Abstract
Acid mine drainage (AMD) is a widespread environmental problem associated with working and abandoned mining operations. It results from the microbial oxidation of pyrite in the presence of water and air, affording an acidic solution that contains toxic metal ions. Pyrite microencapsulation, utilizing silica coating, is a novel approach for controlling AMD that has been shown to be very effective in controlling pyrite oxidation. The roles of the solution pH and silica concentration in the formation mechanism for the AMD-preventing coating were investigated. A silica coating can be formed from silica solution at pH 7, at which the amount of Fe eluted from pyrite into the solution is small. No coating was formed at other pH values, and the amounts of eluted Fe were larger than at pH 7, especially at pH 11. The silica coating forms from 2,500 to 5,000 mg/L silica solutions, but not from 0 or 1,000 mg/L silica solutions. The coating formation rate was slower in the 2,500 mg/L silica solution than in the 5,000 mg/L silica solution. The formation of silica coating on pyrite surfaces depends on three main steps: formation of Fe(OH)3 on the surface of pyrite, reaction between Fe(OH)3 and silicate in the solution on the pyrite surface, and growth of the silica layer on the first layer of silica. The best pH condition to enable these steps was around 7, and the silica coating formation rate can be controlled by the concentration of silica.
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References
Alexander GB (1957) The effect of particle size on the solubility of amorphous silica in water. J Phys Chem 61:1563–1564
Alexander GB, Heston WM, Iler RK (1954) The solubility of amorphous silica in water. J Phys Chem 58:453–455
Evangelou VP (1995) Potential microencapsulation of pyrite by artificial inducement of ferric phosphate coatings. J. Environ. Quality 24:535–542
Evangelou VP (2001) Pyrite microencapsulation technologies: principles and potential field application. Ecol Eng 17:165–178
Faure G (1991) Principles and applications of inorganic geochemistry. Macmillan, New York
Gazea B, Adam K, Kontopoulos A (1996) A review of passive systems for the treatment of acid mine drainage. Miner Eng 9:23–42
Gissinger PB, Alnot M, Ehrhardt JJ, Behra P (1998) Surface oxidation of pyrite as a function of pH. Environ SciTechnol 32:2839–2845
Iler RK (1979) Chemistry of silica. Wiley-Interscience, New York
Marshall WL (1980) Amorphous silica solubilities—I. Behavior in aqueous sodium nitrate solution; 25–300 °C, 0–6 molal. Geochim Cosmochim Acta 44:907–913
Matlock MM, Howerton BS, Atwood DA (2003) Covalent coating of coal refuse to inhibit leaching. Adv Environ Res 7:495–501
Mine Safety Department (MSD), Ministry of International Trade, Industry, Japan (1956) Koen oyobi kouhaisui. Japan Mining Industry Association, Tokyo
Nishiyama T, Hodo T, Yamada M, Bessho M (2003) Preventing the escape of harmful elements using silica coating. J Jpn Soc Eng Geol 43:390–395
Sasowsky ID, Foos A, Miller CM (2000) Lithic controls on the removal of iron and remediation of acidic mine drainage. Water Res 34:2742–2746
Singer PC, Stumm W (1970) Acidic mine drainage: the rate-determining step. Sci 167:1121–1123
Vandiviere MM, Evangelou VP (1998) Comparative testing between conventional and microencapsulation approaches in controlling pyrite oxidation. J Geochem Explor 64:161–176
Zhang YL, Evangelou VP (1998) Formation of ferric hydroxide–silica coatings on pyrite and its oxidation behavior. Soil Sci 163:53–62
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Bessho, M., Wajima, T., Ida, T. et al. Experimental study on prevention of acid mine drainage by silica coating of pyrite waste rocks with amorphous silica solution. Environ Earth Sci 64, 311–318 (2011). https://doi.org/10.1007/s12665-010-0848-0
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DOI: https://doi.org/10.1007/s12665-010-0848-0