%0 Journal Article %A Gomez, M. A. %A Hendry, M. J. %A Koshinsky, J. %A Essilfie-Dughan, J. %A Paikaray, S. %A Chen, J. %D 2013 %T Mineralogical Controls on Aluminum and Magnesium in Uranium Mill Tailings: Key Lake, Saskatchewan, Canada %U https://acs.figshare.com/articles/journal_contribution/Mineralogical_Controls_on_Aluminum_and_Magnesium_in_Uranium_Mill_Tailings_Key_Lake_Saskatchewan_Canada/2395990 %R 10.1021/es400658f.s001 %2 https://acs.figshare.com/ndownloader/files/4035679 %K hydrotalcite %K EMPA %K Key Lake %K TEM %K ED %K CanadaThe mineralogy %K raffinate neutralization process %K Mineralogical Controls %K oxic tailings body %K XRD %K Mg mineral phases %K Key Lake U mill %K phases show %K Uranium Mill Tailings %K EDX %K Elemental analyses %K Al %K mineral samples %K U mill tailings %X The mineralogy and evolution of Al and Mg in U mill tailings are poorly understood. Elemental analyses (ICP-MS) of both solid and aqueous phases show that precipitation of large masses of secondary Al and Mg mineral phases occurs throughout the raffinate neutralization process (pH 1–11) at the Key Lake U mill, Saskatchewan, Canada. Data from a suite of analytical methods (ICP-MS, EMPA, laboratory- and synchrotron-based XRD, ATR-IR, Raman, TEM, EDX, ED) and equilibrium thermodynamic modeling showed that nanoparticle-sized, spongy, porous, Mg–Al hydrotalcite is the dominant mineralogical control on Al and Mg in the neutralized raffinate (pH ≥ 6.7). The presence of this secondary Mg–Al hydrotalcite in mineral samples of both fresh and 15-year-old tailings indicates that the Mg–Al hydrotalcite is geochemically stable, even after >16 years in the oxic tailings body. Data shows an association between the Mg–Al hydrotalcite and both As and Ni and point to this Mg–Al hydrotalcite exerting a mineralogical control on the solubility of these contaminants. %I ACS Publications