Abstract
The dissolution rates of forsterite and pyrrhotite in a mine tailings deposit as a function of pH were obtained using kinetic testing (leaching test) and PHREEQC inverse modeling. Leach columns containing nickel sulfide mine tailings from four locations in a tailings deposit were subjected to weekly flushing with distilled water. The dissolved moles of forsterite and pyrrhotite were obtained based on the assumption that bulk of the Mg2+ and SO42− present in the leachate come from the dissolution of forsterite and pyrrhotite, respectively. The moles dissolved during a steady-state dissolution period were normalized by the BET and geometric surface areas. The dissolution rate with respect to pH was obtained by regressing the plot of log(rate) and log(H+).This relatively simple method of obtaining dissolution rate of minerals from a heterogeneous material such as mine tailings can be applied to other settings as long as proper mineralogical characterization and modeling constraints are taken into account. The obtained dissolution rates can then be used in reactive transport modeling for the prediction of long-term leachate chemistry of the tailings.
Published Version
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