Geochemical characteristics of Galandrud coal in central Alborz, Iran Geochemical characteristics of Galandrud coal in central Alborz, Iran

Geochemical characteristics of Galandrud coal in central Alborz, Iran

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  • 论文作者:Ardebili Leila,Babazadeh Vasef
  • 作者单位:Department of Geology,Department of Mineralogy,Geological Survey and Mineral Exploration of Iran
  • 更新时间:2020-06-12
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Intemational Joumal of Mining Soience and Technology 22(2012)101-1Contents lists available at SciVerse Science DirectInternational Journal of Mining Science and TechnologyELSEVIERjournalhomepagewww.elsevier.com/locate/ijmstGeochemical characteristics of Galandrud coal in central alborz. IranArdebili Leila a*, Babazadeh Vasef Mammadov Mousa Navi Pedramersity, Ardebil 551.Department of Mineralogy. Geology370145, Azerbaijan'Geological Survey and Mineral Exploration of Iran, Tehran 13185-1494, ItARTICLE INFOABSTRACTThis study focuses on the geochemistry of trace elements and parameters of coal quality of bituminousReceived 28 March 2011Dal belonging to the upper Triassic-lower Jurassic era, collected from the Galandrud region in Centraleceived in revised form 10 May 2011Alborz. northern Iran. Galandrud coal on an air-dried basis are characterized by broad variation in theAvailable online 20 March 2012amount of ash(ranging from 6, 4* to 12.735] a high content of volatile matter(33 32-37. 45%)and highgross calorific values(7430-8880 kcal/kg. The mineral matter of the coal samples studied is made up ofdolomite(>90). quartz, sphalerite, galena, pyrite and clay minerals. Major elements are positively cor-related with ash content suggesting an association with inorganic constituents. Based on statistical anal-10-)c(65×106-1942×10M(56×106.182×10-6N(29×1061529×10-yyses, concentrations of trace elements such as Co(51.3 x 106-152.9 x 10-)Ba(368 x 10-6-3297.4(245.5 x 10--520 x 10)are higher than world coal averages. However, low concentration of some vol-atile elements such as As, Hg and U are present in low concentrations of the various types ofe 2012 Published by Elsevier B V. on behalf of China University of Mining1 IntroductionMn, Mo, Ni, P, Pb, Sb, Se, Sn, Tl, Th, v, U and an; among these As,Be, Cd, Cr, Co, Hg, Mn, Ni, Pb, sb, Se and radio-nuclides such as U,Coal is one of the primary energy sources for many developed V and Th are identified as potentially hazardous airand developing countries, although its mining, processing, combus(HAPs)by the American Clean Air Act Amendments in 1990on and post-combustion waste products expedite thermal pollu- In Iran, coal deposits frorm the upper Triassic-lower Jurassic eration, particulate release (smog), sulfur emissions, acid rain, are limited to a few regions(Alborz, Kerman and khorasan)and notgreenhouse effect, the emission of trace elements and may also enough studies have been conducted on the geochemistry of tracecause environmental and human health problems [1-3]. Recently elements in Iranian coal. Two of the previous works on this subjectscientists have become more interested in the causes of these prob- are the following: a preliminary study on geochemistry of coals inlems and are determined to have coal used more efficiently [4-9). the loshan coalfield by Yazdi and shiravani [26 and a brief referProperties and characteristics of coal depend on its combustible ence for geochemistry of four coal samples from northern Iran byorganic and inorganic constituents. Among the parameters of coal Goodarzi et al. 17). The aim of the present study is to investigatequality, trace elements may have a great impact on the environ the geochemistry of trace elements in Galandrud coal, located inment, human health, technology and the economy [5.6.8]Central Alborz. northern Iran.A large number of trace elements can be classified as natural(eg-.weathering of rocks, volcanoes. thermal springs)and anthro- 2. Study areapogenic(e. g. metal mining and smelting, combustion of coal, agricultural activities). Trace elements are present in coal in eitherBlack coal deposits from theorganic or inorganic form and most of them occur simultaneously are very common globally butassicin both forms at concentrations that vary at different stages of coal- coal is rare(12.13). In Iran,coalification(3. 