americanbased-110

Distributions of Minor and Trace Elements in Chinese Coals

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扩展资料：

一九八八年，宝洁公司在广州成立了在中国的第一家合资企业—广州宝洁有限公司，从此开始了其中国业务发展的历程。宝洁大中华区总部位于广州，在广州、北京、上海、成都、天津、东莞等地设有多家分公司及工厂，员工总数超过六千三百人，在华投资总额超过十亿美元。

宝洁公司是中国最大的日用消费品公司，大中华区年销售额超过二十亿美元。海飞丝、飘柔、舒肤佳、玉兰油、帮宝适、汰渍及吉列等品牌在各自的产品领域内都处于领先的市场地位。

中国宝洁是宝洁全球业务增长速度最快的区域市场之一。宝洁大中华区的销售量已位居宝洁全球区域市场中的第二位，销售额也已位居前五位。

在宝洁大中华区，越来越多的中国籍员工担任起重要的管理职位，中国籍的员工占员工总数的98%以上，宝洁大中华区已成为向宝洁其他市场的人才输出地。

参考资料来源：百度百科-宝洁

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Abstract The concentrations of forty-five elements in 137 Chinese coals collected from the main coal fields and representing the main coal-forming periods w ere determined using instrumental neutron activation analysis ( INAA) ，atomic absorption spectrometry ( AAS ) ，inductively coupled plasma atomic emission spectrometry ( ICP-AES ) ，and atomic fluorescence spectrometry ( AFS ) . Among the elements determined are the follow ing minor and trace elements w hich are important to environmental protection and human health: As，Cd，Pb，Hg，Se，Mn，Ni，Cu，Zn，Sb，Co，Mo， F，Cl，V，Ba，U and Th. The ranges and means of concentrations of these elements are given. Comparison w ith w orld averages and geometric means of concentrations in American coals show s that the concentrations of most elements are higher in Chinese coals. How ever，it is necessary to point out that although the samples are representative，the number of samples is small. Hence，these are only preliminary results. Finally，five major genetic types of enrichments of minor and trace elements in Chinese coals are proposed on the basis of Chinese coal geology，namely，source-rock- controlled type; sedimentation-controlled type; magmatic / hydrothermal controlled type; fault-cont- rolled type; and groundw ater-controlled type.  1999 Elsevier Science B. V. All rights reserved.。

Key words minor and trace elements distribution Chinese coals。

1. Introduction。

Concentration limits for As，Cr，Pb，Hg，Cd，Se，Mn，Ni，Cu，Zn，F，Cl，Sb，Co， Mo，Be，Ba，V，Tl，Th，U and Ag have been set as relevant standards of w ater and air quality in many countries. These elements commonly occur in coals and coal-derived products and com- bustion residues. Therefore，today，many countries are concerned about environmental pollution caused by coal mining，coal benefication and coal combustion. In China，the w orld’s largest coal producer and user，74% of fuel and energy come from coal，and 64% of the chemical ma- terials are coal-derived products. The output of coal amounted to 1. 35 billion tons in 1996，and is projected to be about 1. 4 － 1. 5 billion tons in 2000. The amount of coal combustion residues w as 105 million tons in 1996，and w ill be 150 million tons in 2000. Therefore，the Chinese go- vernment is putting heavy emphasis on the pollution derived from coal mining and coal utiliza- tion.。

In this paper，preliminary results of a study on the distribution of minor and trace elements in Chinese coals is presented.。

2. Main coal-forming periods and coal basins in China。

In China，there are eight main coal-forming periods，namely，Late Carboniferous ( C2) ， Early Permian ( P1) ，Late Permian ( P2) ，Late Triassic ( T3) ，Early-Middle Jurassic ( J1 － 2) ， Late Jurassic to Early Cretaceous ( J3－ K1) ，Eogene ( E) ，and Neogene ( N) . Late Carbonifer- ous and Early Permian coal basins lie in the northern part of China; Late Permian coals occur in the southern part of China; Late Triassic coals are present in the Sichuan Basin，the Zixing Coal Field，and the Shanbei Coal Field; Early-Middle Jurassic basins lie in the northw estern and northern parts of China; Late Jurassic to Early Cretaceous basins are located in the northeastern part of China. Eogene coal basins are in present northeastern China and Neogene coal basins are formed in southw estern China.。

