GEOLOGICA BALCANICA, 30. 3-4, Sofia, Febr. 2001, p. 77-88
Chalcophile elements in some Bulgarian coals
Jordan Kortenski, Anton Sotirov
University of Mining and Geology "Sv. Ivan Rilski", Sofia, 1100, Bulgaria. (submitted: 24.06.1999; accepted for publication: 28.06.1999; revised version received 23.06.2000)
11:. KopTeHCKH, A. CoTHpos- XaAKOr/iUAbHble 3AeMeHmbl Abstract. The occurrence and distribution of Cu, Zn, As, B HeKomopblX 6oAzapcKux yzARX . .[Vrll npHCYTCTBHll Cu, Mo, Ag, Sn and Pb was investigated in coals of various Zn, As, Mo, Ag, Sn H Pb Hccne.uosaHbT yrnH HJ TpHHa.u rank (ranging from lignite to anthracite) from thirteen uaTH 6onrapcKHX 6acceiiHoB c paJHOH cTeneHbTO yrne coal basins in Bulgaria. The concentrations of almost all QJHKaUHH. Co.uep)l(aHHll 6oJJblllHHCTBa H3 :meMeHTOB B elements in the coal ash and bulk coal samples from the 30JJe yrneit nepHHKCKOTO, CaMOKOBCKOTO, COQJHHCKOTO Pernik, Samokov and Sofia Basins are the highest and 6acceHHOB MaKCHMaJJbHbTe H 6onee BHCOI Kortenski, J., Sotirov, A. 2000. Chalcophile elements in some Bulgarian coals. - Geologica Bale., 30, 3-4; 77-88 Key words: chalcophile elements; coal; Bulgaria 77 Introduction Sampling and experimental The occurrence and distribution of seven chal Digestion and analysis. cophile elements - Cu, Zn, As, Mo, Ag, Sn and A set of 718 core and channel samples of Pb in coal and coal shale from 13 Bulgarian coal and coaly shale were investigated. The coal basins and deposits are investigated (Fig. samples were ashed at 800 °C. The ash samples 1). The coal deposits investigated were: a) Lig were analyzed by Instrumental Neutron Activa nite from eight Neogene deposits were studied tion Analysis (INAA) and Inductively Coupled - Maritza-West, Stanyantzi, Belibreg, Sofia, Plasma Emission Spectrometry (ICP-AES). Karlovo, Samokov, Kyustendil, Oranovo and The results (Tables 1-5) were processed statisti Gabrovitza. b) The subbituminous coal from cally and the correlation coefficients between the Paleogene Pernik Basin. c) The bituminous the concentrations of the elements in the coal coal from Eocene Suhostrel and Cenomanian ash and the respective ash contents were deter Balkan Basins. d) The anthracite from the mined (Table 6). Svoge Carboniferrous Basin. The geochemical Determination of the affinities. peculiarities and distribution of these elements, Trace elements, which show a negative cor with the exemption of Sn, in Bulgarian coal relation coefficient with the ash content and from other basins and deposits were studied by their concentration decreases with the increas EcKeHa3H (1974), Eskenazy (1994, 1995) and ing of the ash content (Fig. 2) are determined as EcKeHa3H, MHH"'eBa (1986). elements with a higher organic affinity. Trace 0 M A N I A BUCK SEA OS ml2 4Skm Fig. 1. Location of the coal basins sampled for the present study: a - lignite; b - subbituminous coal; c - bituminous coal; d - anthracite; 1 - Maritza West; 2 - Stanyantzy; 3 - Belibreg; 4 - Sofia; 5 - Karlovo; 6 - Samokov; 7 -Gabrovitza; 8 - Kyustendil; 9 - Oranovo; 10- Pernik; II - Suhostrel; 12- Balkan; 13- Svoge 78 which are determined as elements with an inter mediate (mixed) affinity, have correlation coef ficients (negative or positive), whose values are not statistically reliable. In this case, the ele ment's concentration is saved almost constant with the change of the ash content (Fig. 4). Sometimes the correlation between ash and trace element contents is not enough to ensure the affinity, because some sulfides could be en riched in the ash-poor coals. The mineral form of the chalcophile elements is connected with :J) the sulfides. Kortenski, Kostova (1996) report 25 1-sn that the pyrite from Bulgarian coals very often E 2:20 associated with clay minerals in the ash-rich c"" 15 coals. The pyrite content also increases with the !! a 10 growing of the ash content. Therefore, the af u finity, determined by the correlation between ash and element contents are enough correctly. 20 00 100 Results and discussion Fig. 2. Plot of chalcophile elements concentrations in ash versus ash content in some studied basins. Copper 1 - Maritza West; 4 - Sofia; 6 - Samokov; 9 - Oranovo; 10 - Pernik Coal ash from the Sofia, Kyustendil, Samokov and Pernik basins exhibit Cu concentration elements, which show a positive correlation co (Table 1). The Cu content exceeds the Clarke efficient with the ash content, are determined by IO.u.osH\.f et al. ( 1985) from 5 to 7.5 times. as elements with an inorganic affinity. The ele The Cu concentration in the ash from the Kar ment concentration increases with the growing lovo, Oranovo and Belibreg lignite exceeds of the ash content (Fig. 3). Trace elements, nearly 2 times the same Clarke (Table 1) . The 1«l 1«l 120 120 ~m +.---~•~------~•~--_.. a.K1oo [100 c 00 12-/G a. 80 13-QJ ·----~-...... ------i·l--- -· ~ ro ~ 60 8 «l c 8 40 20 20 1~~ k-k----~·~------·._--~. o +-----~----.-----.---~----~ 0 20 00 100 0 +-----.