7, 10). Most trace elements are associated with mineralmatter in coal, largely concentrations of ash: however, certain elesic-Fower Jurassic)era and the principal coalfields are located atAlborz and khorasan(northern iran) and in Kerman(centments have an affinity for organic matter [3, 111. Finkelman (1995) (14)(Fig. 1)discussed 25 potential environmental hazardous trace elementsOur study focuses on the central Alborz zon( PHTEs)in coaL, including Ag. As. B, Ba, Be, Ca, Cl, Cr. Co, Cu, F Hg. Although, the coal deposits of Central Alborz haIn van中国煤化工dedCorresponding author. Tel: +98 451 551Cg strata of Galandrud areE-mail address: lardebiliegmaCNMH Guntain range and are as2095-26865t matter c 2012 Published by Elsevier B.V. on behalf of China University of Mining& Technology.do:a.01601106010L Ardebili et aL /International Journal of Mining Science and Technology 22(2012)101-1060 1023n kmasian sKhorasanCaspian seaCollieC→ pitalCFig. 1. Map showing the location of Galandrud coal in the central Alborz zone, Iran.far as 20 km south of Ruyan(Alamdeh)town(between 36 34 /36 keybeds of sandstone and has 32 coal seams, approximate 50 cmoN and 51 19/51 56 E, Fig. 1)in Mazandaran province. The thick, of mainly atoctone origin, of which 17 layers are of a workalandrud coalfield with its longitudinal extension of about able thickness 19 Because of these characteristics, this section of00 km has deposits at an elevation of more than 1240 m. As a re- the Kalarize part is known as CBM(Coal-Bearing Measures)(Fig. 2).alt of the humid climate(the average annual rainfall is more than850 mm)and consequently the expansion of forest vegetation in 3. Method of studythe Galandrud region, the coal beds are totally masked by denseSix coal samples wereCoal in Central Alborz is part of the Shemshak formatfrom a galandrud mine Standardproximate and ultimatewere carried out in the Iraniancomprises four parts(Ekraser, Lalehband, Kalariz and Javaherdeh) Geological Institute forrveys and exploration. Minerathat are folded as synclines with a WNW-ESE axis and are limiteds of each coal sample were perby Triassic limestone(the Elika formation)and cretaceous lime- formed on a polished section of coal using a Leitz MPVSPtone [ 15-18]. In the Galandrud region, the Kalarize part of Shem- microscope at the Geology Department of Baku State Universityshak. about 600-700 m thick, has been located between two0rust fauTriassic sed Rg Cretaceous sed中国煤化工AnticlineCoal bedAN mArgilite bedCNMHGFig. 2. Generalized geology map and stratigraphic sequence of the Galandrud coalfieldL Ardebili et al/Intemational Jourmal of Mining Science and Technology 22(2012)101-106The major elements and most trace elements were analyzedPyrite in Galandrud coal is rare and where it occurs of epigefrom bulk dried coal samples using ICP-AES(for Al, F, Mg. Ca, K, netic or syngenetic form. the syngenetic pyrite was identified fromNa, Ti, B, Ba, Cr, Cu, Mn, Sr and V)and ICP-MS (for As, Ge, Li, Mo, its framboid texture( Fig. 3d)and the epigenetic type is fractureNi, Pb, Rb, Sn, Th and u)at the laboratories of the Iranian Geological filling in this coal( Fig. 3c) Sphalerite was determined in all theInstitute for mineral surveys and exploration.samples( Fig 3a), but galena in only one sample(Fig. 3b).Using the SPSS statistical