21 1 Research of Environmental Sciences Vol. 21,No. 1,2008 1, 1,2 3, 2, 3, 1, 1 1.,, 330031 2., 100101 3., 550002 :,,, CaCO 3. :,,1 h ;,900 80 %, ; CaCO 3, CaCO 3, w (CaCO 3 ) 10 % ;500 800,800, 4412 %,,900 2510 %. : ; CaCO 3 ; ; : X506 : A : 1001-6929(2008) 01-0133 - 06 Regularity and Co ntrol of Fluorine Relea se fro m Co al2clay Briquette Co mbustio n in Op en Gro und2stove CHEN Cheng2guang 1, WU Dai2she 1,2, WANG Wu2yi 2, ZHENG Bao2shan 3, XIAO Hua2yun 1, LI Ping 1 1. Key Lab of Poyang Lake Ecology and Bio2resource Utilization, Ministry of Education ; College of Environmental Science and Engineering, Nanchang University, Nanchang 330031, China 2. Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China 3. Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China Abstract : A precise temperature regulating open furnace was devised to describe and analyze the regularity and control of fluoride emission from coal2clay briquette combustion in open ground2stove in the serious coal2clay combustion type fluorosis areas, the effect of retention period and combustion temperature on fluorine emission and the relationship of fluorine retention with the dosage of CaCO 3 and combustion temperature were obtained. Experimental results indicate that fluorine emission tends to increase with increasing retention period or combustion temperature, and the fluorine emission rate keeps stabile after 1 h. The average fluorine emission rate reaches 80 % at900, this is similar to the fluorine emission rate under usual combustion condition. Selecting CaCO 3 as calcium2based sorbent can decrease fluoride release from coal2clay briquette combustion effectively, fluorine retention tends to increase with increasing the dosage of CaCO 3, and the optimum condition for fluorine retention is blending 10 % CaCO 3 with coal2clay briquette. Fluorine retention rate tends to increase with increasing combustion temperature from 500 to 800, it reaches the highest rate at 800, and the average fluorine retention rate is 4412 %. But above 800, fluorine retention rate declines versus combustion temperature, at 900, it reaches 2510 %. Key words : coal2clay briquette ; CaCO 3 ; fluorine retention ; fluorine emission : 2007-05 - 08 : 2007-09 - 07 : (40601004,40473047) ; (2004BA704B03) ; ; : ( 1983 - ),,,, chengguangchen @yahoo. com. cn. 3,dswu @ncu. edu. cn ( F) [122 ], 2004, 13 200, 18 011 912 1 517 399 [3 ]. 3, [4 ], [5210 ].,,
134 21,, 50 % w (F) (TJ 36-79) [11212 ].,,., [13230 ],,, [13,16220 ] [14,21225 ].,.,,.,. 1 1. 1, w (F) 73 mgπkg., w (F), 7, 1. 200 (01076 mm),. 1 Table 1 Fluorine concentrations of clays 1. 2 w (F)Π(mg kg - 1 ) 1 1 242 2 1 642 3 2 620 4 3 940 5 5 753 6 7 017 7 16 362. : 20 g, (Millipore Direct - Q ), 1 cm,. : 14 g, 6 g,. CaCO 3 : 14 g, 6 g, 012,014,016,018, 110,112,116,210 310 g, w (CaCO 3 ) 1 %, 2 %, 3 %, 4 %, 5 %, 6 %,8 %,10 % 15 %,. 1. 3, 1 1,, KSYD ( ),. 1,. 900,, 1., 1 cm. 1 ;2 ;3 ; 4 ;5 ;6 1 Fig. 1 Precise temperature regulating open furnace 1. 4 11411 20 g,5 3 8,, 24, 800, 5,10,20,30,40,60, 90,120 min 3 1,, 200 (01076 mm) w (F). 11412 CaCO 3 112,, 800 1 h,, 200 ( 01076 mm) w (F).