---~----~----.----. 0 20 40 60 BO 100 2 3-lq ..____ _.• ..__------"~·~--...... E 1.5 a. c. -- 7-Sn ~ 1 ------~ E 0 u 0.5 o+-----~----~----~----~--~ 0 20 40 60 80 100 o+-----~--~.----,----~----~ 0 20 40 60 80 100 Fig. 3. Plot of chalcophile elements concentrations in ash Fig. 4. Plot of chalcophile elements concentrations in ash versus ash content in some studied basins. versus ash content in some studied basins. 3 - Belibreg; 5 - Karlovo; 7 -Gabrovitza; 9 - Oranovo; 2 - Stanyantzy; 3 -Belibreg; 7 -Gabrovitza; 12 - Balkan; 11 - Suhostrel; 13 - Svoge 13 - Svoge 79 Table 1 Average content of the elements in the coal ash No Basins Number Cu Zn As Mo Ag Sn Pb of the ppm ppm ppm ppm ppm ppm ppm samples I Maritza-West 38 67 58 126 20 4.2 24 31 2 Stanyantzi 38 24 119 110 5.7 ND 21 71 3 Belibreg 39 86 51 172 1.7 1.7 l.l 20 4 Sofia 59 385 215 60 77 2.7 5.8 75 5 Karlovo 23 106 87 44 39 2.9 6.2 54 6 Samokov 31 340 424 150 11 1.9 2.4 116 7 Gabrovitza 40 40 51 125 7 0.8 1.2 52 8 Kyustendil 39 377 113 3.9 9 1.0 13 23 9 Ora novo 98 95 53 413 33 3.4 1.0 48 10 Pernik 35 237 301 339 19 0.3 2.7 101 11 Suhostrel 17 53 95 Ill 2.9 2.1 17 38 12 Balkan 26 52 91 91 17 1.5 8.4 25 13 Svoge 90 87 162 88 26 2.2 4.6 62 Clarke for lignite and subbituminous coal ash1 48 100 60 13 4.1 53 Clarke for bituminous and anthracite coal ash1 80 150 90 25 2.5 7.5 170 I - by IO~oBH'f et al. (1985); ND - no data. Table 2 Average content of the elements in the coal No Basins Number Cu Zn As Mo Ag Sn Pb of the ppm ppm ppm ppm ppm ppm ppm samples I Maritza-West 38 20 17 38 6.0 1.3 7.2 10 2 Stanyantzi 38 7.5 36 33 1.7 ND 6.3 22 3 Belibreg 39 26 15 52 0.5 0.5 0.3 6 4 Sofia 59 116 64 18 22 0.8 1.7 22 5 Karlovo 23 22 16 8.3 6.7 0.7 1.2 14 6 Samokov 31 102 127 45 3.3 0.6 0.7 35 7 Gabrovitza 40 12 15 37 2.1 0.2 0.4 16 8 Kyustendil 39 68 20 0.7 1.6 0.2 2.4 4.7 9 Oranovo 98 8.4 4.7 37 2.9 0.3 0.1 4.2 10 Pernik 35 71 90 102 5.9 0.1 0.8 30 II Suhostrel 17 16 28 33 0.9 0.6 5.1 II 12 Balkan 26 16 27 27 5.2 0.5 2.5 7.6 13 Svoge 90 26 49 26 7.8 0.7 1.4 18 Clarke for lignite and subbituminous coals1 7.5 18 14 2.4 0.3 25 Clarke for bituminous and anthracite coals1 18.5 22 20 3 0.4 1 25 Range for most coals1 0.5-50 5-300 0.5-80 0.1-10 0.02-2 1-10 2-80 1- by IO~OBH'I et at (1985); 2- by S w a i n e (1990); ND - no data. 80 coal ash from the Stanyantzi, Gabrovitza, Su other basins (Table 3), while the Cu content in hostrel and Balkan basins contains a smaller the coal of all · investigated Bulgarian basins is amount of Cu than the Clarke. higher than nearly all data for other coal basins The concentrations of Cu in the coal from (Table 4). these basins are also high, with the excepting of The concentration of Cu significantly ex the comparison with the Clarke by lO.LJ.OBHI.f et ceeds the Clarke by Turekian, Wedepohl (196 1) al. (1985), it is a little bit lower only in the Su in the coaly shale ashes from the Kyustendil, hostrel and Balkan bituminous coal (Table 2). Belibreg, Sofia, Samokov, Svoge and Pernik ba The Cu contents in the lignite from the Sofia, sins (Table 5). Kyustendil, Oranovo, Samokov basins and sub The organic affinity of Cu is high in the coal bituminous coal from Pernik Basin are higher from the Maritza-West, Karlovo, Oranovo and than the range for most coals by S w a i n e Samokov basins. Their coefficients of correla (1990). tion between elements and the ash vary from The coal ashes from the Sofia, Kyustendil, -0.51 to -0.82 (Table 6). For prevailing organ Samokov and Pernik basins have higher con ic affinity of Cu see M H H l.f e s, E c K e H a 3 H centrations of Cu than the ashes from most (1963, 1965), P i p i r i n g o s (J 966), IO .Ll. o - Table 3 Average content of the elements in the coal ash from different basins Ag ppm Sn ppm Pb ppm Refe· Country, basin Rank Cu ppm Zn ppm As ppm Moppm I rences Austria L 40 100 68 7 0.4 10 6 l Hungary, Northeas-tern Basin L 110 100 150 10 0.3 8 50-60 2 Belarus s 22 NO NO NO NO NO 35 3 Germany L 90 NO 445 NO NO NO 210 4 Canada, Saskat-chewan L 37.3 9.0 11.4 15.0 NO NO 400 5 India, East Bokaro B 20 -180 NO NO 10 - 20 NO 10 - 20 20 -110 6 Bulgaria, Maritza - East L 162 488 50 17 0.1 7 6.5 7.1 7 England, Eggborough B 248 140 NO NO NO NO 120 8 England, Barnsley B 42 52 NO NO NO NO 17 9 Bulgaria, Pirin S - B 126-335 225-305 181-408 57-60 NO 9.5-ll 76-129 10 Greece, Drama L 17.2-27.8 56-93 79-366 40-98 1.6-2.3 < 10 9.1-14.7 ll Rank: L - lignite; S - subbituminous coal; B - bituminous coal. 1 - Brandenstein et al. (1960); 2 - Veto (1973); 3- EopnoH (1973); 4 - Sontag (1967); S - Beaton et al., (1991); 6 - Pareek and Bardhan ( 1985); 7 - Mim'leB, EcKeHaJH ( 1972); 8 - Spears and Martinez - Tarazona (1993); 9 - Spears and Amin (1981); 10- EcKeHaJH, 4y6pHeB (1984); II - Filippidis et at. (1996); NO -no data. Table 4 Average content of the elements in the coal from different basins Country, basin I Rank I Cu ppm I Zn ppm I As ppm Moppm Pbppm References USA, North Dakota L 5.8 2.7 3.4 