An X-ray spectromicroscopy study of the calcium mineralization in the JEB tailings management facility at McClean Lake, Saskatchewan

Solid mine/mill waste, known as tailings, often contain trace chemical species of interest that cannot be easily identified using bulk analysis methods. Existing methodologies for the identification of trace chemical species within heterogeneous materials, such as the identification of trace Ca-containing carbonates within the gypsum saturated McClean Lake uranium mill tailings, are limited. One methodology previously used in the study of the aforementioned tailings is the combination of X-ray fluorescence (XRF) mapping and Ca K-edge micro X-ray absorption near edge spectroscopy (μ-XANES). This work expands this methodology: Firstly, through use of a fitting procedure that allows a library of 34 XANES spectra collected from Ca-containing standards to be applied to each μ-XANES spectrum collected from the tailings. Secondly, by deeper interrogation of analyte concentrations measured in tailing porewater to rationalize the presence of trace Ca-containing carbonates of interest. It has also been demonstrated in this study that the comparison of the elemental distribution in the tailings determined by XRF mapping to the fitting results of the μ-XANES spectra can be used to help validate the results of the fittings of the μ-XANES spectra. [Display omitted] •Geochemical model suggests precipitation of CaCO3 controls [HCO3−] in pore water.•X-ray microprobe and μ-XANES used to identify many Ca species, including carbonates.•Advancement of spectromicroscopy method enabled identification of trace species.•Extensive study of Ca species indicates that the geochemical model is plausible.