Title: Mineralogical constraints on the mobility of arsenic in tailings from Zimapan, Hidalgo, Mexico

Authors: F.M. Romero, M.A. Armienta, G. Villasenor, J.L. Gonzalez

Addresses: Posgrado en Ciencias de la Tierra, UNAM, Mexico, Mexico DF, 04510, Mexico. ' Instituto de Geofisica, UNAM, Ciudad Universitaria, Mexico DF 04510, Mexico. ' Instituto de Geologia, UNAM, Mexico, Mexico D.F., 04510, Mexico. ' Facultad de Quimica, UNAM, Mexico, Mexico D.F. 04510, Mexico

Abstract: Arsenic mobility was studied in tailings from Zimapan, a mining zone of Mexico. Primary mineral phases are quartz, calcite, pyrite, pyrrhotite, sphalerite and arsenopyrite. Secondary minerals in oxidised tailings include gypsum, K-jarosite, lepidocrocite, goethite, beudantite and kaolinite. The highest levels of As (up to 3.95 ± 2.29 weight %), Zn (up to 3.26 ± 2.21 weight %) and Pb (up to 0.93 ± 0.83 weight %) were measured in unoxidised tailings located at the edge of the town. Concentrations in water leachates from oxidised tailings were: As (0.41–48.68 mg/L), Zn (1.5–400 mg/L), Pb (<1.0–1.8 mg/L) and Fe (1.9–897.5 mg/L). Mineralogy, pH, and heterogeneity of tailings, explain these concentration ranges. Arsenopyrite oxidation releases arsenic that is then partly incorporated in secondary minerals like beudantite and K-jarosite. Arsenic is also immobilised by sorption onto positively charged surfaces of hydrous ferric oxides.

Keywords: arsenic mobility; mining; mineralogy; metals; oxidised tailings; Mexico; water leachates; secondary minerals; arsenopyrite oxidation; arsenic concentrations; sorption; chemistry; environmental pollution.

DOI: 10.1504/IJEP.2006.009097

International Journal of Environment and Pollution, 2006 Vol.26 No.1/2/3, pp.23 - 40

Available online: 02 Mar 2006 *

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