1.2 3.0 l Australia B IS 25 3.0 1.5 10 2 Canada: Tulameen B NO 20 4 3 ND 3 Hat Creek s 14-80 12-83 4-30 1.3-8.8 NO 4 Canmore SA 19 5.6-8.7 0.44 0.6-1.3 ND s British Columbia B 7-33 10-74 0.5-80 0.3-3.2 2-15 6 Spain, Teruel s 11.2 36.4 16.4 3.9 12.1 7 Bulgaria, Pirin S-B 13-18 43 -ll7 12-59 8.6-9.4 5-20 8 Greece, Drama L 17-28 44-131 76-433 40-90 < 10 9 Fuxin, China B 8-13.8 22-61.3 2.6-7.1 2.2-7.5 5.4-15.4 10 Beypazari, Turkey L 2-92 6-227 32-148 3-13 2-34 11 Rank: L - lignite; S - subbituminous coal; B - bituminous coal; SA - semianthracite. l - Gluskoter et al. (1977); 2- Swaine (1983); 3- Beaton et at. (1991); 4- Goodarzi and Vander Flier - Keller (1988); 5 - Goodarzi and Cameron (1987); 6 - Grieve and Goodarzi (1993); 7 - Querol et at. ( 1992); 8 - EcKeHaJH, qy6pHeB (1984); 9 - Filippidis et a!. (1996); 10 - Querol eta!. (l997a); ll - Querol et at. (l997b); NO - no data. II Geologica Balcanica, 3-4/2000 81 Table 5 Average content of the element in the coal shale ashes No Basins Number Cu Zn As Mo Ag Sn Pb of the ppm ppm ppm ppm ppm ppm ppm samples 1 Maritza-West 9 3 14 13 2.1 1.6 19 9 2 Stanyantzi 10 18 112 73 4.0 ND 47 65 3 Belibreg 8 129 72 125 1.4 1.6 2 30 4 Sofia 19 280 280 1.2 15 0.7 8 50 5 Karlovo 9 45 76 4 5.5 3.7 8 44 6 Samokov 10 171 262 84 9.0 1.0 5 59 7 Gabrovitza 8 44 79 150 5.4 0.5 1.1 91 8 Kyustendil 9 1840 368 l.l 1.8 0.2 55 37 9 Oranovo 22 16 53 135 33 1.0 5 25 10 Pernik 9 84 253 68 3.4 0.2 3 35 11 Suhostrel 8 41 231 69 5.6 1.0 25 31 12 Balkan 7 28 130 4 10 0.5 12 25 13 Svoge 21 79 55 124 12 3.0 13 37 Clarke for shales1 45 95 13 2.6 0.07 6 20 1- byTurekian and Wedepohl (1961). Table 6 Correlation coefficients between the element concentration in the coal ash and the ash content No Basins Zn-Ash Mo-Ash Pb-Ash 1 Maritza-West -0.82 -0.71 -0.85 -0.82 -0.56 -0.31 -0.68 2 Stanyantzi -0.21 -0.05 -0.29 -0.32 +0.85 -0.09 3 Belibreg +0.43 +0.39 -0.31 +0.29 +0.05 +0.47 +0.38 4 Sofia -0.19 +0.40 -0.71 -0.62 -0.54 +0.41 -0.32 5 Karlovo -0.51 -0.31 -0.82 -0.75 +0.46 +0.53 -0.37 6 Samokov -0.51 -0.47 -0.48 -0.33 -0.46 +0.41 -0.49 7 Gabrovitza +0.19 +0.42 +0.38 -0.31 -0.38 +0.05 +0.41 8 Kyustendil +0.82 +0.80 -0.65 -0.77 -0.79 +0.80 +0.46 9 Oranovo -0.50 - 0.25 - 0.48 -0.38 -0.48 +0.30 -0.25 10 Pernik -0.30 -0.43 -0.47 -0.76 -0.31 +0.42 -0.50 11 Suhostrel -0.29 +0.51 - 0.34 +0.34 +0.06 +0.49 -0.23 12 Balkan -0.49 +0.33 -0.33 -0.48 -0.66 +0.75 -0.03 13 Svoge -0.09 -0.53 +0.38 -0.50 -0.02 +0.71 -0.31 B H q et al. (1985). According to S w a i n e the number· of molecules that connects one (1975, 1983) and Parr e k, Bard han (1985), copper ion increases too. As a result of this, Cu forms organic complexes, and E s k e n a z y lower amount of Cu is accumulated in the vul (1995, 1996) suggests a high typomorphy for foacide. For this element M a H c K a Sl, ,ZJ; p o 3 this element for·many the other Bulgarian coals .no s a (1964) report that optimal condition for with predominance of its organic form. Copper its accumulating in metalorganic composition in the coal from Stanyantzy, Sofia, Gabrovitza, exists when pH is from 3 to 6. This explains the Svoge, Suhostrel, Balkan and Pernik Basins has increased organic affinity of Cu in the Maritza nearly the same organic and inorganic affinity. West Basin (pH from 4.5 to 5.5) (Korte n ski, Similar Cu affinity was described by G 1 u s k o 1992) and its decrease in the lignite from the t e r et al. (1977), Kojima, Fur us a w a Sofia (pH from 4 to 7) and especially from Be (1986), Q u e r o 1 et al (1997a) and etc. The libreg (pH from 6 to 8) (K o r t e n s k i, 1992). inorganic affinity of Cu prevails in the coal from the Kyustendil and Belibreg basins. Simi Zinc lar affinity of Cu was deduced by Z u b o v i c (1966), S w a i n e (1990), E c K e H a 3 H, M H H The zinc content in the coal and the coal ashes q e sa (1994), Que r o 1 et al. (1997b). from the Samokov, Pernik and Sofia basins is The investigations of S c h n i t z e r (1971) more than two times higher than the Clarke by prove, that low values of pH, between 3 and 5, lO .noB H q et al. (1985) and higher, to range one molecule of vulfoacide connects with one for most coals by S w a i n e (1990) (Tables 1 copper ion. When the values of pH increase, and 2). The amount of Zn in the above men- 82 tioned coal is higher than its content in many where the As concentration is 13.7 times high other basins (Tables 3 and 4). Close to the Clar er. The lignite from Sofia, Karlovo and Kyuste ke is the element concentration in the coal and ndil makes an exception. The As content in the the ashes from Stanyantzi, Suhostrel and Svoge, ashes of the bituminous coal and anthracite is while the amount of Zn is significantly under nearly to the Clarke (Table 1). For comparison the Clarke in the Maritza-West, Oranovo, Beli the As amount in the most of the investigated ba breg and Gabrovitza lignite. The content of Zn sins is higher except for some German coal and in Oranovo and Gabrovitza lignite