65
10.02
8.93
8.80
8.65
8.33
8.15
7.59
7.50
7.23
7.53
8.08
Ho
0.34
0.35
0.35
0.36
0.40
0.32
0.32
0.32
0.30
0.28
0.27
0.27
0.25
0.27
0.28
Er
1.07
1.19
1.21
1.21
1.29
1.10
1.09
1.07
1.00
0.96
0.88
0.89
0.85
0.90
0.93
Tm
0.19
0.19
0.21
0.20
0.21
0.19
0.18
0.18
0.17
0.15
0.14
0.14
0.14
0.14
0.14
Yb
1.56
1.77
1.81
1.85
1.88
1.65
1.61
1.59
1.50
1.44
1.32
1.26
1.23
1.28
1.30
Lu
0.22
0.25
0.26
0.26
0.26
0.24
0.23
0.23
0.21
0.20
0.19
0.18
0.18
0.18
0.18
LREY
13.51
5.46
5.77
5.77
16.19
5.16
5.15
5.75
5.29
5.97
4.87
5.06
4.74
4.91
6.07
MREY
10.26
12.38
12.64
12.68
13.62
11.64
11.50
11.35
10.87
10.65
9.85
9.84
9.49
9.80
10.68
HREY
3.39
3.77
3.84
3.90
4.04
3.50
3.43
3.39
3.17
3.04
2.81
2.75
2.66
2.77
2.83
REY
27.16
21.60
22.25
22.34
33.85
20.30
20.08
20.48
19.33
19.66
17.52
17.64
16.88
17.48
19.59
LaN/Lu N
0.13
0.04
0.04
0.04
0.12
0.04
0.04
0.04
0.04
0.06
0.05
0.05
0.04
0.05
0.06
LaN/Sm N
0.55
0.26
0.26
0.29
0.55
0.27
0.28
0.32
0.29
0.34
0.30
0.29
0.30
0.28
0.33
GdN/LuN
0.37
0.28
0.29
0.28
0.38
0.28
0.30
0.29
0.30
0.31
0.30
0.33
0.32
0.32
0.40
a
density reported as g/mL. LREY = La + Ce + Pr + Nd + Sm. MREY = Eu + Gd + Tb + Dy + Y. HREY = Ho + Er + Tm + Yb +
Lu. REY = REE + Y.
34
ACS Paragon Plus Environment
Figure 1
Page 35 of 51
(A)
100 90
(B)
70 60
80 70
Inertinite (vol. %)
Huminite (vol. %)
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
Energy & Fuels
60
y = 0.04 x + 35.36 R² = 0.59
50 40 30 20
y = -0.04 x + 64.10 R² = 0.59
50 40 30 20 10
10 0
0 0
200
400
600
800
1000
1200
1400
0
Ge concentration (μg/g)
200
400
600
800
1000
Ge concentration (μg/g)
ACS Paragon Plus Environment
1200
1400
Figure 2 (A)
Page 36 of 51
(C)
Wulantuga Inner Mongolia
c
Yunnan Province Lincang
0
Bangmai c
Zhongzhai
1km
Legend K1b
P1zs K2c
Q1
P1
gn
K1b
J3mn
by 1
Pt
Bangmai Formation
Unconformable Contact
P1zs
Legend 1
10 J3mn
P1zs
Faults
2
3
Q1
4
N2b
5
K2c
6
K1b
7 J3mn
8
J3by
9
P1gn
Xilinhaote Pt1by
K1b
Biotite Granite
gn
J3by
N2b
n
Pt1by
Area of Ge-rich lignites
P1 al fie ld Co
Sh en gli
gn P1 K1b
Two-mica granite
J3by
bn C2
gn P1 bn C2
(B)
0
Dazhai
1000km
J3m
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
Energy & Fuels
P1zs
11 C2bn
12 Pt1by
13
14
15
16
17
18
1 unconformity, 2 Ge-coal deposit, 3 Quaternary, 4 Bogedawula Fm. of Tertiary, 5 Erlian Fm of upper Cretaceous, 6 Beiyanhua Fm. of lower Cretaceous, 7 Manitu Fm. of upper Jurassic, 8 Beiyingaolao Fm. of upper Jurassic,