3. Samples collecting and analytical methods。

Coal samples w ere collected from the main coal fields formed in the various coal-forming periods. The method of sample-collecting is in accordance w ith the Chinese standard for collec- ting w hole-coal-seam samples( GB482-79，see Han et al. ，1996) . The coal samples are collect- ed continuously from the top to bottom of a coal seam，w ith dimensions of 5 cm × 5 cm，exclu- ding partings more than 1 cm thick.。

Lead，cadmium，nickel，copper，zinc and fluorine w ere determined using atomic absorp- tion spectrometry . ( AAS) ，or inductively coupled plasma atomic emission spectrometry ( ICP- AES) . Mercury w as determined by atomic fluorescence spectrometry ( AFS) . The remainder of minor and trace elements were determined by instrumental neutron activation analysis ( INAA) .。

4. Results of analysis。

The ranges，arithmetic means and geometric means for 45 minor and trace elements in Chi- nese coals are listed in Table 1. Table 1 also contains tw o enrichment factors ( EF，formula 1) ， the first value w as calculated from the arithmetic means，and the second value from the geomet- ric means. In Table 2，the ranges，arithmetic means and geometric means for these elements are compared to data for USA coals and w orld arithmetic means. Table 3 contains the geometric means for concentrations of elements in different coal-forming periods in China. Notes to Table 2:。

aFrom Finkelman ( 1993) .。

bFrom Valkovic ( 1983) .。

cFrom Yudovich et al. ( 1985) ，the former for lignite，the latter for bituminous coals.。

dFrom Swaine ( 1990) ，data for most coals.。

AM : arithmetic mean; GM : geometric mean; Max. : maximum of concentrations; No. : number of samples.。

Table 1 Concentrations of minor and trace elements in Chinese coals，values are in ppm except where noted。

Standard deviation is for arithmetic mean. EF = enrichment factor. ∑REE = La + Ce + Sm + Nd + Eu + Tb + Yb + Lu;L / H = ( La + Ce + Sm + Nd + Eu) / ( Tb + Yb + Lu) .。

Table 2 Concentrations of minor and trace elements in Chinese coals，USA coals and World average， values are in ppm except where noted。

Table 3 The geometric means of concentrations in Chinese coals from different coal-forming periods，values are in ppm except where noted。

任德贻煤岩学和煤地球化学论文选辑。

w here:

Ai= the concentration mean of element i in coal。

B = the concentration mean of scandium in Chinese coal ( Table 1)。

Ci= the clarke value of element i ( Taylor，1964)。

D = the clarke value of scandium ( 22 ppm，Taylor，1964) .。

From the above tables，the follow ing preliminary conclusions can be draw n. In comparison w ith the crust of the Earth( Taylor，1964; Zhao and Zhang，1988) ，the follow ing elements are higher in Chinese coals than in the crust of the Earth: Hg，Se，As，Sb，Mo，Cd，Pb，U，F and Th. The value of EF for each of these elements in Chinese coals is more than 3.。

The arithmetic mean of concentrations for W，Cl，Br in Chinese coals are less than，Sb and Zn about equal to，and the remainder minor and trace elements have arithmetic means that are more than the w orld arithmetic means for the corresponding elements in coal. The high arith- metic mean of As，276. 61 ppm，is due to the contribution of a single sample from southw est China containing 3. 2% As. The distribution of coals w ith high concentrations of As are very local. Hence，the geometric mean of 4. 26 ppm As should be a more representative value for the As content in Chinese coals. Compared to United States coals，the geometric mean of concentra- tions of B，Br and As in Chinese coals are less than，Sb about equal to，and in the remaining minor and trace elements are more than the means for the elements in USA coals.。

