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International Journal of Coal Geology 57 (2004) 143 – 149
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Fluorine content and distribution pattern in Chinese coals
Kunli Luo a,*, Deyi Ren b, Lirong Xu a, Shifeng Dai b, Daiyong Cao b,
Fujian Feng a, Jian’an Tan a
a
Institute of Geographical Sciences and Natural Resource Research, CAS, Building 917, 3 Datun Road, Beijing 100101, China
b
China University of Mining and Technology, Beijing 100083, China
Received 13 April 2003; received in revised form 29 September 2003; accepted 9 October 2003
Abstract
About 300 coal samples were collected to study the fluorine content and distribution pattern in Chinese coals in different
coal basins and geologic periods. The Permo – Carboniferous and Jurassic coals in the North China Plate and Northwest China
account for nearly 90% of Chinese coals and their fluorine content is 20 – 300 mg/kg, mostly about 50 – 100 mg/kg. Fluorine
content of Permo – Carboniferous coals, the main steam coals in China, is 50 – 300 mg/kg; Jurassic coals 20 – 70 mg/kg. There
are great differences in fluorine content of Late Permian coals in Southwest China (50 – 3000 mg/kg), which accounts for only
7% of Chinese coals. According to the proportions of the coals with different fluorine content in Chinese coal resources, the
average fluorine content of Chinese coals is about 82 mg/kg, which is close to the world average (80 mg/kg). Most Chinese
coals are low-fluorine coals ( < 200 mg/kg).
Fluorine content in Chinese coals is closely related with structure position of coal basins, the degree of volcanic activity and
magma intrusion, as well as the age, and source of the volcanic and magmatic rock. Frequent volcanic activity and magma
intrusion is the main reason for fluorine-rich coals and stone coals in South Qinling Mountain (Daba Area) and Southwest
China, where fluorine content is about 50 – 3000 mg/kg. Fluorine content in all platform areas, where magma activity is less, is
comparatively low, about 20 – 200 mg/kg.
D 2004 Elsevier B.V. All rights reserved.
Keywords: Chinese coal; Fluorine content; Distribution pattern; Source
1. Introduction
Coal accounts for 75% of all energy consumed in
China, much more than oil, natural gas or hydropower. About 70% (1080 million tons) of the mined coal
is directly used as fuel (Fan and Pan, 1995; Wu, 1996;
* Corresponding author. Tel.: +86-10-64856503; fax: +86-1064851844.
E-mail address: [email protected] (K. Luo).
0166-5162/$ - see front matter D 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.coal.2003.10.003
Cheng, 1998). Coal may constitute 70% of the fossil
energy resources in China and will play a dominant
role in the near future. Fluorine is a noxious trace
element in coal. Fluorine is generally emitted as gases
such as HF, SiF4, CF4, etc., when coal is burned,
resulting in the contamination of atmosphere (Lu,
1996; Liu et al., 1999, 2000; Qi et al., 2000). HF is
10– 100 times more toxic than SO2 and is particularly
hazardous for animals and plants (Jeng et al., 1998;
Piekos and Paslawska, 1999; Notcutt and Davies,
2001). Fluorosis is endemic in China, e.g. Guizhou,
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K. Luo et al. / International Journal of Coal Geology 57 (2004) 143–149
Western Hunan, Southern Shaanxi, mainly resulted
from fluoride-rich coal combustion. China has more
cases of fluorosis than any other country, more than
40 million dental fluorosis patients and 2.6 million
skeletal fluorosis patients (both mainly distribution in
the North China Plate and a few areas of the South
China; Tan, 1989; Finkelman et al., 1999; Finkelman
and Gross, 1999).
Several studies have determined the fluorine content and distribution pattern in Chinese coals (Zheng
and Cai, 1988; Lu, 1996; Liu et al., 1999, 2000; Qi et
al., 2000; Luo et al., 2001; Chen and Tang, 2002). But
these studies focused on certain coal mines or coal
types. There are few integrated studies on fluorine
content of the Permo – Carboniferous and Jurassic
coals in the North China and Northwest China, which
are widely distributed and used.