program, Pearson correlation coeffents were obtained to determine relationships between concen- 4.3. Modes of occurrence of the major elements and concentrationtrations of trace elets and ash yields.The major elements in coal are present as minerals rather than4. Results and discussionas organic matter. Major element geochemistry may therefore beused to document mineralogical variation and to stablish ele-4.1 Proximate and ultimate analysesment-mineral associations[8, 10, 21-23).The results of major element analyses of the galandrud coTable 1 summarizes the results of proximate and ultimate anal- listed in Table 2. The major oxides in these coals are Al203yses. The moisture content of the coal samples is low, ranging be- 77.41%) Cao(1. 10-43.34%) Fe203(6,46-12.80%),K0(1tween 0.94% and 149% the ash yield form coal is considered one 5.96%) Mgo(2.50-33. 32%)and Na20 (0.04-2.19%)of the main characteristics of coal in this Galandrud mine, which Coefficients of correlation between major elements of theis mainly in the form of gray, compact particles and varies from Galandrud coal are provided in Table 3. Although, the6.4% to 12.73% Its high content can be associated with the environ- associations may vary by coal type, a correlation analysiselementment prevailing at the time of the formation of this coal. The coal demonstrate general trends. Statically, a low positive correlationformed in this marshy environment has a high ash yield due to pol- (at the 0.99% confidence level )between the element and the ashlution with clastic material [14). In general, Galandrud coal has yield has only been established for K(r-0.30)and the other majormeltable ash, because of its high content of ferroxide, calcium elements(Al, Fe, Ca, Mg and Na) show no correlation. Elementsand magnesium(40-60%)[ 171that do not correlate with ash yields probably have different modesThe amount of volatile matter in an air-dried state is very high of occurrence in the coal studied.(3332-37.45%)which indicates the fact that they belong to a bitu- Table 3 shows that Fe, Na and Ca concentrations in the Galand-minous B coal group which has high volatile matter( 31%) accord rud coal are higher than those of the other major elements(Al, King to an astM(1991)classification [20]: the calorific value of and Mg): this observation seems to be mainly related to the CaGalandrud coal is 7430-8880 kcal/kg.and Fe bearing minerals. the concentration of Fe in the coal sam-ples shows positive correlation with K(r-0.56), Mg(= 0.52)4. 2. Mineralogyand Na(r=0.75), which is in agreement with the presence of clayminerals. in the coal studied the highest correlation is between alExamination of polished sections of the coal showed that and Na elements (r=0.93). The content of these elements in theGalandrud coal contains mostly dolomite(90%), quartz, shaler- coal studied are probably controlled by an abundance of organicite, galena, pyrite and clay minerals such as kaolinite. The carbon- matter( macerals).ate minerals are commonly syngenetic or rarely epigenetic inorigin. The epigenetic carbonates resulted from the carbonate bed- 4.4. Models of trace elements occurrence and concentrationrock geology occurring as cleat-filling as in the Galandrud bitumi-nous coal. the high carbonate content of this coal is a reflection of aTrace elements are defined as elements present in coal indeposition affected by paleogeology, since the coal developed in a amounts of less than 1 per cent of the coal weight and are reportedterrestrial environment on top of an unconformity of eroded lime- in part per million(x10-6)[7. The concentration of 47 trace andstone and dolomitic rocks 11, 16].Concentrations of major elements in coal samples of the Galandrud region(%)Results of proximate and ultimate analyses of Galandrud coal from central Alborz(%,Sample