is lower than the coal from the Pirin Basin (Tables 3 and 4). that in the basins in Table 3 and 4, except for The concentration of this element in the coal the lignite from North Dakota. shale ash is high. It is significantly above the The concentration of Zn in the coal shale Clarke except for these from Sofia, Karlovo ashes exceeds many times the Clarke for the and Kyustendil basins (Table 5). Arsenic shows sedimentary rocks (Table 5). Maritza-West, Be high organic affinity in the most types of inves libreg, Karlovo, Svoge and Gabrovitza offer an tigated coal. Only in the lignite from Gabrovi exception to this. Probably the amount of Zn tza and anthracites from Svoge a positive cor was insufficient in the source areas of these ba relation of As with the ash content is observed sins, because the zinc concentration is low in (Table 6). Based of this fact it is supposed that the coal and in the coal shale. As in these coal has a higher inorganic affinity. The Zn has very high organic affinity in the C M u p H o B ( 1969), G o o d a r z i ( 1987), G lignite from Maritza-West and in the anthra o o d a r z i, V a n d e r F 1 i e r - K e I I e r cites from Svoge. A high organic affinity of the (1988) report data for higher organic affinity of Zn is established also and in the coal from As, while Harvey et al. (1973), Kuhn et al. Samokov, Pernik, Oranovo and Karlovo in (1980), K o y u m a, F u r u s a w a (1986), Q u which the correlation coefficient with the ash is e r o I et al. (1997a) report the opposite opin also negative (Table 6). The organic and inor ion. A lot of authors think, that the As has a ganic affinity of this element is equal for the good correlation with the pyrite (M u H q e B, E Stanyantzi lignite. For the coal from the other c Ke H a 3 u, 1963; G 1 us k o t e r et al, 1977; S basins, the inorganic affinity of Zn prevails. wain e, 1990; Que r o 1 et al. 1992, 1997a). Data for the prevailing organic affinity of Zn IO .u o B u q et al (1985) accept that the high As are published by M u H q e o, E c K e H a 3 u, concentration is specific for the coal with high EcKeHa3u(l963, 1965, 1972), CMnpHOB ash content and in cases of presence of the hy (1966), Parr e k, Bard h a n (1985), S w a i drothermal mineralization and the low concen n e (1975, 1983), Q u e r o 1 et al. (1997a) and tration of As is the result of organic presence. for other Bulgarian coals E s k e n a z y (1995). Que r o I et al. (1997b) report for mixed affin p 0 )I( K 0 B a, l.q e p 6 a K (1956) report that ities. E s k e n a z y (1995) suggested that As is Zn org as humic complex is more unstable than linked mainly with the pyrite and partially with the same for Cu and Pb. It is probably the rea- the plant tissues and not finding arguments for son for the established higher inorganic affinity the presence of As-organic compounds. The ofZnbyMuHtieB, EcKeHa3u(1961, 1966), same author thinks that As is tipomorphic ele Z u b o vic et al (1961), Swaine (1990), E s k ment for a lot of the Bulgarian coal and that it e n a z y (1995), Q u e r o I et al. (1997b ), and Z u is concentrated mainly in the low-ash fractions b o v i c (1966) reported data for the full absence (E s k e n a z y, 1996). B e 1 k i n et al. (1997) of Zn , in US coal. 0 t t e (1953) and Que r o 1 report, that As continents are as high as 35,000 et al.(r992) accepts that the amount of Znorg and ppm in selected coal samples and the minera Zn mm. are commensurable. lised coals contain multiple As-bearing phases including arsenopyrite, As-bearing pyrite, ar Arsenic senic sulphide, Fe-As oxide, As-bearing K-Fe sulphate (jarosite?), and As-bearing iron phos The content of this element in almost all of the phate. However, the S amount and respectively coal with the exception of the Karlovo and Ky of the pyrite is not high in the great part of the ustendil lignite is higher than the Clarke by IO studied coal and As is established as a trace el .u o B u q et al. (1985) (Tables 1 and 2). The As ement only in the pyrite from Balkan and Svoge contents are mostly higher than the range for coal (Korte n ski, K o s to v a, 1996) and most coals by S w a i n e (1990). The As amount jarosite is established only in the Pernik and is the highest in the Oranovo and Pernik coal Balkan coal. Nevertheless, the cluster analysis (Table 2). The lowest rank coals have concen for chalcophile elements, maceral groups and tration of As 2 times more than the Clarke. This major minerals in the coal from the Balkan Ba specially refers to the coal from Oranovo Basin sin, shows a link between the As and Mo with 83 the vitrinite, and a negative correlation with the tions fixed as oxides and associated with clay pyrite. As a whole the As concentration of the minerals, heavy minerals or sulphides in the investigated coal is not high and probably it is Mequinenza coal. This was possible in the coal connected with the plant tissues. from Belibreg, when the environment was