A techno-economic analysis of diesel exhaust injection into mine tailings for carbon sequestration.

The environmental impact of off-grid mines in remote, cold climates is significantly intensified by their dependence on fossil fuels for power and heating. A promising solution lies in the potential to capture and permanently store carbon within mine tailings, thus allowing the mining industry to take a leading role in carbon removal initiatives and provide sustainable solutions. This study explores energy-optimal design scenarios for flue gas injection into mine waste to capture carbon.

Carbon Sequestration in Biogenic Magnesite and Other Magnesium Carbonate Minerals.

The stability and longevity of carbonate minerals make them an ideal sink for surplus atmospheric carbon dioxide. Biogenic magnesium carbonate mineral precipitation from the magnesium-rich tailings generated by many mining operations could offset net mining greenhouse gas emissions, while simultaneously giving value to mine waste products. In this investigation, cyanobacteria in a wetland bioreactor enabled the precipitation of magnesite (MgCO), hydromagnesite [Mg(CO)(OH)·4HO], and dypingite [Mg(CO)(OH)·5HO] from a synthetic wastewater comparable in chemistry to what is produced by acid leaching of ultramafic mine tailings.

Accelerating Mineral Carbonation Using Carbonic Anhydrase.

Carbonic anhydrase (CA) enzymes have gained considerable attention for their potential use in carbon dioxide (CO2) capture technologies because they are able to catalyze rapidly the interconversion of aqueous CO2 and bicarbonate. However, there are challenges for widespread implementation including the need to develop mineralization process routes for permanent carbon storage. Mineral carbonation of highly reactive feedstocks may be limited by the supply rate of CO2.

Metagenomic analysis reveals that modern microbialites and polar microbial mats have similar taxonomic and functional potential.

Within the subarctic climate of Clinton Creek, Yukon, Canada, lies an abandoned and flooded open-pit asbestos mine that harbors rapidly growing microbialites. To understand their formation we completed a metagenomic community profile of the microbialites and their surrounding sediments. Assembled metagenomic data revealed that bacteria within the phylum Proteobacteria numerically dominated this system, although the relative abundances of taxa within the phylum varied among environments.

A greenhouse-scale photosynthetic microbial bioreactor for carbon sequestration in magnesium carbonate minerals.

A cyanobacteria dominated consortium collected from an alkaline wetland located near Atlin, British Columbia, Canada accelerated the precipitation of platy hydromagnesite [Mg5(CO3)4(OH)2·4H2O] in a linear flow-through experimental model wetland. The concentration of magnesium decreased rapidly within 2 m of the inflow point of the 10-m-long (∼1.5 m(2)) bioreactor.

Accelerated carbonation of brucite in mine tailings for carbon sequestration.

Atmospheric CO(2) is sequestered within ultramafic mine tailings via carbonation of Mg-bearing minerals. The rate of carbon sequestration at some mine sites appears to be limited by the rate of CO(2) supply. If carbonation of bulk tailings were accelerated, large mines may have the capacity to sequester millions of tonnes of CO(2) annually, offsetting mine emissions.

Microbially mediated mineral carbonation: roles of phototrophy and heterotrophy.

Ultramafic mine tailings from the Diavik Diamond Mine, Canada and the Mount Keith Nickel Mine, Western Australia are valuable feedstocks for sequestering CO₂ via mineral carbonation. In microcosm experiments, tailings were leached using various dilute acids to produce subsaline solutions at circumneutral pH that were inoculated with a phototrophic consortium that is able to induce carbonate precipitation. Geochemical modeling of the experimental solutions indicates that up to 2.

Subarctic weathering of mineral wastes provides a sink for atmospheric CO(2).

The mineral waste from some mines has the capacity to trap and store CO(2) within secondary carbonate minerals via the process of silicate weathering. Nesquehonite [MgCO(3)·3H(2)O] forms by weathering of Mg-silicate minerals in kimberlitic mine tailings at the Diavik Diamond Mine, Northwest Territories, Canada. Less abundant Na- and Ca-carbonate minerals precipitate from sewage treatment effluent deposited in the tailings storage facility.

Use of laser spectroscopy to measure the 13C/12C and 18O/16O compositions of carbonate minerals.

The stable carbon and oxygen isotope compositions of carbonate minerals are utilized throughout the earth and environmental sciences for various purposes. Here, we demonstrate the first application of a prototype instrument, based on off-axis integrated cavity output laser spectroscopy, to measure the carbon and oxygen isotope composition of CO(2) gas evolved from the acidification of carbonate minerals. The carbon and oxygen isotope ratios were recorded from absorption spectra of (12)C(16)O(16)O, (13)C(16)O(16)O, and (12)C(16)O(18)O in the near-infrared wavelength region.

Isotopic disequilibrium during uptake of atmospheric CO2 into mine process waters: implications for CO2 sequestration.

Dypingite, a hydrated Mg-carbonate mineral, was precipitated from high-pH, high salinity solutions to investigate controls on carbon fixation and to identify the isotopic characteristics of mineral sequestration in mine tailings. δ(13)C values of dissolved inorganic carbon content and synthetic dypingite are significantly more negative than those predicted for equilibrium exchange of CO(2) gas between the atmosphere and solution. The measured δ(13)C of aqueous carbonate species is consistent with a kinetic fractionation that results from a slow diffusion of atmospheric CO(2) into solution.

Bioleaching of ultramafic tailings by acidithiobacillus spp. for CO2 sequestration.

Bioleaching experiments using various acid-generating substances, i.e., metal sulfides and elemental sulfur, were conducted to demonstrate the accelerated dissolution of chrysotile tailings collected from an asbestos mine near Clinton Creek, Yukon, Canada.

Biologically induced mineralization of dypingite by cyanobacteria from an alkaline wetland near Atlin, British Columbia, Canada.

Background: This study provides experimental evidence for biologically induced precipitation of magnesium carbonates, specifically dypingite (Mg5(CO3)4(OH)2.5H2O), by cyanobacteria from an alkaline wetland near Atlin, British Columbia. This wetland is part of a larger hydromagnesite (Mg5(CO3)4(OH)2.