no. Al203 CaoFe 0 Ko Mgo450043.3461280094102131491051.1611189483170Volatile matter35933712333233.533415374535258.12Fixed carbon518551475258578855.59533353.7877411.108541.651103027中国煤化工CNMHFig.. Photomicrographs of minerals in galandrud coal: (a)sphalerite(b)galena(c)fracture-filling pyrite and (d) pyrite with framboid textureL Ardebil et al/Intemational Joumal of Mining Science and Technolagy 22(2012)101-106Table 3Pearson correlation coefficients (r) between major elements, ash and fixed carbon content of Galandrud coalFixed carbonCaoG0Fixed carbon085750080.110060809308Correlation is significant at the 0.05 level.Correlation is significant at the 0.01 levelrare earth elements(REE) have been determined (see Tabletheir affinities with organic and inorganic matter (Table 5).Thelthough the galandrud coal samples proved to be enrichedconcentration of arsenic, which is one of the most important HAPsost of these elements, in this study, eighteen trace elements in in coal, is from 19.8 x 10- to 31 x 10-6 and falls within the rangeoal, ie As, B, Ba. Be. Cd. Co, Cr, Cu, Hg. Mo, Mn Ni, Pb, Sb. Se, of most types of iranian and world coal (Table 4). Arsenic in theTh, U V and Zn were evaluated. The range of these trace elements Galandrud coal shows no correlation with ash yields but is posicoal samples studied are compared with the range of both Ira- tively correlated with Hg(r=0.81). U(r=0.87). Ca (r-0.84)andnian and world wide types of coal (7. 24].Fe(r-0.96) In these types of coal, there is evidence for an affinityIn Table 4, the results of our analyses of coal samples show sig- of organic matter with As and it is thought that As may be relatednificant amounts of Co(up to 51.3 x 10-) Cr(up to 65.5 x 10-6). to the Fe-As-oxide [27 and some minerals such as pyriteNi(up to 72. x 10-) Pb(for three samples, up to 88. x 10-6), HAPs and their contents fall within the range of most types ofTh(up to 11.9 x 10-6)and Mn (for two samples, up to 409 x world coal and show no correlation with ash yield. among these10). The higherlements cadmium is correl1438.2 x 10-)and Ba(up to 1172 x 10-)are associated with Be (r-0.82). Al(r=0.81), and Na(r-0.86). It appears that Cdanmostly used as an indicator of the depositional environment of coal with 54. 40 x 1086-248.20 x 10-6 concentration falls within thein our case study 17. 25). B can be a useful indicator for paleosalin- range of most types of iranian and world coal. this element in mostity of coal depositional conditions. Galandrud coal is enriched in v coal can be associated with sphalerite and pyrite [3, 17]. Beryllium(245.5 x 10-6-520 x 10-6). Co(513 x 106-110. x 10-6) Cr is reported to be associated with clay 28, 29).However, some stud-(65.5 10-6-194.2 x 10-) Cu (59.2 x 10--205 8 x 10-)and ies show that Be has a strong affinity for organic matter 8 .TheNi(72.9 x 10-6-1092x 10-) compared with the range for most concentration of Ni in Galandrud coal samples is higher than thatIranian and world coal (Table 4). The result of the studies by Yudo- of both Iranian (1.9 x 106-58. x 10-)and world coalvich(1972)on the geochemistry of coal showed that bituminous (0.5 x 10-6-50 x 10 6) This element is the only element that iscoal is of the vanadium type with high concentrations of V, Ti, positively correlated with ash yield (r-0.91). the mn content isNi, Co, Cu and some other trace elements [26]. Thorium is associ- between 156 6x 10-6 and 532 x 10-6. Most of the Mn in coalated with minerals in coal and appears to be also associated with especially in bituminous coal, occurs in solid solutions in carbonatemonazite which is an accessory mineral in coal and with minor minerals [7, 301. In the galandrud coal, Mn is correlated withamounts in xenotime, zircon and some clays [6(r-0.90)and is possibly related to organic matter.Pearson,'s correlation coefficients for element concentrations the Pb content ranges from 45. 