Zheng and Cai (1988) first reported the average
fluorine content in Chinese coals, as 200 mg/kg on
average, much more than the world average for coal
(Swaine, 1990). But among their 337 coal samples,
100 samples ‘‘came from 20 provinces in China’’ and
no explanation of sampling locations were given; 193
samples from South China (Yunnan, Guizhou,
Sichuan, Hubei, Hunan and Guangxi Province), including 7 stone coal samples and 186 coal samples; 40
samples from the east edge of North China Plate and
the location of the other 4 four samples were not given.
There are three main problems with their studies:
First, their samples are not representative of all
Chinese coals, because most samples were collected
from South China, where only about 8% of Chinese
coals are mined, while only a few samples came from
6 six of the seven largest coal resource provinces—
Sinkiang, Inner Mongolia, Shanxi, Shaanxi, Ningxia
and Gansu.
Second, no explanation of sampling method was
given. There can be great differences in fluorine
content even in the same coal seam. Luo et al.
(1994) studied Silurian stone coal in Shaanxi Province
and found that the fluorine content of one lump of
stone coal was 82 mg/kg, but the another lump was
4200 mg/kg from different parts of the same coal
seam. So sampling method according to strict criterion
(strip sampling and channel sampling according to GB
482-1995 (Chinese sampling standard of coal)) is very
important, and the fluorine content of the lump of coal
sample is not representative of the coal seam.
Third, the relative proportions of Chinese coal
resource with different fluorine contents were not
taken into account when average fluorine content in
coals was estimated by Zheng and Cai (1988). The
average fluorine content of Chinese coal in their paper
mainly was based on the arithmetical average of their
samples.
In addition, Chen and Tang (2002) studied fluorine
content in Chinese coals and summarized the results
of other scientists, but the above problems can also be
found in their research.
Ren et al. (1999) reported the fluorine content was
100 – 3600 mg/kg by eight coal samples mainly collected from Xishan coal mine in Shanxi Province;
however, sampling locations were chosen because the
coal seam is in close proximity to basic igneous rocks
(about 1 m). Those coal samples also do not represent
Chinese coals overall.
Further study of the fluorine content and distribution pattern in Chinese coals is needed. For this paper
about 300 coal samples were collected to study the
fluorine content and distribution pattern in Chinese
coals according to their different coal basins and
geologic age.
2. Main character of Chinese coal resource
The spatial distribution of Chinese coals is quite
uneven, with much more in the North and West and
less in the South and East. The 11 western provinces
have about 5115 billion tons coal, accounting for
91.83% of total Chinese coal resource (5570 billion
tons). Coal resources are largest in seven western
provinces—Sinkiang, Inner Mongolia, Shanxi,
Shaanxi, Guizhou, Ningxia and Gansu, among which
the six northwestern provinces north of Kunlun-Qinling Mountains have about 84% of Chinese coal
resources, while the southwestern areas (mainly Guizhou and Yunnan) have only 7% (Zeng, 2001; Chen
and Zhang, 1993).
The main coal-forming periods in China were the
Pennsylvanian, Permian and Jurassic. The Permo –
Carboniferous coals are the main coals used for power
generation in China (Zeng, 2001), accounting for
nearly 58% of Chinese coals. Among them, Taiyuan
Formation of Pennsylvanian coals and Shanxi Formation of Early Permian coals account for 27% and 17%,
K. Luo et al. / International Journal of Coal Geology 57 (2004) 143–149
respectively, mainly in North China and Northwest
China; Shihezi Formation of Late Permian coals
account for about 3%, mainly in Northwest China;
Longtan Formation of Late Permian coals account for
about 10%, mainly in Southwest China (Yunnan and
Guizhou Province). Jurassic coal accounts for about
39% of Chinese coals (mainly in Northwest China)
and the other coals (mainly Triassic, Cretaceous and
Tertiary coals) about 5% (Chen and Zhang, 1993).
3. Samples collecting and analytical methods
Fluorine content in Chinese coals is closely related
to the structural position of coal basins, roughly
correlating with volcanic activity and magmatic intrusion, as well as the age of magmatic intrusion and the
source of the volcanic and magmatic rocks (Luo et al.,
1994, 2001, 2002; Luo and Zhang, 1996). Coals in the
same tectonic unit having the similar paleostructure,
paleogeography, paleoclimate, tectonism and metamorphism during and after the coal-forming process
will have the similar fluorine content (Luo et al.,
2001, 2002).