9 Gegenaobao Fm. of lower Permian, 10 Zesi Fm. of lower Permian, 11 Benbatu Fm. of upper Carboniferous, 12 Baoyintu Fm. of Proterozoic, 13 Quaternary basalt, 14 Hercynian diorite, 15 Hercynian granodiorite, Plusgranite, Environment 15km ACS Paragon 16 Mesozoic 17 Fault, 18 City
Figure 3
Page 37 of 51
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
Energy & Fuels
(A)
20 μm
(B)
20 μm 20 μm
Densinite
Fusinite
Semifusinite
Fusinite
Textinite
Huminite
(C)
20 μm 20 μm
(D)
20 μm 20 μm
Corpohuminite Pyrite
Pyrite
Densinite
Densinite Funginite
Densinite
ACS Paragon Plus Environment
Figure 4 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
Energy & Fuels
(A)
20 μm
Page 38 of 51
(B)
20 μm
Densinite Huminite Funginite Semifusinite
Pyrite
Ulminite
Fusinite
Fusinite
20 μm
(C)
(D)
20 μm
Densinite Pyrite
Pyrite
Densinite
Ulminite
ACS Paragon Plus Environment
Page 39 of 51
Energy & Fuels
Figure 5(A) 20 μm
1.4266
20 μm
1.4074
20 μm
20 μm
1.4596
1.4871
20 μm
20 μm
20 μm
1.4443
1.4742
1.4985
100
Normalized Weight (%)
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
(A)
80
Micro WLTG C6-2 60
40 20 0 1.20
1.25
1.30
1.35
1.40
Density (g/mL)
ACS Paragon Plus Environment
1.45
1.50
1.55
1.60
Energy & Fuels
Figure 5(B) 20 μm
20 μm
20 μm
20 μm
1.3642
1.4187
1.4699
20 μm
20 μm
20 μm
1.3382
1.3912
1.4453
1.4952
100
Normalized Weight (%)
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 40 of 51
(B)
80
Demin WLTG C6-2 60 40 20 0 1.20
1.25
1.30
1.35
1.40
Density (g/mL)
ACS Paragon Plus Environment
1.45
1.50
1.55
1.60
Page 41 of 51
Energy & Fuels
Figure 5(C)
20 μm
20 μm
20 μm
1.4305
1.4523
1.4742
20 μm
20 μm
1.4175
20 μm
20 μm
1.4412
1.4638
1.4846
100
Normalized Weight (%)
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
(C)
80
Micro LC S3-6 60 40 20 0 1.20
1.25
1.30
1.35
1.40
Density (g/mL)
ACS Paragon Plus Environment
1.45
1.50
1.55
1.60
Energy & Fuels
Figure 5(D) 20 μm
20 μm
1.3284
20 μm
1.3660
1.4021
20 μm
20 μm
1.3096
20 μm
1.3471
20 μm
1.3844
1.4172
100
Normalized Weight (%)
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 42 of 51
(D)
80
Demin LC S3-6 60 40 20 0 1.20
1.25
1.30
1.35
1.40
Density (g/mL)
ACS Paragon Plus Environment
1.45
1.50
1.55
1.60
Figure 6
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
Energy & Fuels
Element concentration (μg/g)
Page 43 of 51
1000 900 800 700 600 500 400 300 200 100 0