prob ably alkaline (K o r t e n s k i, 1992) and Mo Molybdenum shows inorganic affinity. The concentration of the Mo exceeds the Clar Silver ke from 1.5 to 5.9 times in the coal ash from Maritza-West, Oranovo, Pernik and especially The concentration of Ag is above the Clarke from Karlovo and Sofia (Table 1). The Mo con from 1.7 to 4.2 times in the coal ash from the centration is near to the Clarke in the Svoge Belibreg, Samokov, Karlovo, Sofia, Oranovo anthracites, but it is under the Clarke in the and Maritza-West Basins. It is near and under other studied coal and specially the coal from the Clarke for the rest of the basins studied in this Suhostrel and Belibreg basins (about 8 times). paper. In the Stanyantzi lignite Ag is not estab Probably the element shows mainly an inorgan lished and in the coal from Pernik the Ag concen ic affinity in the coal Suhostrel and Belibreg. tration is very low (Table 1). The content of Ag is It is explicable for the Belibreg basin, where above the Clarke in the coal from same basins the pH of the environment in the ancient peat and in the Svoge anthracites (Table 2). In Tables 3 bog there had been with a high value - 6.5 to 8 and 4 the data for the Ag amounts is limited and (K o r t e n s k i, 1992). The conditions had not with exception of the Drama lignite they are un been favourable for the creating of metalorgan der the Clarke. The Ag concentration in the coal ic compositions. At the Suhostrel peat bog, the shale ashes is significantly higher than the Clarke pH of the environment had varied from 3 to 4.5 for sedimentary rocks (Table 5). (K o r t e n s k i, K o s t o v a, 1996), i.e. in the The reference data for the organic and inor interval which is reported by M a H c K a H, .[( p ganic affinity of the Ag are limited. E c K e H a 3 H o 3 .n o B a (1964) as the optimal one for the (1974) defines the element as an element "orga connecting of the Mo with the functional nofil" or that the Ag has organic affinity. A pre groups of the organic acids. Probably the peat vailing organic affinity is accepted by C M H p H bog was supplied by low amounts of this ele o a (1969), M H H 1.1 e a, E c K e H a 3 H (1972). ment mainly as plant tissues. The clastic matter IO .n o B H 1.1 et al. (1985) considers that the Ag that contained Mo. Data for inorganic affinity concentrates in the coal with high ash content of Mo is reported by G I u s k o t e r et al. connecting itself with the sulphides or with the (1977), H a r v e y et al. (1983) and Q u e r o organic matter. For the most Bulgarian coal in I eta!. (1992). Que r o 1 et al. (1997b) accept vestigated in the present paper, the correlation that the element is connected entirely with sul coefficients between the Ag concentration and phide minerals. the ash content are negative (Table 6) and Ag The Mo content both in the coal from the shows high organic affinity. Only the Karlovo above mentioned basins and in the Svoge an lignite established a positive correlation coeffi thracites are higher than the Clarke by IO .no a cient with the ash content for them (Table 6). In H 1.1 et al. (1985). It is higher than the range for the Belibreg, Suhostrel and Svoge coal the Ag most coals by S w a i n e ( 1990) (Table 2). The has an equal organic and inorganic affinity. values of concentrations of Mo are not high in the coal and their ashes from other basins in Tin Tables 3 and 4, except for the Pirin coal. The Mo concentration in the coal shale is above the The Sn concentration is significantly above the Clarke and Suhostrel, Belibreg and Maritza Clarke for the coal ashes from the Suhostrel, West making an exception (Table 5). Kyustendil, Stanyantzi and Maritza-West Ba The Mo shows high organic affinity in the sins (Table 1). The rest basins show a Sn con most types of investigated Bulgarian coal (with centration near the Clarke. Only in the lignite out these from Suhostrel and Belibreg), and it is and their ash from Oranovo, Belibreg and especially high in the coal from Maritza-West, Gabrovitza the Sn content is significantly under Pernik, Kyustendil and Karlovo. For such an the Clarke (Table 1, 2). The information for Sn affinity data are reported by 0 t t e ( 1953), M H about the basins in Table 3 is comparatively H 4 e B, E C K e H a 3 H (1961, 1963, 1965, 1972), high, but do not exceed the values of the above C M H pH o a (1969), E s ken a z y (1996), Q u mentioned four basins. For the Sn amount in e r o I et al. (1997a). Que r o 1 et al. (1996) the coal the tendency is the same and the ele ascertain the fact that Mo in alkaline condi- ment concentrations are in the interval of the 84 range for most coals by Swaine (1990) (Table the mineral solutions which have penetrated 2). The concentration of Sn in the coal shale through cracks and have accumulated epige ashes is significantly above the Clarke for the netic minerals in the bituminous coal and an sedimentary rocks in most of the basins. The thracites