1 x 10- to 147.7 x 10-6 whichwith and ash content may provide preliminary information for is a higher range for both other Iranian and world types of coalTable 4Trace element concentrations of Galandrud coal and comparison to the ranges for world coal and Iranian coal [7, 24](x10ElementWorld coal Iranian coal04313056.301108075.6010100GQMM丽732075.50494.107290734088.70113202-8043-978中国煤化工100.18-3.15120022-21.1CNMHGI245.503210017-21463.20999815-553L Ardebili et aL/ Intemational Joumal of Mining Science and Technology 22(2012)101-106Table 5Pearson correlation coefficients (r) between trace elements and ash content of Galandrud coalSb Se Th U V0620851a.10=023-0720.53-043-063025-0248027-006006-055-0450.21020-022-0.130260661Ni0710110.36021-035033030-031-018005Pb-0750.15039049-032-0640870990530010.16-033-0.121se071-023-045030-009-009-054-022071-025-0.52-042-0.0046-001-052-029004U078·005040059034014-060-0330904-033-0.75039-0620481v-0.78-037007-034024047083·029Zn017-018-04087089°052001050016047001021089016-038-02105g0.82-03707809079048-026031048009-045043084048-012-0750510.691Ash-081045066-0.32-035001013-039-033025a91a-037-067015-042059-002-0591Correlation is significant at the 0.05 level.Lead occurs almost exclusively as galena(Pbs)[31 and other Pb- rence in the coal studied. the amounts of al and na elements arebearing sulfides and possibly in pyrite as well [ 3]. In coal samples,bably controlled by the abundance of organic matterhis trace element shows positive correlation with Mo(r-0.91).(macerals).The studies reveal that Molybdenum in coal mostly occurs with orhe amounts of trace elements(As, Cd. Hg, sb, Zn, Se, Be and wganic matter and or can be related to sulfide minerals 8, 23. The in galandrud coal are low compared to both Iranian and worlranium content of Galandrud coal is low(1.2 x 10-6-4.8 x types of coal. Most of the trace elements(As, Cd, Co, Cr, Ca, Hg.10 compared to most of the coal in the world(0.5 x 10-6- Mn, Pb, Sb, Se, Zn, B, Ba, Be, Mn, Th, U and V) are not correlated10×106) and iranian coal(2.2×10646×106)twith ash yields, suggesting an organic association and only Ni isThe correlation between ash and U content indicates that U has positively correlated with the ash content (r-0, 90)indicating anan affinity for organic matter. However, it is highly correlated with affinity for inorganic matter. the concentration of this elementFe(r-0.95). As(r-0.87)and Mn (r=0.9)and can be associated (>72.90 x 10 )in the samples studied is higher than that of bothwith accessory minerals such as zircon and silicate minerals [8, 32). Iranian and world types of coalAs can be seen in Table 4. the th content is correlated with mgBoron content in the coal studied measured high( 1438 x 100.92), suggesting an association with clay minerals and mona- 3931. 2 x 10-) which indicates that this coal was affected byzite which is an accessory mineral in coal 6 Selenium content in water due to their deposition. Vanadium, Cr, Co, Cu and Ni in coalGalandrud coal samples is in the range of >0.05 x 10-6-0.94 x samples of Galandrud are also abundant, which indicates that10 6 which is lower than for other Iranian coal (0.75 x 10-6- these are v-types of coal.4 x 10-)and is within the range for that of most types of worldcoal(0.2 x 10-6-10 x 10-6)17 Se is not correlated with ash yield.but shows organic association, as inferred by Glukoter et al. (1977)Acknowledgmentsand Finkelman 128,31 However, Swiane [7 states that Se occurswith sulfide minerals in coal mainly pyrite[8].This research was supported by the iranian Institute for Geological Surveys and Mineral Exploration. The authors thank Mr. Koreieorganization manager of the mineralogy, petrology and geochem-5 Conclusionsistry laboratories. We also acknowledge Mr Ramezani for