(A)
25
(B)
20 15 Micro WLTG C6-2 Demin WLTG C6-2
Micro WLTG C6-2 10
Demin WLTG C6-2
5 0 Ge
As
Sb
W
LREY
1600
(C)
1400 1200 1000 800
Micro LC S3-6
600
Demin LC S3-6
400 200 0 Be
Ge
As
Nb
Sb
W
U
MREY
HREY
REY
50 45 40 35 30 25 20 15 10 5 0
(D)
Micro LC S3-6 Demin LC S3-6
LREY
ACS Paragon Plus Environment
MREY
HREY
REY
Figure 7
Page 44 of 51
WLTG C6-2 Be 12
H
V 3.0
I
10
H
Co 0.8
I
H
Cu 12
I
2.5
H
I
10
0.6
Trace element concentration (μg/g)
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
Energy & Fuels
8
2.0
6
1.5
4
1.0
8 0.4
6 4
0.2 2
0.5
0 1.35
0.0 1.40
1.45
1.50
1.55
1.60
2 1.35
1.40
1.45
Ga 1.6
H
1.50
1.55
0 1.35
1.60
1.40
1.45
250
1.2
H
1.55
1.60
1.40
1.45
As
Ge I
1.50
0 1.35
500
I
200
400
150
300
H
1.50
1.55
1.60
1.50
1.55
1.60
1.55
1.60
Zr 8
I
H
I
6
0.8
4
0.4 0.0 1.35
1.40
1.45
1.50
1.55
1.60
100
200
50
100
0 1.35
1.40
1.45
Sb 60
H
1.50
1.55
1.60
1.40
1.45
Hf 0.25
I
50
H
1.50
1.55
1.60
0.8
I
H
1.2
I
0.6 0.4
0.2
0.05
0.2
0.00 1.50
1.55
1.60
I
0.8
0.10
1.45
H
1.0
0.4
1.40
1.45
0.6
30
10
1.40
Pb
0.15
20
0 1.35
Tl
0.20
40
0 1.35
0 1.35
2
1.35
1.40
1.45
1.50
1.55
1.60
0 1.35
Density (g/mL) ACS Paragon Plus Environment
0.0 1.40
1.45
1.50
1.55
1.60
1.35
1.40
1.45
1.50
Page 45 of 51
Energy & Fuels
Figure 8
WLTG C6-2 Li 3.5
H
3.0
Sc 3.0
I
H
Cr 8
I
H
7
2.5
Ni 6
I
H
I
5
6
2.5
2.0
2.0
4
3
3
1.0
1.0
4
5
1.5
1.5
2
2
0.5
0.5
0.0
0.0 1.35
Trace element concentration (μg/g)
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
1.40
1.45
1.50
1.55
1.60
1.35
1.40
1.45
1.50
H
120
0.30
I
80 60 40 20 1.40
1.45
H
0.25
100
0 1.35
1.50
H
1.60
1.40
1.45
1.55
3.0
H
0.15
1.5
0.10
1.0
0.05
0.5
1.50
1.55
1.60
20
H
1.50
1.55
1.60
1.50
1.55
1.60
1.50
1.55
1.60
I
0.00
0.0
10 5
1.35
1.40
1.45
1.50
1.55
1.60
1.35
1.40
1.45
H
1.50
1.55
1.60
0 1.35
1.40
1.45
Cd 0.04
I
0.3
H
Sn 0.20
I
H
I
0.16
0.03
0.12 0.2
0.02
0.2
0.08 0.1
0.1
1.40
1.45
1.50
1.55
1.60
0 1.35
0.01
25
H
1.40
1.45
1.50
1.55
1.60
140
I
1.35
1.40
1.45
H
120
15
1.2
I
1.60
0 1.35
1.40
1.45
H
U 0.25
I
H
I
0.20 0.15 0.10
0.4
0.05
0.2
20 1.55
1.35
0.6
40
1.50
1.60
0.8
60
5
1.55
1.0
80
10
1.50
Th
100
1.45
0.00
W
20
1.40
0.04
0.00
Ba
0 1.35
1.45
Sr
0.3
0 1.35
1.40
15 2.0
0.4
0.4
1.60
I
Mo I
1.55
2.5
0.20
1.60
1.50
0 1.35
Rb I
Nb 0.5
1.55
0 1.35
Se
Zn 140
1
1
0.0 1.40
1.45
1.50
1.55
1.60
0.00 1.35
Density (g/mL)
ACS Paragon Plus Environment
1.40
1.45
1.50
1.55
1.60
1.35
1.40
