Regularity and Co ntrol of Fluorine Relea se fro m Co al2clay Briquette Co mbustio n in Op en Gro und2stove

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1 21 1 Research of Environmental Sciences Vol. 21,No. 1,2008 1, 1,2 3, 2, 3, 1, 1 1.,, , , :,,, CaCO 3. :,,1 h ;, %, ; CaCO 3, CaCO 3, w (CaCO 3 ) 10 % ; ,800, 4412 %,, %. : ; CaCO 3 ; ; : X506 : A : (2008) 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 , China 2. Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing , China 3. Institute of Geochemistry, Chinese Academy of Sciences, Guiyang , 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 : : : ( , ) ; (2004BA704B03) ; ; : ( ),,,, com. cn. edu. cn ( F) [122 ], 2004, , [3 ]. 3, [4 ], [5210 ].,,

2 134 21,, 50 % w (F) (TJ 36-79) [11212 ].,,., [13230 ],,, [13,16220 ] [14,21225 ].,.,,., , w (F) 73 mgπkg., w (F), 7, (01076 mm),. 1 Table 1 Fluorine concentrations of clays 1. 2 w (F)Π(mg kg - 1 ) : 20 g, (Millipore Direct - Q ), 1 cm,. : 14 g, 6 g,. CaCO 3 : 14 g, 6 g, 012,014,016,018, 110,112,116, 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 g,5 3 8,, 24, 800, 5,10,20,30,40,60, 90,120 min 3 1,, 200 (01076 mm) w (F) CaCO 3 112,, h,, 200 ( mm) w (F).

3 1 : CaCO % ( ) CaCO 3 ( 112 ) 5,,, 500,600,700, , 1 h, 1,, 200 (01076 mm) w (F) ( GBΠT ), (0115 mm), w (F),, ( ) w (F),, : = ( ) Π ( ) 100 % = - CaCO Fig. 2 Effects of retention time on fluorine emission 2,,,, 30, min. [17 ], min, %. [13 ], %., min,, 95 %.,,., [20,31233 ].,.,. [25 ], h,, (2 h),,,. [20 ]., 7518 %, (8015 %),,,. 1 h, 1 h ,, ,,, ,,, , w ( ) 30 %. 7 m ( ) m ( ) 7 3 7, 1 h 3. 3,,600,600. [13,17218 ], [25 ],. 2,800,,

4 w (F)Π(mg kg - 1 ) : ; ; ; ; ; ; Fig. 3 Effects of burning temperature on fluorine emission during coal2clay briquettes combustion. [13,16220 ], [22 ].,,,, 800 [20,31233 ]. 900,. [5,8 ], 8012 %, Table 2 Fluorine emission rates of coals, clays and coal2clay briquettes at different temperatures % Π [17 ] 1) [18 ] 1) [13] [22] 1) CaCO 3 CaCO , 600, [24,34 ] , ,,,, [24 ]. CaCO 3,. CaCO 3 4., CaCO 3. CaCO 3, w (CaCO 3 ) 1 % 24 %, 10 %, 5411 %, CaCO 3. CaCO 3, [28 ] CaCO % CaCO 3, CaCO CaCO 3 Fig. 4 Effects of CaCO 3 molar ratio on fluorine emission rate 5, , CaCO ,, 114 % 812 %, %,800, 4412 %,, %. CaCO 3 630, CaCO 3, 780 CaCO 3 [34 ],, HF : CaO + 2HF CaF 2 + H 2 O (1),

5 1 : 137 w (F)Π(mg kg - 1 ) : ; ; ; ; ; ; 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 ) : ; ; ; ; ; ; w( CaCO 3 ) 10 % Fig. 6 Effects of burning temperatures on fluorine emission rates of coal2clay briquettes additive with 10 % CaCO 3 CaCO ,, 700, 214 %, %, %,.,, [35 ].. 3 a.,,, 1 h. b., %,. c. CaCO 3,, 10 %. d. CaCO 3, ,800, 4412 %,, %. e. CaCO 3, 10 %, %, %,,. : [ 1 ]. [ M]. :, 1992 : [ 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 : [ 3 ],,. [J ].,2001, 14(6) : [ 4 ],,,. [J ].,2005, 24 (4) : [ 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) : [ 6 ] Wu D S, Zheng B S, Tang X Y, et al. Fluorine in Chinese coals [J ]. Fluoride, 2004, 37(2) : [ 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 : [ 8 ],,. [J ].,2004, 23(2) : [ 9 ],,,. [J ].,2005, 26(1) :7211. [10],,,. [J ].,2005, 51(1) :42245.

6 [11]. [J ].,1991, 10 (6) : [12],. [J ].,1999, 10(5) : [13]. [J ].,1989, 11(3) : [14],,,. [J ].,1994, 6(4) : [15],,,. [J ].,1999, 20(5) : [16],,,. CaO [J ].,2003, 54(2) : [17],,,. [J ].,2003, 31(5) : [18],,,. [J ].,2004, 25(5) : [19],,,. ( ) [J ].,2005, 24(4) : [20],,,. ( ) [J ].,2005, 24 (5) : [21] Gerald D. Relationship between fluorine emission during firing of ceramic products and firing temperature and composition of raw material[j ]. Applied Clay Science, 1987, 2 :129. [22]. [J ]., 1997, 16(6) : [23],,. [J ].,2002, 21(2) :75278,82. [24],,,. [J ].,2002, 24 (4) :59262, 68. [25],,,. [J ].,2001, 22(2) : [26],,. [J ].,1995, 29(2) :125. [27]. [J ].,1997, 12(1) : [28]. CaO CaCO 3 [J ].,2001, 20(5) :399. [29],,,. [J ].,1995, 10(5) : [30],. [J ].,2000(3) : [31] Deadmore D L. Stability of inorganic fluorine bearing compounds [J ]. J Am Ceram Soc, 1962, 45(3) : [32] Troll G, Farzaneh A. Fluorine loss in production of bricks and comparison with the loss in fluorine2bearing minerals [ J ]. Interceram, 1978, 4(5) : [33],,,. CaF 2 [J ].,2002, 23(3) : [34],,,. [J ].,2002,30 (4) : [35],,,. [J ].,2004, 24(7) : ( : )