his helpin collecting coal samples in a Galandrud mine.The study of geochemistry of Galandrud coal indicates that thiscoal, of the upper Triassic-lower Jurassic eras, is bituminous coal Referenceswith high volatile matter(33%), deposited into the Shemshak for-mation, Geological settings have played key roles in determinig theSmith GC1“als in this coal consist mainly of dolomite(90%)and some other [3] Karayigit Al. Cayer RA Queral X Onacak T. Contents of major and traceminerals(i. e, quartz, sphalerite, pyrite. galena and clay mineralsfeed coals from Turkish coal-fred power plants. Int J coalPyrite in Galandrud coal is rare, has framboid texture(syngenetic00044;16984form)or is of a fracture-filling(i.e. epigenetic)form.Fe Na and Ca concentrations in galandrud coal are higher thanonmental quality and health.those of the other major elements(al, K and Mg): this observationseems to be mainly related to the Ca and Fe bearing minerals. The中国煤化工 sect of trace element inconcentration of the major elements (i.e Al, Fe. Mg Na and ca)in 16I iemour coal samples did not show correlation with ash yield and hasCNMHGIorS. Environmental aspectsonly been established for K(r-0.30). Elements which are not cor-cademic publishingelated with ash yields probably have different modes of occur. [71 Swine DL. Trace elements in coal. London: Butterworths: 1990.L Ardebll et aL/Intemarional Joumal of Mining Science and Technology 22(2012)101-10618) GOrdal G Geof acts of burming coal beds and waste banks. [21] Spear DA Zheng Y Geochemistry and origin of elements in some UK coals. Int Jce elements in Can coal(Miocene) Canakkale, [20) Oslanloo M Handbook of coal enginmir-Kabir(Tehran poly Technical)University prTehran: 1999-2上19-24vic A Inorganic constituents in coal Kem Ind 2006: 55: 65-77[221 Spear DA, Manazanares-Papayanopoulos L Booth CA The distributionI Gentzis T, Goodarzi F Selected elements and radionuclides in themal coalsorigin of trace elements in a UK coal: the importance of pyrite[12] Korkmaz s,3] Queral X Whateley MKG, Fernandez- Turiel Jl, Tuncali E. Geological controls onthe Jurassic coals in the eastern Taurus ofthe Beypazan lignite, Central Anatolia.[13] Mann U, Korkmaz S, Borehman C]. Hertle M. Radke M. wilkes H. Regional [24 Shojaei SV. Aftabi A Kazraninejad Res and claystones from the Eastern Penrides,h conference on Geology of Iran. 2007. p. 728-735 I In Persian[251 Swiane D] Why trace elements are important. J Fuel Process Technol 2000: 65-[14] Thomas L Handbook of practical coal geology. Chichester: John Wiley and[26 Yazdi M, Shiravani AE Geochemical properties of coals in the Lushan coal field[151 Bragin YN, Golubev SA Polyanskiy BV. Palo- geography of major accumulationof Iran. Int J Coal Geol 2004: 60:73-9.981; 16: 50-9 Publishedoal deposits in Iran. Lithol Mineral Resour [271 Belkin HE. Zheng B Finkelman RB GeochemistryConsultants Bureau. New Yoκk.UsA」16tal geochemistry, USA geoiogical survey open-file Report 97-496logical Surveyon of lran press: 1994[28 Finkelman RB. The use of modes of occ[17] Goodarzi F. Sanei H, Stasiuk LD, Bagheri-Sadeghi H, Reyes J. A preliminaryamdu191124rudy of mineralogy and geochemistry of four coal samples from northem [29] Zhuang X Querol x Zheng R Xu w, Alestuey A Lopez-Soler A Plana F.shui mining district,[18] Zamani Z. Srudy of geochemistrypanic petrography andh China. Int J Coal Geol 2000: 45: 21-3rocks: a geochemicagion( Central Elburz Master ofhesis, 1999: Tehran University ( In31 Finkelman: Review Int I Coal Geal 2003:56: 203.occurrence of potentially hazardous elements in coal:5- 765 in Persang of the 3th conference on Ceology. Shiraz (iran),199%. 132] Searoukum, edain Bagher- sadegh Mi per ologyk and evidence forRegion, Northem Iran. Int J Coal Geo! 2006: 67: 249-58中国煤化工CNMHG

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