1.45
Energy & Fuels
Figure 9
LC S3-6 Be
V
100
Co
4
80
2 40
0.6
12
0.5
10
0.4
8
0.3
6
0.2
4
1
20 0 1.30
Cu
3
60
Trace element concentration (μg/g)
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 46 of 51
Peak 1.35
1.40
1.45
1.50
1.55
0 1.30
0.1
Peak 1.35
1.40
Ga
1.45
1.50
1.55
0 1.30
1.35
1.40
6
1.45
1.50
1.55
0 1.30
Peak 1.35
1.40
As
Ge
8
2
Peak
1.45
1.50
1.55
1.50
1.55
1.50
1.55
Zr
2000
400
10
1600
300
8
1200
6 200
4 800 2
4 100
400
0 1.30
Peak 1.35
1.40
1.45
1.50
0 1.30
1.55
Peak 1.35
1.40
Mo
1.45
1.50
1.55
0 1.30
2
Peak 1.35
1.40
Sn
8
4
6
3
4
1.45
1.50
1.55
0 1.30
Peak 1.35
1.40
Sb
1.45
Tl
50
2.5
40
2.0
30
1.5
20
1.0
10
0.5
2
2
1
0 1.30
Peak 1.35
1.40
1.45
1.50
1.55
0 1.30
Peak 1.35
1.40
Pb
1.45
1.50
1.55
0 1.30
80
12
1.2
60
8
0.8
40
4
0.4
20
Peak 1.40
1.40
1.45
1.50
1.55
0 1.30
Peak 1.35
1.40
1.45
1.45
1.50
1.55
0 1.30
1.50
1.55
1.50
1.55
Density (g/mL)
ACS Paragon Plus Environment
Peak 1.35
1.40
1.45
Peak
0.0
U
1.6
1.35
1.35
Bi
16
0 1.30
Peak
1.30
1.35
1.40
1.45
Page 47 of 51
Energy & Fuels
Figure 10
LC S3-6 Li
Sc
Cr
6
5
5
5
4
4
3
3
2
2
1
1
4
Ni 4 3
3
2
2 1 0 1.30
Trace element concentration (μg/g)
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
Peak 1.35
1.40
1.45
1.50
1.55
0 1.30
Peak 1.35
1.40
Zn
1.45
1.50
1.55
1
Peak
0 1.30
1.35
1.40
Peak 60
1.50
1.55
Peak 1.35
1.40
Rb
Se
80
1.45
0 1.30
0.8
16
0.6
12
1.45
1.50
1.55
1.50
1.55
1.50
1.55
1.50
1.55
Sr 20
Peak 16 12
40
8
0.4
8 20 0 1.30
4
0.2
1.35
1.40
1.45
1.50
0 1.30
1.55
Peak 1.35
1.40
Nb
1.45
1.50
1.55
0 1.30
Peak 1.35
1.40
Cd
30
1.45
1.50
1.55
0.020
0.3
25
10
0.012
20
0.008
15 10
0.1
1.35
1.40
1.45
0.004
0.0 1.50
1.55
1.30
1.35
1.40
1.45
1.50
1.55
1.30
1.35
1.40
Ta
1.45
1.50
1.55
1.35
1.40
1.45
3.0
Peak
2.5
3
300 2.0
0.3 2
200
1
100
1.5
0.2
1.0
0.1 0 1.30
Peak
Th
400
Peak
0 1.30
W
4
0.4
5
Peak
0.000
Hf 0.5
1.45
30
0.2
Peak
1.40
35
0.016
20
5
1.35
Ba
Peak
15
0 1.30
In
0.4
25
0 1.30
4
1.35
1.40
1.45
1.50
1.55
0 1.30
1.35
1.40
1.45
1.50
1.55
0 1.30
Density (g/mL) ACS Paragon Plus Environment
0.5
Peak 1.35
1.40
1.45
Peak
0.0 1.50
1.55
1.30
1.35
1.40
1.45
Figure 11 R² = 0.68
140
48
(B)
60 40
Sb (μg/g)
80
350 300 250
20 0 120
140
160
180
200
220
120
140
160
180
200
60 40 20
120
140
0
3.5 3.0 2.5
0.5
180
200
220
23
R² = 0.96
(F)
21 17 15 13 11 9 7
1.5 0.4
160
19
4.0
2.0
Nb (μg/g)
100
Ba (μg/g)
80
0.3
38
220
(E)
4.5
Ni (μg/g)
100
0.2
40
Ge (μg/g)
R² = 0.76
5.0