It is w orth pointing out that As in the highest arsenic-bearing coal sample of H2( 3. 2% ) from Haizhi Tow nship，Xingren County，Guizhou Province，southw est China is not in a crys- talline phase; no arsenic-bearing minerals w ere detected by X-ray diffraction，electron probe， scanning electron microscopy，and transmission electron microscopy. How ever，Belkin et al. ( 1997) found “small grains and veins of arsenopyrite and As-bearing pyrite”in the H2coal sample. Using X-ray absorption fine structure ( XAFS ) ，we found that arsenic in the high- arsenic coal samples of H2，G4，J10，J5，H7，and H9w ith the As contents of 3. 2% ，1112 ppm， 501 ppm，131. 5 ppm，120 ppm，94. 1 ppm，respectively，occurs in macerals，and is com- bined w ith oxygen; the coordination numbers in most samples are 4，only in the sample H it is 3( Zhao et al. ，1997) . Thus，for these high-arsenic coal samples，the preponderance of the As is in the 5 + valence state，w hich is consistent w ith the results obtained by Belkin et al. ( 1997) .。

There are some obvious differences in the concentrations of minor and trace elements in coals from different coal-forming periods. The follow ing elements in Eogene coals are richer than in other coals: Ni，Co and Cr. Tungsten，U，As，Zn，Cr，Sb，Ni，and Co are enriched in Late Triassic coals. Most minor and trace elements in Early-Middle Jurassic coals are low er than in other coals，for example，Sb，Zn，Cr，and Th. Most minor and trace elements in Late Per- mian coals such as Cd，As，Sb，Fe，Co，Ni，Mo，Se，Cr and Cu are enriched. The contents of Pb，Cl，Br and Th are higher in Early Permian coals，and Hg，Sr and U are higher in Late。

Carboniferous coals ( Table 3) . 。

5. Genetic types of enrichment of minor and trace elements。

There are many factors w hich control the enrichment of minor and trace elements in coal. Based on Chinese coal geology，w e propose five major genetic types of enrichment to account for the concentrations of minor and trace elements in Chinese coals: source-rock controlled type; sedimentation-controlled type; magmatic / hydrothermal-controlled type; fault- controlled type; and groundw ater-controlled type.。

5. 1 Source rock-controlled type。

This genetic type is the most characteristic for coals deposited in small fault-controlled ba- sins. The source region is near the basin; the sedimentation rate of basins is rapid and sediments fill the basin quickly. Hence，elements w ith high concentrations in the source rocks are com- monly enriched in these coals. For example，coals from the Eogene Shengbei Coal Field and the Jurassic Beipiao Coal Field in Liaoning Province have high concentrations of Cr，Zn and Ni because the source rocks for the tw o coal fields are basalts in w hich the concentrations of these elements are high.。

5. 2 Sedimentation-controlled type。

Coals deposited on tidal flat environments of restricted carbonate platforms belong to this genetic type. These kinds of sedimentary environments often have algae grow ing，and a low Eh value，forming a reducing environment. More primitive organisms have a strong capacity to en- rich some elements. Some elements，especially chalcophile elements，are readily precipitated in reducing environments.。

Coals formed in the Late Permian from the southern part of China are often attributed to this genetic type. For example，the Late Permian coals from Guiding，Ziyun in Guizhou Prov- ince and Ganhe in Yunnan Province have high U，M o and V ( Ren et al. ，1995; Zhao， 1997) .。