Therefore, it is reasonable to collect coal samples
and analyze their fluorine content according to their
structure positions and geologic ages than according
to coal type (Luo et al., 2002).
Coal samples were collected from the coal formed
in various coal-forming periods. Permo – Carboniferous coals, the main steam coals in the North China
Plate and the Northwest China, were sampled from
Hancheng Chenghe and Tongchuan mines (5#, 10#
and 11# coal) in Shaanxi province, including Liaoyuan
Mine in Hancheng (Permian coal of Shanxi Formation), Xiangshan, Sangshuping and Magouqu mines in
the Hancheng Mine, the Tongchuan Mine and the
Pubai Mine (Pennsylvanian coal of Taiyuan Formation)—the typical coal basin in west of North China
Plate. Samples also came from the Datong, Pingshuo
and Xishan mines in Shanxi province—the typical coal
basin in west of North China Plate; from 4#, 8# and 9#
coals of Pingyin Mine in Shandong province—the
typical coal basin in east part of North China Plate;
from the main coal mines in Guizhou, West Hunan and
Yunnan Provinces in Southwest China. Samples collecting methods in this paper are mainly channel
sampling and strip sampling according to GB 482-
145
1995 (Chinese sampling standard of coal seam), making a straight channel in the coal bed, then collecting
the coal and gangue in the channel as the sample (Yang
et al., 1998).
All samples were analyzed for fluorine by the
Northwest Geological Testing Center of Northwest
Geological Research Institute, Geological Testing
Center of Coal Academy of Sciences in Xi’an, Shaanxi
and Coal Testing Center of Shaanxi Quality Testing
Center. Alkali-fusion/fluorine ion-selective electrode
method was used to analyze some samples before
1998, and most samples were analyzed by pyrohydrolysis/fluorine ion-selective electrode method during 1999 –2002 in the above testing centers (Yang et
al., 1998). For quality control in chemical analysis, the
standard reference materials (GBW11122 (coal, China), GBW08402 (coal fly ash, China), Chinese Standard Sample Study Center, Chinese Academy of
Measurement Sciences) were randomly analyzed with
each batch of coal and gangue samples. The relative
standard deviation was less than 10% and the detection
limit was 10 9.
4. Average fluorine content in Chinese coals
Many factors should be taken into account when
fluorine content in coals is evaluated, such as the
different coal-forming basins, different coal-forming
periods, different coal types, especially their different
proportions to Chinese coal resource.
We use the following symbols to simplify the
formula:
A0—the average fluorine content in Jurassic coal
(about 39%);
B0—the average fluorine content in Pennsylvanian
coal (mainly Taiyuan Formation, about 27%);
C0—the average fluorine content in Early Permian
coal (mainly Shanxi Formation, about 17%)
D0—the average fluorine content in Late Permian
coal (mainly Longtan Formation, about 10%)
E0—the average fluorine content in coal of the
other periods (including Shihezi Formation Early
Permian and Neogene coal, about 5%).
So the average fluorine content in Chinese coals
( F) can be expressed as F = A0 39% + B0 27% +
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K. Luo et al. / International Journal of Coal Geology 57 (2004) 143–149
C0 17% + D0 10% + E0 5%, giving an average
of about 82 mg/kg, close to that in the world (80
mg/kg).
Fluorine-rich coal reserves are not large in China,
which only include Late Permian coals of the Longtan
Formation in Yunnan and Guizhou (only about 10%
of Chinese coal). Stone coals are not included in
Chinese coal resource, but they would make a great
impact on local human health because of their distribution in the South, which has low coal resources.
