Experimental Deployment of Microbial Mineral Carbonation at an Asbestos Mine: Potential Applications to Carbon Storage and Tailings Stabilization

Abstract

A microbial mineral carbonation trial was conducted at the Woodsreef Asbestos Mine (NSW, Australia) to test cyanobacteria-accelerated Mg-carbonate mineral precipitation in mine tailings. The experiment aimed to produce a carbonate crust on the tailings pile surface using atmospheric carbon dioxide and magnesium from serpentine minerals (asbestiform chrysotile; Mg 3 Si 2 O 5 (OH) 4 ) and brucite [Mg(OH) 2 ]. The crust would serve two purposes: Sequestering carbon and stabilizing the hazardous tailings. Two plots (0.5 m 3 ) on the tailings pile were treated with sulfuric acid prior to one plot being inoculated with a cyanobacteria-dominated consortium enriched from the mine pit lakes. After 11 weeks, mineral abundances in control and treated tailings were quantified by Rietveld refinement of powder X-ray diffraction data. Both treated plots possessed pyroaurite [Mg 6 Fe 2 (CO 3 )(OH) 16 ·4H 2 O] at 2 cm depth, made visible by its orange-red color. The inoculated plot exhibited an increase in the hydromagnesite [Mg 5 (CO 3 ) 4 (OH) 2 ·4H 2 O] content from 2-4 cm depth. The degree of mineral carbonation was limited compared to previous experiments, revealing the difficulty of transitioning from laboratory conditions to mine-site mineral carbonation. Water and carbon availability were limiting factors for mineral carbonation. Overcoming these limitations and enhancing microbial activity could make microbial carbonation a viable strategy for carbon sequestration in mine tailings.

Solubility of the hydrated Mg-carbonates nesquehonite and dypingite from 5 to 35 °C: Implications for CO2 storage and the relative stability of Mg-carbonates

“…Several engineered carbon mineralization approaches have been studied at the laboratory and/or pilot-scale, including injection of CO 2 into subsurface basaltic or ultramafic rock (Kelemen and Matter, 2008;Power et al, 2013a, b;Gislason and Oelkers, 2014;Matter et al, 2016), passive or accelerated carbonation of ultramafic mine waste rock and tailings (Wilson et al, 2006(Wilson et al, , 2011(Wilson et al, , 2014Power et al, 2010Power et al, , 2014aPronost et al, 2011Pronost et al, , 2012Bea et al, 2012;Beinlich and Austrheim, 2012;Harrison et al, 2013aHarrison et al, , b, 2015Harrison et al, , 2016Oskierski et al, 2013;Assima et al, 2012Assima et al, , 2014aMcCutcheon et al, 2015McCutcheon et al, , 2017Gras et al, 2017), and accelerated mineralization in high pressure/high temperature ex situ reactors (Lackner et al, 1995;Gerdemann et al, 2007). Enhanced weathering is a related approach that aims primarily to sequester CO 2 in dissolved form, but can also induce carbonate precipitation.…”

“…The multitude of potential metastable hydrated 69 phases complicates prediction of Mg-carbonate formation and thus the stability of the CO 2storing phase (Königsberger et al, 1999;Hopkinson et al, 2008Hopkinson et al, , 2012Hänchen et al, 2008;Montes-Hernandez et al, 2012;Kristova et al, 2014). To reduce some of the ambiguity in the prediction of Mg-carbonate mineral formation under various conditions, in this study we determine the solubility of nesquehonite [MgCO 3 •3H 2 O] and dypingite [Mg 5 (CO 3 ) 4 (OH) 2 •(5 or)8H 2 O], two commonly observed products of carbon mineralization in ultramafic materials (Wilson et al, 2006(Wilson et al, , 2011(Wilson et al, , 2014Boschi et al, 2009;Zhao et al, 2010;Pronost et al, 2011;Schaef et al, 2011;Bea et al, 2012;Loring et al, 2012;Montes-Hernandez et al, 2012;Assima et al, 2012Assima et al, , 2014cHövelmann et al, 2012;Felmy et al, 2012;Beinlich and Austrheim, 2012;Schaef et al, 2013;Harrison et al, 2013aHarrison et al, , 2015Harrison et al, , 2016Harrison et al, , 2017Power et al, 2013aPower et al, , b, c, 2014bKristova et al, 2014;McCutcheon et al, 2016;Chaka et al, 2016;Garcia del Real et al, 2016;Highfield et al, 2016;Gras et al, 2017;McCutcheon et al, 2017), and the transformation process that converts nesquehonite to dypingite. Both nesquehonite and dypingite are readily formed during reaction of Mg-rich minerals with CO 2 at ambient te...…”

Fate of transition metals during passive carbonation of ultramafic mine tailings via air capture with potential for metal resource recovery

“…The transition metals of interest in this study (Fe, Cr, Ni, Mn, Co) substitute for Mg 2+ in the more reactive 'brucite layer' within the structures of serpentine minerals (Anbalagan et al, 2008;Anbalagan et al, 2010;Ristić et al, 2011) meaning they are likely to be leached along with Mg during passive weathering or engineering solutions for accelerated leaching of tailings. Si forms strong bonds with oxygen within the serpentine structure, and is expected to be relatively immobile under the circumneutral conditions that occur during weathering of serpentinite (e.g., McCutcheon et al, 2015McCutcheon et al, , 2017. Our XFM data indicate that Si is restricted to serpentine grains whereas Fe and trace transition metals (Cr, Ni, Mn, Co) are incorporated into hydromagnesite cements at comparable concentrations, although slightly lower than those found in unweathered serpentine (Tables 1, 2; Figs.…”

“…Weathering has formed a Mg-carbonate-rich crust at the surface of the Woodsreef tailings, but the bulk of the tailings at depth appear to be less altered, thus the tailings are considered an attractive target material for promoting mineral carbonation reactions (McCutcheon et al, 2015(McCutcheon et al, , 2016(McCutcheon et al, , 2017Oskierski et al, 2013;Turvey et al, 2017). We find that the bulk of trace transition metals within the tailings remain within the original mineral assemblage, of silicates, oxides and alloys, with some metals having been mobilised and then sequestered within alteration minerals (hydromagnesite and possibly pyroaurite) in surface crusts, and none detected in mine pit waters.…”

Improving the Performance of Entities in the Mining Industry by Optimizing Green Business Processes and Emission Inventories

“…It allows an organization to evaluate its business process performance based on six criteria: culture, methods, technology, people, strategic alignment, and governance [7,31]. In order to achieve the goal of managing green business processes, information technology and systems should be integral parts of the maturity model [32,33].…”