(D)
120
0.1
42
Ge (μg/g)
R² = 0.54
0
44
34 100
Ge (μg/g)
140
(C)
36
200 100
R² = 0.61
46
400
100
As (μg/g)
W (μg/g)
Page 48 of 51
R² = 0.34
450
(A)
120
W (μg/g)
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
Energy & Fuels
5 3
4
5
6
Cr (μg/g) ACS Paragon Plus Environment
7
8
0.0
0.5
1.0
1.5
Sc (μg/g)
2.0
2.5
3.0
Figure 12
Page 49 of 51
R² = 0.001
400
340
(A)
350
R² = 0.22
320
200 150
44
300 280 260
100
0 1000
1200
1400
1600
1200
1400
Ge (μg/g)
75
U (μg/g)
Be (μg/g)
70 60 50
1800
1400
1600
25
65
20
60 55
3.0
350
1200
1400
1600
200 150 100
10
1200
1400
1600
1800
Ge (μg/g)
R² = 0.61
2.4
(H)
(I)
R² = 0.50
2.3 2.2
2.0 1.5
2.1 2.0 1.9 1.8 1.7
1.0
50
1.6
0
0.5 0
5
10
15
20
25
30
35
1.5 50
150
Nb (μg/g)
250
350
450
2.1
R² = 0.90
30
(J)
1.2
Ba (μg/g)
1.1 1.0 0.9 0.8 0.7 2.3
2.5
2.7
Sn (μg/g)
2.5
2.9
3.1
2.7
2.9
3.1
Sn (μg/g)
R² = 0.89
R² = 0.89
30
(K)
25
2.1
2.3
W (μg/g)
(L)
25
Ba (μg/g)
1.3
15
0 1000
1800
Tl (μg/g)
Th (μg/g)
250
1800
5
2.5
300
1600
(F)
Ge (μg/g)
(G)
1400
R² = 0.06
30
(E)
70
45 1000
1800
R² = 0.85
400
1200
Ge (μg/g)
R² = 0.66
Ge (μg/g)
W (μg/g)
1600
50
1200
36
30 1000
Nb (μg/g)
(D)
80
40 1000
38
Ge (μg/g)
R² = 0.89
90
40
32
220 1000
1800
42
34
240
50
(C)
46
Sb (μg/g)
As (μg/g)
W (μg/g)
250
R² = 0.83
48
(B)
300
Bi (μg/g)
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
Energy & Fuels
20 15
20 15
10
10
5
5 1.5
2.0
2.5
3.0
3.5
4.0
Sc (μg/g) ACS Paragon Plus Environment
4.5
5.0
0
5
10
Sr (μg/g)
15
20
Figure 13
Energy & Fuels 30
H
LC S3-6
40
(A)
I
(B)
Peak
35
25 20 15 REY 10
LREY
5 MREY HREY
0 1.36
1.41
1.46
Density (g/mL)
1.51
1.56
REY (μg/g)
30
REY (μg/g)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
WLTG C6-2
Page 50 of 51
REY
25 20 15
LREY
10
MREY
5
HREY
0 1.34
ACS Paragon Plus Environment
1.39
1.44
Density (g/mL)
1.49
Figure 14
Page 51 of 51
0.35
(A) WLTG C6-2
0.30
Density (g/mL) 1.5515 1.5426 1.5333 1.5220 1.5106 1.4985 1.4871 1.4742 1.4596 1.4443 1.4266 1.4074 1.3879 1.3692
Samples/UCC
0.25 0.20 0.15 0.10 0.05 0.00 La
Ce
Pr
Nd
Sm
Eu
Gd
Tb
Dy
Y
Ho
Er
Tm
Yb
Lu
1.00
(B)
0.90
Density (g/mL)
LC S3-6
0.80
1.5102 1.5069 1.5009 1.4932 1.4846 1.4742 1.4638 1.4523 1.4412 1.4305 1.4175 1.4026 1.3864 1.3693 1.3529
0.70
Samples/UCC
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
Energy & Fuels
0.60 0.50 0.40 0.30 0.20 0.10 0.00 La
Ce
Pr
Nd
Sm
Eu
Gd
Tb ACS Paragon Plus Environment
Dy
Y
Ho
Er
Tm
Yb
Lu
