The aim of this study was to develop and examine the morphology and
distribution of mercury (Hg) in flue gas desulfurization (FGD) by-product.Mercury
in the coal of coal-fired power plants is concentrated in the by-products of
desulfurization process, and it is widely used as an additive in cement,
building materials and other industries. Due to the different stability of
various forms of mercury in the environment, subsequent use of products
containing desulfurization by-product additives will continue to be released
into the environment, endangering human health. Therefore, it is very necessary
to study the form and distribution of mercury in the by-products of
desulfurization in coal-fired power plants to provide a theoretical basis for
subsequent harmless treatment.For
content and morphology of mercury analysis, 1 sample of dry FGD ash and 6
samples of wet FGD gypsum were analyzed. The total 7 samples were extracted
using a modification of sequential chemical extractions (SCE) method, which was
employed for the partitioning Hg into four fractions: water soluble, acid
soluble, H2O2 soluble, and
residual. The Hg analysis was done with United States Environmental Protection
Agency (USEPA) method7471B. Comparing with the wet FGD gypsums of coal-fired boilers, the
total Hg content in the dry FGD by-product was as high as1.22
mg/kg, while the total Hg content in the FGD gypsum is 0.23-
References
[1]
Zhang, J.Y., Ren, D., Xu, D., et al. (1999) The Distribution of Mercury in Major Associated Minerals from Coal Beds in Southwestern Guizhou. Geological Review, 45, 539-542.
[2]
Carpi, A. (1997) Mercury from Combustion Sources: A Review of the Chemical Species Emitted and Their Transport in the Atmosphere. Water, Air and Soil Pollution, 98, 241-254. https://doi.org/10.1007/BF02047037
[3]
William, L.B., Karl, S. and Kandance, K. (2007) Testing Mechanisms of Mercury Retention in FGD Products. The 2007 World of Coal Ash Conference, Vol. 5, 7-10.
[4]
Izquierdo, M.T., De Las Obras-Loscertales, M., De Diego, L.F., et al. (2017) Mercury Emissions from Coal Combustion in Fluidized Beds under Oxy-Fuel and Air Conditions: Influence of Coal Characteristics and O2 Concentration. Fuel Processing Technology, 167, 695-701. https://doi.org/10.1016/j.fuproc.2017.08.021
[5]
Chu, P. and Porcella, D.B. (1995) Mercury Stack Emissions from U.S. Electric Utility Plants. Water Air Soil Pollution, 80, 135-144. https://doi.org/10.1007/978-94-011-0153-0_16
[6]
Yang, Y.F., Huang, Q.F. and Wang, Q. (2012) Ignoring Emissions of Hg from Coal Ash and Desulfurized Gypsum Will Lead to Ineffective Mercury Control in Coal-Fired Power Plants in China. Environmental Science & Technology, 46, 3058-3059. https://doi.org/10.1021/es300786d
[7]
Cheng, C.M., Chang, Y.N., Sistani, K., et al. (2009) Emission and Leaching Potential of Mercury from Flue Gas Desulfurization (FGD) By-Products Amended Soil. World of Coal Ash Conference, Lexington, Vol. 5, 4-7.
[8]
Senior, C.L., Helble, J.J. and Sarofim, A.F. (2000) Emissions of Mercury, Trace Elements, and Fine Particles from Stationary Combustion Sources. Fuel Processing Technology, 65-66, 263-288. https://doi.org/10.1016/S0378-3820(00)00082-5
[9]
Wang, H., Duan, Y., Li, Y.N., et al. (2016) Experimental Study on Mercury Oxidation in a Fluidized Bed under O2/CO2 and O2/N2 Atmospheres. Energy & Fuels, 30, 5065-5070. https://doi.org/10.1021/acs.energyfuels.6b00457
[10]
Tessier, A., Campbell, P.G.C. and Bisson, M. (1979) Sequential Exaction Procedure for the Speciation of Particulate Trace Metals. Analytical Chemistry, 51, 844-851. https://doi.org/10.1021/ac50043a017
[11]
David, O.C., Hou, D.Y., Yong, S.O., et al. (2017) Mercury Speciation, Transformation, and Transportation in Soils, Atmospheric Flux, and Implications for Risk Management: A Critical Review. Environment International, 126, 747-761. https://doi.org/10.1016/j.envint.2019.03.019
[12]
Neculita, C.M., Zagury, G.J. and Deschênes, L. (2005) Mercury Speciation in Highly Contaminated Soils from Chlor-Alkali Plants Using Chemical Extractions. Journal of Environmental Quality, 34, 255-262.
[13]
Park, C.H.E., Lee, Y., Lee, L.J.-E., et al. (2013) Simple and Accessible Analytical Methods for the Determination of Mercury in Soil and Coal Samples. Chemosphere, 93, 9-13. https://doi.org/10.1016/j.chemosphere.2013.04.044
Ma, X.X., Kaneko, T., Tsutomu, T., et al. (2000) Use of Lime for SO2 Removal from Flue Gas in the Semidry FGD Process with a Powder-Particle Spouted Bed. Chemical Engineering Science, 55, 4643-4652. https://doi.org/10.1016/S0009-2509(00)00090-7
[16]
Sanders, J.F., Keener, T.C. and Wang, J. (1995) Heated Fly Ash/Hydrated Lime Slurries for SO2 Removal in Spray Dryer Absorbers. Industrial & Engineering Chemistry Research, 34, 302-307. https://doi.org/10.1021/ie00040a032
[17]
Joseph, R.V.F., Richard, A.H., William, J.O.D., et al. (2003) Modeling Sorbent Injection for Mercury Control in Baghouse Filters: II—Pilot-Scale Studies and Model Evaluation. Journal of the Air & Waste Management Association, 53, 489-496. https://doi.org/10.1080/10473289.2003.10466172
[18]
Zhao, Y.C., Zhang, J.Y., Liu, J., et al. (2010) Study on Mechanism of Mercury Oxidation by Fly Ash from Coal Combustion. Engineering Thermophysics, 55, 163-167. https://doi.org/10.1007/s11434-009-0567-7
[19]
Bhardwaj, R., Chen, X. and Vidic, R.D. (2012) Impact of Fly Ash Composition on Mercury Speciation in Simulated Flue Gas. Journal of the Air & Waste Management Association, 59, 1331-1338. https://doi.org/10.3155/1047-3289.59.11.1331
