Application of Magnesium Oxide for Metal Removal in Mine Water Treatment

Abstract

In this study low-grade magnesium oxide (MgO) produced by calcinations of natural magnesite was used in mine water treatment using a laboratory-column device. The treatment of mine water from the abandoned Osor mine (NE Spain) with MgO showed the removal of metals from both mine water and tailing leachates. The PHREEQC numerical code and the Geochemist’s Workbench code (GWB) were used to evaluate the speciation of dissolved constituents and calculate the saturation state of the effluents. The analysis of the treated mine water showed the removal of As (from 1.59 to 0.31 μg/L), Cd (from 1.98 to <0.05 μg/L), Co (from 19.1 to <0.03 μg/L), F (from 2730 to 200 μg/L), Mn (from 841 to 0.6 μg/L), Ni (from 17.9 to <2 μg/L, U (from 9.16 to 0.08 μg/L), and Zn (from 2900 to 68.5 μg/L). Pb was also removed (from 98 to 35.2 μg/L) in the treatment of contaminated leachates from the mine waste. The mixing of MgO and water at room temperature may promote the formation of a stabilizing agent composed of hydroxides, carbonates, and magnesium-silicate-hydrates (MSH), which may remove Cd, Zn, and similar metals by sorption on MSH, substitution on the MSH lattice, and precipitation or co-precipitation with some of the hydrated phases.

Synthesis of Green Brucite [NixMg1−x(OH)2] by Incorporation of Nickel Ions in the Periclase Phase (MgO) Applied as Pigments

“…Particularly, water treatment studies have demonstrated MgO's efficiency in the removal of Ni 2+ and Cu 2+ , as well as other metal ions, through precipitation in the stable compound of the brucite crystal phase (Mg(OH) 2 ) [10,11]. Hence, discovering new applications for the precipitate originating from water treatment with MgO may be of interest from the ecological standpoint, as it involves repurposing a byproduct of an already beneficial process.…”