Field-based accounting of CO2 sequestration in ultramafic mine wastes using portable X-ray diffraction
Connor C. Turvey, Siobhan A. Wilson, Jessica L. Hamilton, Gordon Southam
School of Earth Atmosphere and Environment
Carbon mineralization, the sequestration of carbon within minerals, presents one method through which we could control rising levels of anthropogenic carbon dioxide (CO2) emissions. The mineral wastes produced by some ultramafic-hosted mines have the ability to sequester atmospheric CO2 via passive carbonation reactions. Carbon accounting in mine tailings is typically performed using laboratory-based quantitative X-ray diffraction (XRD) or thermogravimetric methods, which are used to measure the abundances of carbonate-bearing minerals such as hydromagnesite [Mg5(CO3)4(OH)2·4H2O] and pyroaurite [Mg6 Fe23+ $\text{Fe}^{3+}-{2}$ (CO3)(OH)16·4H2O]. The recent development of portable XRD instruments now allows for the characterization and quantification of minerals in the field. Here we assess the feasibility of using a portable XRD instrument for field-based carbon accounting in tailings from the Woodsreef Chrysotile Mine, New South Wales, Australia. Modal mineralogy was obtained by Rietveld refinements of data collected with an inXitu Terra portable XRD. The Partial Or No Known Crystal Structures (PONKCS) method was used to account for turbostratic stacking disorder in serpentine minerals, which are the dominant phases in tailings from Woodsreef. Weighed mixtures of synthetic tailings were made to evaluate the precision and accuracy of quantitative phase analysis using the portable instrument. An average absolute deviation (bias) of 8.2 wt% from the actual composition of the synthetic tailings was found using the portable instrument. This is comparable to the bias obtained using a laboratory-based diffractometer (9.6 wt% absolute) and to the results from previous quantitative XRD studies involving serpentine minerals. The methodology developed using the synthetic tailings was then applied to natural tailings samples from Woodsreef. Surface crusts forming on the tailings pile were found to contain hydromagnesite (∼5.8 wt%) and pyroaurite (∼2.1 wt%). Comparable results were obtained using the laboratory-based instrument and these results are expected to have similar biases to the analyses of the synthetic tailings. These findings demonstrate that portable XRD instruments may be used for field-based measurement of carbon sequestration in minerals in engineered and natural environments.
American Mineralogist
https://doi.org/10.2138/am-2017-5953
carbon mineralization
hydromagnesite
PONKCS method
portable X-ray diffraction
pyroaurite
Rietveld refinement
10.2138/am-2017-5953
Turvey, C. C., Wilson, S. A., Hamilton, J. L., & Southam, G. (2017). Field-based accounting of CO2 sequestration in ultramafic mine wastes using portable X-ray diffraction. American Mineralogist, 102(6), 1302-1310. https://doi.org/10.2138/am-2017-5953
Turvey, Connor C. ; Wilson, Siobhan A. ; Hamilton, Jessica L. ; Southam, Gordon. / Field-based accounting of CO2 sequestration in ultramafic mine wastes using portable X-ray diffraction. In: American Mineralogist. 2017 ; Vol. 102, No. 6. pp. 1302-1310.
@article{7a10cfaf6d1540e280ac419bedae55af,
title = "Field-based accounting of CO2 sequestration in ultramafic mine wastes using portable X-ray diffraction",
abstract = "Carbon mineralization, the sequestration of carbon within minerals, presents one method through which we could control rising levels of anthropogenic carbon dioxide (CO2) emissions. The mineral wastes produced by some ultramafic-hosted mines have the ability to sequester atmospheric CO2 via passive carbonation reactions. Carbon accounting in mine tailings is typically performed using laboratory-based quantitative X-ray diffraction (XRD) or thermogravimetric methods, which are used to measure the abundances of carbonate-bearing minerals such as hydromagnesite [Mg5(CO3)4(OH)2·4H2O] and pyroaurite [Mg6 Fe23+ $\text{Fe}^{3+}-{2}$ (CO3)(OH)16·4H2O]. The recent development of portable XRD instruments now allows for the characterization and quantification of minerals in the field. Here we assess the feasibility of using a portable XRD instrument for field-based carbon accounting in tailings from the Woodsreef Chrysotile Mine, New South Wales, Australia. Modal mineralogy was obtained by Rietveld refinements of data collected with an inXitu Terra portable XRD. The Partial Or No Known Crystal Structures (PONKCS) method was used to account for turbostratic stacking disorder in serpentine minerals, which are the dominant phases in tailings from Woodsreef. Weighed mixtures of synthetic tailings were made to evaluate the precision and accuracy of quantitative phase analysis using the portable instrument. An average absolute deviation (bias) of 8.2 wt% from the actual composition