Leaching behavior of trace elements in coal spoils from Yangquan coal mine, Northern China

Abstract

The long-term dumping of coal waste piles has caused serious environmental problems. Release of trace elements (including rare earth elements, REEs) from coal spoils gobs was investigated at Yangquan coal mine, Shanxi Province, China. X-ray diffraction (XRD) was used to analyze the mineral composition of the coal spoils. The minerals of the coal-spoil samples are mainly kaolinite and quartz, with a minor proportion of pyrite. The batch and column tests were employed to simulate the leaching behavior of trace elements from coal spoils. Elements V, Cr, Zn, As, Pb, and Cd are highly enriched in all coal spoils. The coal spoils also have elevated levels of Ga, Ge, Se, Sn, Hf, and Th. The leachate of coal spoils, fried coal spoils and CSFGM (coal spoils fire gas mineral) samples are acidic, with the pH values ranging between 3.0 and 6.6. The released elements with high concentrations (over 100 μg/L) include Fe, Mn, Co, Ni and Zn, while moderately-released elements are Cu, Se, Mo and As. A high content of heavy metals in batch-test leachate with CSFGM indicates an increased mobility of heavy metals in coal spoil combustion byproduct. Within the first hour washing with the electrolyte solution, a rapid rise of common cations, trace elements, and REEs content, as well as a drop of pH value, in effluent was observed. An increased leaching velocity favors the release of trace elements from coal spoils. In addition, the pulse input of precipitation led to more elements to be released than continuous leaching.

Keywords

trace elements / coal spoil / contamination / leaching / column test

References

[1] Ando M., Tadano M., Yamamoto S., . Health Effects of Fluoride Pollution Caused by Coal Burning. Science of the Total Environment, 2001, 271(1–3): 107-116.

[2] Ao W., Huang W., Chen J., . The Concentration of Fluorine in Coals and Spoil of China. Journal of Coal Science and Engineering, 2008, 14(1): 92-96.

[3] Cernuschi S., Giugliano M. Trace Elements Emission Factors from Coal Combustion. Science of the Total Environment, 1987, 65: 95-107.

[4] Chung F. H. Quantitative Interpretation of X-Ray Diffraction Patterns of Mixtures: I. Matrix Flushing Method for Quantitative Multicomponent Analysis. Journal of Applied Crystallography, 1974, 7: 519-525.

[5] Cosca M. A., Essene E. J., Geissman J. W., . Pyrometamorphic Rocks Associated with Naturally Burned Coal Seams, Powder River Basin, Wyoming. American Mineral, 1989, 74: 85-100.

[6] Denimal S., Barbecot F., Dever L., . Chemical and Isotopic Tracing of Underground Water in Relation with Leaching of Mine Spoils, Nord-Pas-de-Calais Coal Basin (France). Bulletin De La Societe Geologique De France, 2001, 172(1): 111-120.

[7] Donovan J. J., Ziemkiewicz P. F. Selenium Adsorption onto Iron Oxide Layers beneath Coal-Mine Overburden Spoil. Journal of Environmental Quality, 2013, 42(5): 1402-1411.

[8] Finkelman R. B. Potential Health Impacts of Burning Coal Beds and Waste Banks. International Journal of Coal Geology, 2004, 51: 19-24.

[9] Gao X. B., Wang Y. X., Hu Q. H., . Effects of Anion Competitive Adsorption on Arsenic Enrichment in Groundwater. Journal of Environmental Science and Health Part A, 2011, 46: 1-9.

[10] Gao X. B., Su C. L., Hu Q. H., . Mobility of Arsenic in Aquifer Sediments at Datong Basin, Northern China: Effect of Bicarbonate and Phosphate. Journal of Geochemical Exploration, 2013, 135: 93-103.

[11] Germani M. S., Zoller W. H. Vapor-Phase Concentrations of Arsenic, Selenium, Bromine, Iodine, and Mercury in the Stack of a Coal-Fired Power Plant. Environmental Science and Technology, 1988, 22: 1079-1085.

[12] Gluskoter H. J., Ruch R. R., Miller W. G., . Trace Elements in Coal: Occurrence and Distribution, 1977, 154.

[13] Godbeer W. G., Swaine D. J., Goodarzi F. Fluorine in Canadian Coals. Fuel, 1994, 73(8): 1291-1293.

[14] Huang W. Z. Study on Spontaneous Combustion Mechanism and Prevention Technology of Coal Spoil, 2004, Chongqing: Chongqing University, 136.

[15] Li T. Elemental Abundance in Oceanic and Continental Crust. Geotectonicaet Metallogenia, 1984, 1: 7-9.

[16] Luo K. L., Ren D. Y., Xu L. R., . Fluorine Content and Distribution Pattern in Chinese Coals. International Journal of Coal Geology, 2004, 57: 143-149.

[17] Park J. H., Li X. F., Edraki M., . Geochemical Assessments and Classification of Coal Mine Spoils for Better Understanding of Potential Salinity Issues at Closure. Environmental Science-Processes and Impacts, 2013, 15(6): 1235-1244.

[18] Pone J. D. N., Hein K. A. A., Stracher G. B., . The Spontaneous Combustion of Coal and Its By-Products in the Witbank and Sasolburg Coalfields of South Africa. International Journal of Coal Geology, 2007, 72: 124-140.

[19] Querol X., Izquierdo M., Monfort E., . Environmental Characterizations of Burnt Coal Spoil Banks at Yangquan, Shanxi Province, China. International Journal of Coal Geology, 2008, 75(2): 93-104.

[20] Shigeo I., Takahisa Y., Kazuo A. Emissions of Mercury and Other Trace Elements from Coal-Fired Power Plants in Japan. Science of the Total Environment, 2006, 368: 397-402.

[21] Stracher G. B., Taylor T. P. Coal Fires Burning Out of Control around the World: Thermodynamic Recipe for Environmental Catastrophe. International Journal of Coal Geology, 2004, 59: 7-17.

[22] Swaine, D. J., 1990). Trace Elements in Coal. Butterworth, London. 278

[23] Taylor R. K. Colliery Spoils Heap Materials-Time Dependent Changes. Ground Engineering, 1974, 7 24.

[24] The Ministry of Land and Resources P.R.C., 2008). Annual Report of Coal Industry in China, 2007–2008 (in Chinese)

[25] Villalba G., Ayres R. U., Schroder H. Accounting for Fluorine-Production, Use, and Loss. Journal of Industrial Ecology, 2007, 11(1): 85-101.

[26] Wiggering H. Sulfide Oxidation—An Environmental Problem within Colliery Spoil Dumps. Environmental Geology, 1993, 22: 99-105.

[27] Wu D. S., Zheng B. S., Wang A. M., . Fluoride Exposure from Burning Coal-Clay in Guizhou Province, China. Fluoride, 2004, 37(1): 20-27.

[28] Zhao Y., Zhang J., Chou C. L., . Trace Element Emissions from Spontaneous Combustion of Gob Piles in Coal Mines, Shanxi, China. International Journal of Coal Geology, 2008, 73: 52-62.

[29] Ziemkiewicz P. F., O’Neal M., Lovett R. J. Selenium Leaching Kinetics and in Situ Control. Mine Water and the Environment, 2011, 30(2): 141-150.