5. Fluorine distribution pattern in Chinese coals
Fluorine content in all platform areas, where magmatic activity was less active, is comparatively low,
about 50– 300 mg/kg. For example, fluorine content
of most Permo –Carboniferous coals is less than 200
mg/kg in North China Plate, in the Northwest China
and Yangzi Plate, mostly about 50 – 100 mg/kg. Fluorine content of coals in the platform may decrease
with their increase in metamorphic degree. Fluorine
Table 1
Fluorine content and distribution pattern in Chinese coals (mg/kg)
CoalSouth of China
forming
Sampling spot
epoch
J
South of Shaanxi
P2
Tiemu Temple,
Sichuan
Southwest of
Guizhou
Qujing, Yunnan
and Zhijin,
Guizhou
Liangshan
Moutain and
Huanyingshan
Moutain,
Sichuan
North of China
Number Marginal
Platform
of
platform
samples and
geosyncline
Coal
gangue
12
300 – 350 Shenfu,
Shaanxi
300 – 350 Sinkiang
400 – 500
2
12
20 – 50
400 – 1500
3
8
12
Coal gangue
20
200 – 250
20 – 50
200 – 400
100 – 200
300 – 400
400
50 – 380
200 – 300
Pingshuo,
Shanxi
Datong,
Shanxi
Weibei,
Shaanxi
Pingshuo,
Shanxi
Datong,
Shanxi
Weibei,
Shaanxi
Xishan,
Beijing
C2
1
Number Igneous
Platform
of
developing
samples province in
marginal
platform
50 – 1500
P1
S
O
Sampling
spot
Ankang, Shaanxi 20
Ankang, Shaanxi
5
South of Shaanxi, 30
Hunan and Hubei
6
60
50 – 250
200 – 500
(3#)
50 – 290
(2#,3#)
50 – 150
(8#,11#)
50 – 150
(8#)
50 – 150
150 – 500
(11#,10#,5#)
18
30
12
50
8
200 – 600
(8#)
400 – 3000
400 – 700
400 – 1500
Note: ‘‘ – ’’ is a hyphen and it means the range of fluorine content from 400 to 500 mg/kg generally; ‘‘#’’ in the back or the front of the number
commonly means the number of coal seam in China.
K. Luo et al. / International Journal of Coal Geology 57 (2004) 143–149
147
Table 2
Relation between fluorine content and igneous rock of coals in southwest China and Daba Area, Qinling Mountain
Sampling spot
Number of
Samples
Sampling mode
Rock type
Fluorine content
(g t 1)
Epoch
Distance from
igneous rock (m)
Sampling
depth (m)
Zhijin, Guizhou
Zhijin, Guizhou
Qujing, Yunnan
Qujing, Yunnan
Datong, Shanxi
Datong, Shanxi
Wamiao, Ziyang
Wamiao, Ziyang
Maoba, Ziyang
Tiefo, Langao
Haoping, Ziyang
Haoping, Ziyang
Haoping, Ziyang
2
2
2
2
2
2
2
4
5
3
2
5
5
strip sample
lump sample
strip sample
lump sample
lump sample
lump sample
channel sample
channel sample
channel sample
channel sample
channel sample
channel sample
lump sample
coal
coal
coal
coal
coal
coal
stone coal
stone coal
stone coal
stone coal
syenite-porphyry
stone coal
bottom of stone coal
52
1200
68
1100
950
215
1500
620
430
615
1618
2200
1500
P2
P2
P2
P2
C2
C2
>100
1
>50
1
2
30
1
5
100
10
1 (from stone coal)
2.0
3.4
2
0.2
2
2
0.2
0.1
2
1
1
1.5
10
3
0.1
content of anthracites, generally speaking, is less than
100 mg/kg and high rank bituminous coal is less than
150 mg/kg. Fluorine content in Chinese coals is also
1
1
2
1
S1
S1
S1
related with coal-forming periods and circumstances.
Permo – Carboniferous coals (11# and 5#) with high
rank are widely distributed in Northwest and North
Fig. 1. Map showing fluorine content and distribution pattern in Chinese coals.
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K. Luo et al. / International Journal of Coal Geology 57 (2004) 143–149
China, where fluorine content is about 50– 150 mg/
kg, a little lower than 2# and 3# Permian coals, where
fluorine content is about 150 mg/kg. Fluorine content
is about 100 mg/kg in Late Permian coal measures in
Yunnan and about 20 –50 mg/kg in Jurassic coals in
most coal basins in the Northwest China. Fluorine
content of coal gangue in Northwest and North China
is about 200 –700 mg/kg, much higher than coals in
the same strata. Whether in South or in North China,
fluorine content of coals is relatively low if there was
no influence of magmatic activity at the same or later
time (Table 1).