and 2) the presence of ground waters Belibreg and Gabrovitza coal shale only make which are the reason for the higher values of an exception (Table 5). pH of the environment in most of the peat bogs Many authors report data for the inorganic than the favourable one for the creation of the affinity of Sn and especially for the link be lead-organic compositions (3.5 according to tween the Sn and the sulphide minerals (Z u b o S c h n i t z e r, 1971 ). This underground feed v i c et al., 1961; M H H Y e B, E c K e H a 3 H, ing exerts influence on the organic affinity of 1961, 1963, 1965; I0 .li, 0 B H Y, lli a C T K e B H Y, Pb, too. The organic affinity is significantly 1966; C M H p H o B, 1969), and Q u e r o I et al. higher in the coal from Samokov, Pernik and (1997a,b) report for high alumosilicate affinity specially in Maritza-West. The organic affinity in coals from China and Turkey. Few publica of this element is predominant also in the coal tions report for the organic affinity of the Sn from the Sofia, Karlovo, Oranovo and Svoge (I d z i k o w s k i, T r z e b i a t o w s k i, 1960; Basins. IO .LI. o B H Y et al. (1985) assume that P i p i r i n go s, 1966). 0 t t e (1953) even marks the values of Pb which are near to the Clarke, an equal organic and inorganic affinity in Ger are the result of the presence of its organic man coal. The correlation coefficients with the form, and the values, which are significantly ash are positive for nearly all of the investigat above the Clarke, are result of the presence of ed coal, some of them having very high values the sulphide minerals. For the predominance of (Table 6). The coals from Maritza-West and the Pborg in some Bulgarian coal data is report partially from Gabrovitza make an exception. ed by M H H Y e B, E c K e H a 3 H (1972), E s The probably reason is the high amount of the kenazy (1995,1996). pyrite in the low-ash coal, but it is possible the A predominant inorganic affinity of the Pb is short interval of variation of pH - 4+5.5 (K o p established in the Belibreg, Gabrovitza and Ky Te H c K H, 1994) to appear the most favourable ustendil coal. It is natural, having in mind the one for the concentration of this element in the presence of the underground feeding and low organic matter and for the stabling of these alkaline environment in the ancient peat bogs compositions. The interval of variation of pH of Belibreg and Gabrovitza in the different stag for the other basins is much larger and this is es of their development. Harvey et al. (1983), the possible reason for the non-formation or W a r d (1980), S w a i n e ( 1990), B e a t o n et instability of the metalorganic compositions of al (1991), Que r o I et al. (1997a,b) etc. report the Sn. Sn probably has equal organic and inor for the inorganic affinity of the Pb, and for ganic affinity in lignite from Gabrovitza, simi some Bulgarian basins data is reported by E s - larly to the data reported by 0 t t e (1953). ken a z y (1995, 1996). The organic and inorganic affinity of the Pb is Lead equal for the coal from Stanyantzy, Suhostrel and Balkan Basins. 0 t t e (1953), Q u e r o I et al The concentration of Pb is not high in the coal (1992) reported data for similar affinity of Pb. and their ashes for the studied basins. Exclud ing the coal from Samokov and Pernik in which Distribution of the elements the concentration of Pb is two times above the Clarke, in other coal it is near and under the Clar Many authors have investigated the factors that ke and range for most coals (Tables 1 and 2). This determine the presence and the distribution of specially refers to the Belibreg, Oranovo and Ky the elements in the coal. These investigations ustendil lignite and the Balkan and Suhostrel Bi are summarised by IO .LI. o B H Y (1978), B o i1 - tuminous coal. The Pb concentration is lower T K e B H Y et al. (1983), S w a i n e (1990), from this for other basins (Tables 3 and 4). The Good a r z i, Swaine (1993), E s ken a coal from Maritza-East, Bamsley, Drama and z y (1996). North Dakota make an exception (Tables 3 and A considerable role for the presence and the 4). The Pb concentration is above the Clarke in distribution of the studied chalcophile elements the coal shale for all studied basins, except Mari in the basins studied in this paper have played tza-West (Table 5). the following factors: I) the content of the ele The possible reason for the lower concentra ments in the plant tissues forming the peat; tion of Pb in studied coal may be: 1) the low 2) the concentration of the elements in the concentration of this element in the rocks from rocks from the coastline; 3) the type and direc the coast line of the ancient peat bogs and in tion of feeding (surface and underground); 85 4) pH and Eh of the environment in the ancient The type of feeding influences also the pH of peat bog; 5) the degree of fracturing of the coal the environment in the ancient peat bogs. When