Other examples of this type are the Late Carboniferous coals from Shanxi Province in the No. 15 coal seam of the Jincheng Coal Field w as deposited on a tidal flat. The coal-accumulating sw amp w as strongly influenced by marine w aters and had a reducing environment，hence the contents of most of elements are higher. The top of this coal seam contains humosapropelic coals w ith 8. 40% alginites，83. 70% humosapropelic groundmass，and 4. 70% pyrite. The contents of As，Se，Sr，Na and Mo in the humosapropelic coals are 22. 3 ppm，138 ppm，427 ppm， 337 ppm and 16. 30 ppm，respectively，w hich are 47，17，8，5 and 3 times those of vitrinites from the same coals ( Wang，1994) . Obviously，algae play an important role in enrichment of these elements. Higher contents of pyrite and a more reducing environment may be the reason for the higher contents of these elements in the humosapropels. The No. 14 coal seam of the Yangquan Coal Field w as deposited in the intertidal zone，immediately overlain by lime- stone. Ash content of these coals is low ，8. 74% ，consisting of clay minerals，w ith rare py- rite. Vitrinite content is more than 90% . The concentrations of U，V，Mo，Cr and Ni are 49 ppm，84. 1 ppm，56. 9 ppm，26. 2 ppm，and 37 ppm，respectively. The high contents of these elements in Yangquan No. 14 Coal are due to its special sedimentary environment ( Zhao， 1997) .。

5. 3 Magmatic /hydrothermal-controlled type。

This genetic type exists extensively in China because of the w idespread magmatic activity in Mesozoic and Cenozoic time. Magma intrusions and related hydrothermal activity w ere espe- cially common during the Yanshan Orogenesis of the Mesozoic period.。

The Early Permian Shanxi formation coals in Shanxi Province have similar sedimentary en- vironments. The differences in the concentrations of elements in these coals are mainly con- trolled by hydrothermal activity during the Yanshan Orogenesis in the Mesozoic. For example， the concentrations of Cl，Br，Hg，Zn and Pb in coals from the Gujiao mining area are higher than those in other regions ow ing to the intrusions of alkaline magma and hydrothermal activi- ty. Another example is from Ling County ( Shanxi Prov. ) in w hich there are also alkaline intru- sions，and the contents of volatile elements，such as Cl，Br，Hg，Se and Sb in the coals from these areas，are relatively high ( Zhao，1997) .。

5. 4 Fault-controlled type。

The coals deposited in coal basins in the vicinity of deep and large faults belong to this ge- netic type. The kinds of elements enriched in those coals are related to the chemical properties of fluid flux from faults. Zhou ( 1983) and Gu( 1990) found the enrichment of As in Tertiary coals from Yunnan Prov. w as related to the Sanjiang fault zones to the w est of these coal basins.。

5. 5 Groundwater-controlled type。

This genetic type exists in almost every coal basin. The kinds of elements concentrated in the coals depend on the chemical properties of the groundw ater，the relation of the w ater level to the coal seam，and the chemical properties of the country rocks. For example，the high con- centrations of Ca，Mn，Ba，Sr，Zn and Cd in the Late Carboniferous No. 9 Coal from Pingshuo Surface Mine in Shanxi Prov. are related to high concentrations of epigenetic carbonate minerals w hich w ere deposited from the ground-w ater( Zhao，1997) .。

6. Conclusions

The ranges and means of concentrations of forty-five elements in Chinese coals are given. Comparisons w ith w orld averages and geometric means of concentrations in American coals show s that the concentrations of most of minor and trace elements in Chinese coals are high- er. Five major genetic types of enrichment are proposed to account for the concentrations of minor and trace elements in Chinese coals.。

Further detailed sampling and geological and chemical studies on the five genetic types w ill help refine these models. Considering the potential environmental hazards of some elements ( for example，As and Hg ) contained in coal，it w ill be very important to be able to predict and delineate，either parts of a coal seam，or particular seams in a basin w hich contain higher con- centrations of particular elements.。

Acknow ledgements。

The research w as funded and supported by the National Natural Science Foundation of China ( No. 49372124 ) . We were indebted to Prof. Dexin Han，a member of Chinese Academy of Engineering，Prof. Pengfei Zhang and Prof. Aiyun Zhang for their advice. We are grateful to Dr. Robert B. Finkelman，Dr. C. -L. Chou and Dr. Harvey E. Belkin for their review s of the manuscript and constructive comments.。

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( 本文由任德贻、赵峰华、王运泉、杨绍晋合著，原载 International Journal of Coal Geolo-gy，1999 年第 40 期)。

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