In geosyncline areas (e.g. the east of KunlunQinling Mountain-Daba Area in South Shaanxi and
Dabie Mountain in North Hubei) and on the edge of
platform areas (e.g. Southwest China), there have been
numerous tectonic movements, especially since Cambrian. Volcanism brought abundant fluorine into coal
basins and coal seams. Fluorine is more enriched by
absorption by organic matter and clay in coal-bearing
strata. It is very clear that volcanic activity and magma
intrusion are the primary reasons for fluorine-rich
coals in Daba Area, Dabie Mountain Area and Southwest China, where there was more volcanic activity
and magmatic intrusion during and after coal-forming
period than the on North China Plate. The fluorine
content in coal correlates negatively with the distance
from igneous rock in geosyncline areas and on the
edge of platform areas (Table 2).
Fig. 1 shows fluorine content and distribution pattern in Chinese coals. The Permo –Carboniferous and
Jurassic coals in North China and Northwest China are
mainly low-fluorine coals, accounting for nearly 90%
of Chinese coals. High-fluorine coals in China include
Permo – Carboniferous coals on the edge of platform
areas (e.g. Zhangjiakou of Hebei Province, Mentougou
of Beijing on the north edge of North China Plate) and
Late Permian coals of Longtan Formation in Yunnan
and Guizhou, but not all Late Permian coals in Yunnan
and Guizhou are high-fluorine coals. Stone coals are
not included in Chinese coal reserves, so most of
Chinese coals are low-fluorine coals.
6. Conclusions
Most Chinese coals are low-fluorine coals ( < 200
mg/kg). The average fluorine content in Chinese
coals is about 82 mg/kg, close to that in the world
(80 mg/kg).
Fluorine content in Chinese coals is closely related structural position of coal basins, the amount of
volcanic activity and magmatic intrusion, as well as
the age and the source of volcanic and magmatic
rocks. Frequent volcanic activity and magma intrusion is the main reason for fluorine-rich coals and
stone coals in geosynclines region and on the edge
of platform areas, such as Southeast Qinling Mountain (Daba Area), Dabie Mountain as well as southwest China, where fluorine content is about 50– 3000
g/kg. Fluorine content is quite low (about 50– 200
mg/kg) in the platform areas, where there is little
magma activity.
In China, low-fluorine coals are mainly distributed
in stable platforms in North China and Northwest
China. Medium- to high-fluorine coals are mainly in
Guizhou-Yunnan, where there was more volcanic
activity and magma intrusion during and after coalforming period than the North China Plate. Superhigh-fluorine coals include stone coal in igneous rock
in geosynclines region South Qinling Mountain and
Late Permian coals of Longtan Formation, occur in
the southwest of Yunnan and Guizhou, but not all Late
Permian coals in Yunnan and Guizhou are highfluorine coals, so not more than 3% of Chinese coals
are high-fluorine coals (stone coals are not included in
Chinese coal reserves). But most of high-fluorine
coals are anthracite coals and local people directly
use them as fuel for cooking and for warmth in winter.
So the high-fluorine and superhigh-fluorine coals
have resulted in serious indoor air pollution and
human health problems in Daba Area of South Qinling Mountain and Yunnan-Guizhou.
Acknowledgements
The authors express their heartfelt thanks to Dr.
Robert B. Finkelman, U.S. Geological Survey for his
help in editing the English text. We also like to thank
Wei Bingren, Wang Biyu, Gao Bolin, Zhao Xiangyou, the staff in Xiangshan and Magouqu Coal
Mine, the staff in Coal Power Group, and some
students of Geology Department in Xi’an University
of Science and Technology for their valuable help.
The Chinese Key Project for the Chinese Tenth Five-
K. Luo et al. / International Journal of Coal Geology 57 (2004) 143–149
Year Plan (Grant No. 2001BA704B03) and Chinese
National Key Project for Basic Research (Grant No.
G1999022212-02) as well as the Knowledge Innovation Foundation of Institute of Geographical
Sciences and Natural Resource, Chinese Academy of
Sciences (Grant No. SJ10G-A01-03) supported this
work.
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