1 : 135 11413 CaCO 3 7 7 7 10 % ( ) CaCO 3 ( 112 ) 5,,, 500,600,700, 800 900, 1 h, 1,, 200 (01076 mm) w (F). 1. 5 ( GBΠT4633-1997), - 100 (0115 mm), w (F),,. 1. 6 ( ) w (F),, : = ( ) Π ( ) 100 % = - CaCO 3 2. 2. 1 2. 2 Fig. 2 Effects of retention time on fluorine emission 2,,,, 30,120 60 min. [17 ], 1 100 50 min, 900 7513 %. [13 ], 900 75141 %., 800 30 min,, 95 %.,,., [20,31233 ].,.,. [25 ], 800 1 h,, (2 h),,,. [20 ]., 7518 %, (8015 %),,,. 1 h, 1 h. 2. 2.,, 500 900,,, 950. 950,,, 500 900., w ( ) 30 %. 7 m ( ) m ( ) 7 3 7, 1 h 3. 3,,600,600. [13,17218 ], [25 ],. 2,800,,
136 21 w (F)Π(mg kg - 1 ) :1 423. 7 ; 2 543. 7 ; 3 837. 1 ; 4 1 233. 1 ; 5 1 777. 0 ; 6 2 156. 2 ; 7 4 959. 7 3 Fig. 3 Effects of burning temperature on fluorine emission during coal2clay briquettes combustion. [13,16220 ], [22 ].,,,, 800 [20,31233 ]. 900,. [5,8 ], 8012 %, 900. 2 Table 2 Fluorine emission rates of coals, clays and coal2clay briquettes at different temperatures % Π 500 600 700 800 900 1618 2410 3915 5510 7518 [17 ] 1) 1616 2918 3119 3715 6311 [18 ] 1) 1813 3414 7514 [13] 117 1310 3214 5513 7217 [22] 1). 1018 414 1511 712 3013 1014 5811 1410 8010 1216 2. 3 CaCO 3 CaCO 3 630 780, 600, [24,34 ]. 300 400, 400 600,,,, [24 ]. CaCO 3,. CaCO 3 4., CaCO 3. CaCO 3, w (CaCO 3 ) 1 % 24 %, 10 %, 5411 %, CaCO 3. CaCO 3, [28 ]. 2. 4 CaCO 3 7 10 % CaCO 3, CaCO 3 5. 4 CaCO 3 Fig. 4 Effects of CaCO 3 molar ratio on fluorine emission rate 5, 500 800, CaCO 3. 500 600,, 114 % 812 %, 700 2718 %,800, 4412 %,, 900 2510 %. CaCO 3 630, CaCO 3, 780 CaCO 3 [34 ],, HF : CaO + 2HF CaF 2 + H 2 O (1),
1 : 137 w (F)Π(mg kg - 1 ) : 1 423. 7 ; 2 543. 7 ; 3 837. 1 ; 4 1 233. 1 ; 5 1 777. 0 ; 6 2 156. 2 ; 7 4 959. 7 5 w( CaCO 3 ) 10 % Fig. 5 Effects of burning temperatures on fluorine retention rates of coal2clay briquettes additive with 10 % CaCO 3, 800 (1),. w (F)Π(mg kg - 1 ) :1 423. 7 ; 2 543. 7 ; 3 837. 1 ; 4 1 233. 1 ; 5 1 777. 0 ; 6 2 156. 2 ; 7 4 959. 7 6 w( CaCO 3 ) 10 % Fig. 6 Effects of burning temperatures on fluorine emission rates of coal2clay briquettes additive with 10 % CaCO 3 CaCO 3 6. 500 700,, 700, 214 %,. 800 20 %, 900 55 %,.,, [35 ].. 3 a.,,, 1 h. b.,. 900 80 %,. c. CaCO 3,, 10 %. d. CaCO 3,500 800,800, 4412 %,,900 2510 %. e. CaCO 3, 10 %, 800 20 %, 900 55 %,,. : [ 1 ]. [ M]. :, 1992 :91299. [ 2 ] Zheng B S, Ding Z H, Huang R G, et al. Issues of health and disease relating to coal use in southwestern China [J ]. Int J Coal Geol, 1999, 40 :1192132. [ 3 ],,. [J ].,2001, 14(6) :44246. [ 4 ],,,. [J ].,2005, 24 (4) :4682 471. [ 5 ] Wu D S, Zheng B S, Wang A M, et al. Fluoride exposure from burning coal2clay in Guizhou Province, China[J ]. Fluoride, 2004, 37(1) :20227. [ 6 ] Wu D S, Zheng B S, Tang X Y, et al. Fluorine in Chinese coals [J ]. Fluoride, 2004, 37(2) :1252132. [ 7 ] Dai S F, Ren D Y, Ma S M. The cause of endemic fluorosis in western Guizhou Province, Southwest China [J ]. Fuel, 2004, 83 : 209522098. [ 8 ],,. [J ].,2004, 23(2) :1352137. [ 9 ],,,. [J ].,2005, 26(1) :7211. [10],,,. [J ].,2005, 51(1) :42245.
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