seams and 6) the presence and composition of the environment is more alkaline, the most ele the mineral waters which precipitate infiltra ments do not fix as element-organic composi tional minerals into the fractures of the coal tions and this could be the reason probably for beds. the Belibreg lignite to have low concentrations B o ii T K e B n q et al. (1983) give extensive of these elements. In this case the As makes an for significant presence of Cu, Zn and Mo in exception. It probably is supplied through plant the plants - peatformers. The other interpreta tissues. This situation relates to the Stanyantzi tions' elements studied may form significant and Gabrovitza lignite also. The exclusively accumulations when the conditions of the envi high organic affinity of the elements probably is ronment (pH) are favourable. E s k e n a z y the result of the very narrow interval of pH of (1995) assumes that As is mainly associated the environment in the peat bog of the Maritza with sulphides not finding a proof for another West Basin. This interval is optimal for the cre presence of this element except in the plants. ation of the element-organic compositions re The above-said for the research of the Balkan ported by M a H c K a .s~, )]; p o 3 .no B a (1964). coal in which a correlation of the As with the The higher variation of the acidity during the vitrinite is ascertained, and negative correlation different stages of the peat bogs development coefficients with the pyrite, hydroxyl, carboxyl (specific for the other basins) are probably the and carbonyl groups, also gives the reason a cause for the comparatively lower organic af considerable accumulation of this element in finity of the elements. the plants to be assumed. The fracturing and the epigenetic mineraliza The metalogenic provinces of the basins are tion for the younger lignite basins have an insig very important for the distribution of the ele nificant meaning, because they have low devel ments (E s k e n a z y, 1996). The presence of oped seams. The seams in the Pernik, Svoge source land rocks that have sulphide mineral and Balkan Basins have many fractures. In the izations is important too. This specially refers Suhostrel coal the fracturing is low developed to the Samokov, Pernik and Sofia Basins that and the infiltrational mineralization is low too. have high concentrations of Cu, Zn, Pb and It may be also the reason for the low content of partially of As. These basins are situated near nearly all studied elements in this coal. In the the Plana, Lyulin and Vitosha plutons in which other three basins an epigenetic mineralization similar mineralizations are observed. Investiga is established. The composition of the solutions tions of the area distribution of Cu, Zn and Pb penetrating in the seams plays an important established maximum concentrations in the role there. Pyrite and partially siderite infiltra Northeast part of the Samokov Basin. This part tional mineralization is seen in the Pernik Basin is near to the Plana pluton. The coal from the and this is a reason for the high concentration Karlovo (situated in West-Sredna Gora) and of many elements studied in this paper. Quartz, the Kyustendil basins have high concentrations various carbonates and lower sulphide mineral of Cu (Table 1). izations are established in the Balkan and Svoge The type of source land determines the dep coal. May be this is also a reason for the lower osition of the elements. The surface waters that concentration of the investigated chalcophile bring clastic material also bring significant elements. However the Svoge anthracites show amount of elements from the rocks of the coast more sensible presence of Cu, Pb and Zn. These line. The underground waters related mainly to elements are established as occurrence in the carbonate rocks, are the source of the lowest infiltrational carbonates also (K o r t e n s k i, amount of chalcophile elements. The rocks 1992). Pb and Zn are absent in the same miner from the coast line of Sofia Basin are character als from the Balkan Basin (K o r t e n s k i, ised by very low concentrations of Pb, Zn, Mo, 1992). In result the concentration of these ele Sn in the Middle Triassic and the Jurassic lime ments there is lower than in the Svoge anthra stone from Northwest and West direction. It is cites (Table I). the reason for the low concentrations of these The option of IO .n o B n q (1978) that the elements in this part of the Sofia Basin and es degree of coalification influences the concen pecially during the stages of active under tration of elements in the coal is probably true, ground feeding. The rocks building the ancient but for equal other conditions, as in the investi coast line of the Belibreg Basin are similar, their gated coal similar tendency is not established. underground feeding is the cause for one of the On the contrary, there is not an element which lowest concentrations of the studied chalco content is highest in the bituminous coal of the phile elements there (Table 1). Suhostrel and Balkan Basins or the Svoge an- 86 thracites. Similar conclusion for the distribu Miner. und Petrogr. Mitt., 7, 3, 260-285. tion of Ni and Co is done by KopTeHCKH Eskenazy, G. 1994. Geochemistry of copper, zink and lead in Bulgarian coal deposits. - roo. CY, Feo/1. (1998). zeozp. ffjaK., 87 c. Eskenazy, G. 1995. Geochemistry of arsenic and antimo ny in Bulgarian coals. - Chem. Geol., 119; 239-254. Conclusion Eskenazy, G. 1996. Factors controlling the accumulation of trace elements in coal. - roo. CY, r eo11. -zeozp. The content of the nearly all investigated ele ffjaK., 89, 1; 219-236 Eskenazy, G., E. I. Mincheva, D. P. Rouseva. 