Mineralogical Characterization of Mine Tailings Containing Arsenic From Zimapan, Mexico.

MINERALOGICAL CHARACTERIZATION OF MINE TAILINGS CONTAINING ARSENIC FROM ZIMAPÁN, MEXICO Luke Morgan (Icbneumon@TAMU.edu), Youjun Deng, Texas A&M University, College Station, TX USA Heavy metals can be found in acid mine drainage (AMD) and raise concerns for difficult remediation efforts. In such places, complex geochemical processes occur after weathering of mine tailings. Thereafter, newly formed colloids and nanoparticles can significantly affect the transformation and transport of heavy metals and the metalloid, arsenic. Arsenic containing colloids and nanoparticles are susceptible to environmental changes because of their large surface area, structural defects, and incorporation of several elements into their structure. Oxidation states of such weathered arsenic-containing materials may be eluded using multiple modern techniques, further complementing previous data inquisition. AMD samples were collected from a site in Zimapán, Mexico, a location abundant in limestone. In house, at Texas A&M University, these samples from Mexico have been fractionated and examined with rudimentary mineralogy techniques, multiple treatments, and with modern SEM, TEM, FTIR, and XRD tools. Jarosite, goethite, galena, elemental sulfur, lepidocrocite, pyrite, gypsum, orthoclase, muscovite, and quartz were identified in the mine tailing samples. In addition, the same samples were taken to Argonne National Laboratory and undergone X-ray Absorption and X-ray Fluorescence spectroscopy to elucidate arsenic speciation. Specific elemental speciation can help understand arsenic’s potential mobility and bioavailability in the environment. Synchrotron data confirmed As(V) is present in the samples, while XRF helped distinguish correlations with abundant iron. The association of As(V) with abundant iron (oxy)hydroxide minerals are further observed to understand their potential to sorb, co-precipitate, and react.