Mitigating Greenhouse Gas Emissions with Minerals
Abstract
Carbon sequestration or disposal has been recognized as a necessary first step toward the stabilization of atmospheric carbon dioxide (CO2) levels. Of the proposed methodologies for carbon disposal, binding CO2 in carbonate minerals represents the most environmentally benign and geologically stable means of reducing atmospheric carbon levels. By some estimates, as much as 87% of the Earth's carbon is bound in carbonate minerals. Carbon sequestration seeks to accelerate the natural weathering processes responsible for carbon fixation in minerals. Atmospheric CO2 is being fixed in carbonate efflorescences forming in tailings from both inactive and active chrysotile mines. Our data suggest that microbial activity in tailings may mediate the precipitation of more thermodynamically stable hydrated magnesium carbonate phases. Carbonation of kaolinite-serpentine group minerals in ultramafic mine tailings represents a potential implementation of the carbon sequestration process. We have developed a protocol for verifying and quantifying carbon sequestration in mine tailings. Quantitative phase analysis with the Rietveld method and X-ray powder-diffraction data is used to determine the modal abundance of hydrated magnesium carbonates in mine tailings. Stable and radiogenic isotopes are used to fingerprint an atmospheric source for CO2 and to detect contamination by bedrock carbonate. Global implementation of carbon sequestration in ultramafic mine tailings has the potential to draw CO2 directly from the atmosphere at a rate of 10(8) tonnes of carbon per year. In situ sequestration in mine tailings bypasses the need to transport large quantities of tailings to industrial point sources and can be accomplished without high-pressure, high-temperature reactors. Mine tailings may, therefore, represent the optimal environment in which to pursue carbon sequestration in minerals.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2006
- Bibcode:
- 2006AGUSM.V23A..03W
- Keywords:
-
- 3665 Mineral occurrences and deposits;
- 3954 X-ray;
- neutron;
- and electron spectroscopy and diffraction;
- 3994 Instruments and techniques;
- 1041 Stable isotope geochemistry (0454;
- 4870);
- 1631 Land/atmosphere interactions (1218;
- 1843;
- 3322)