1986. Trace ments is highest in the coal from the Samokov, elements in lignite lythotypes from the Elhovo coal ba Pernik and Sofia Basins. Particular some chal sin.- J(oKII. EAH, 39, 10; 99-101. cophile elements have very high concentrations Filippidis, A., Georgakopoulos, A., Kassoli-Fournaraki, A., in the Kyustendil, Karlovo, Oranovo, Maritza Misaelides, P., Yiakkoupis, P., Broussoulis, J. 1996. West and Stanyantzi coal. The lowest concen Trace element contents in composited samples of three lignite seams from the central part of the Drama lignite trations of chalcophile elements are in the Beli deposit, Macedonia, Greece. - Int. J. Coal Geol., 29; breg, Suhostrel and Balkan coal. 219-234. Except for Sn, the investigated elements have Gluskoter, H., Ruch, R., Miller, W., Cahill, R., Dreher, high organic affinity in most of the coal. It re G., Kuhn, J. 1977. Trace elements in coal: occurrence lates specially to the Maritza-West lignite. The and distribution. - III State Geol. Surv., Circ. 499; 155pp. organic affinity is exclusively high there, includ Goodarzi, F. 1987. Elemental concentrations in Canadi ing Sn too. The coal from Belibreg, Gabrovitza an coals, II. Byron Creek Collieries, British Columbia. and particularly Suhostrels make an exception. - Fuel, 66; 250-254. The As and Mo have highest organic affinity Goodarzi, F., Cameron, A. R. 1987. Distribution of ma jor, minor and trace elements in coals of the Kootenay and the Sn has highest inorganic affinity. Cu, Group, Mount Allan, Alberta. - Can. Mineral. , 25; Pb and partially Ag show higher organic affini 555-565. ty. The Zn shows a high organic affinity in some Goodarzi, F., Vander Flier-Keller, E. 1988. Distribution of the basins and high inorganic affinity in the of major, minor and trace elements in Hat Creek De rest of the basins. The optimal interval of pH in posit No 2, British Columbia, Canada. - Chern. Geol., the ancient peat bogs for concentrating of these 70; 313-333. Goodarzi, F., Swaine, D. J. 1993. Chalcophile elements in chalcophile elements with the functional or western Canadian coals. - Int. 1. Coal Geol. , 24; ganic acid groups and for the stability of the el 281 -292. ement-organic compositions is probably 4 and Grieve, D. A., Goodarzi, F. 1993. Trace elements in coal 5.5. Their typical mineral form is sulphide, in samples from active mines in the Foreland Belt, British spite of the fact that Cu, Pb and Zn are estab Columbia, Canada. -Int. 1. Coal Geol., 24; 259-280. Harvey R. D., Cahill, R. A., Chou, C. L., and Steele, J. D. lished as admixtures in the carbonate minerals 1983. Mineral matter and trace elements in the Herrin too. In almost all of the studied coal the chal Springfield coals, Illinois Basin coal field. - Ill. State cophile elements take part in similar geochem Geol. Surv. Contract/Grant Rept., 1983-1984. ical associations in which Ni, Co and Fe often Idzikowski, A., Trzebiatowski, W. 1960. Occurrence of take part too. The correlation coefficients are certain trace elements in the ashes of Upper Silesian coals. -Bull. deL 'acad. Pol. des Sci., geol., geogr., 8, 4; highest between the Pb and Cu or between the 225-243. Pb and Zn. Kortenski, J. 1992. Carbonate minerals in Bulgarian The presence, the distribution and the pre coals with different degrees of coalification. - Int. 1. dominant affinity of the chalcophile elements Coal Geo/., 20; 225-242. are determined mainly by the type of the rocks Kortenski, J., Kostova I. 1996. Occurrence and morphol ogy of pyrite in Bulgarian coals. -Int. 1. Coal Geol., 29; from the coast line, the type of feeding (with 273-290. ground or surface waters), the acidity of the Koyama K., Shirakawa, M ., Takada, J., Katayama, Y., environment in the ancient peat bogs, the de Mastubara, T. 1986. Trace elements in land plants: con gree of fracturing of the coal seams and the centration ranges and accumulators of rare earths. Ba, composition of the mineralised solutions from Ra, Mn, Fe, Co, and heavy halogens.- Research Reactor Institute, Kyoto University, 1-11. which the epigenetic minerals are accumulated. Kuhn J. K., Fiene, F. L., Cahill, R. A., Gluskoter, H. J., Shimp, N. F. 1980. 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