of the synthetic tailings was found using the portable instrument. This is comparable to the bias obtained using a laboratory-based diffractometer (9.6 wt% absolute) and to the results from previous quantitative XRD studies involving serpentine minerals. The methodology developed using the synthetic tailings was then applied to natural tailings samples from Woodsreef. Surface crusts forming on the tailings pile were found to contain hydromagnesite (∼5.8 wt%) and pyroaurite (∼2.1 wt%). Comparable results were obtained using the laboratory-based instrument and these results are expected to have similar biases to the analyses of the synthetic tailings. These findings demonstrate that portable XRD instruments may be used for field-based measurement of carbon sequestration in minerals in engineered and natural environments.",
keywords = "Carbon accounting, carbon mineralization, carbon sequestration, chrysotile, hydromagnesite, PONKCS method, portable X-ray diffraction, pyroaurite, Rietveld refinement",
author = "Turvey, {Connor C.} and Wilson, {Siobhan A.} and Hamilton, {Jessica L.} and Gordon Southam",
doi = "10.2138/am-2017-5953",
journal = "American Mineralogist",
publisher = "Mineralogical Society of America",
Turvey, CC, Wilson, SA, Hamilton, JL & Southam, G 2017, 'Field-based accounting of CO2 sequestration in ultramafic mine wastes using portable X-ray diffraction', American Mineralogist, vol. 102, no. 6, pp. 1302-1310. https://doi.org/10.2138/am-2017-5953
Field-based accounting of CO2 sequestration in ultramafic mine wastes using portable X-ray diffraction. / Turvey, Connor C.; Wilson, Siobhan A.; Hamilton, Jessica L.; Southam, Gordon.
In: American Mineralogist, Vol. 102, No. 6, 01.06.2017, p. 1302-1310.
T1 - Field-based accounting of CO2 sequestration in ultramafic mine wastes using portable X-ray diffraction
AU - Turvey, Connor C.
AU - Wilson, Siobhan A.
AU - Hamilton, Jessica L.
AU - Southam, Gordon
N2 - Carbon mineralization, the sequestration of carbon within minerals, presents one method through which we could control rising levels of anthropogenic carbon dioxide (CO2) emissions. The mineral wastes produced by some ultramafic-hosted mines have the ability to sequester atmospheric CO2 via passive carbonation reactions. Carbon accounting in mine tailings is typically performed using laboratory-based quantitative X-ray diffraction (XRD) or thermogravimetric methods, which are used to measure the abundances of carbonate-bearing minerals such as hydromagnesite [Mg5(CO3)4(OH)2·4H2O] and pyroaurite [Mg6 Fe23+ $\text{Fe}^{3+}-{2}$ (CO3)(OH)16·4H2O]. The recent development of portable XRD instruments now allows for the characterization and quantification of minerals in the field. Here we assess the feasibility of using a portable XRD instrument for field-based carbon accounting in tailings from the Woodsreef Chrysotile Mine, New South Wales, Australia. Modal mineralogy was obtained by Rietveld refinements of data collected with an inXitu Terra portable XRD. The Partial Or No Known Crystal Structures (PONKCS) method was used to account for turbostratic stacking disorder in serpentine minerals, which are the dominant phases in tailings from Woodsreef. Weighed mixtures of synthetic tailings were made to evaluate the precision and accuracy of quantitative phase analysis using the portable instrument. An average absolute deviation (bias) of 8.2 wt% from the actual composition of the synthetic tailings was found using the portable instrument. This is comparable to the bias obtained using a laboratory-based diffractometer (9.6 wt% absolute) and to the results from previous quantitative XRD studies involving serpentine minerals. The methodology developed using the synthetic tailings was then applied to natural tailings samples from Woodsreef. Surface crusts forming on the tailings pile were found to contain hydromagnesite (∼5.8 wt%) and pyroaurite (∼2.1 wt%). Comparable results were obtained using the laboratory-based instrument and these results are expected to have similar biases to the analyses of the synthetic tailings. These findings demonstrate that portable XRD instruments may be used for field-based measurement of carbon sequestration in minerals in engineered and natural environments.
AB - Carbon mineralization, the sequestration of carbon within minerals, presents one method through which we could control rising levels of anthropogenic carbon dioxide (CO2) emissions. The mineral wastes produced by some ultramafic-hosted mines have the ability to sequester atmospheric CO2 via passive carbonation reactions. Carbon accounting in mine tailings is typically performed using laboratory-based quantitative X-ray diffraction (XRD) or thermogravimetric methods, which are used to measure the abundances of carbonate-bearing minerals such as hydromagnesite [Mg5(CO3)4(OH)2·4H2O] and pyroaurite [Mg6 Fe23+ $\text{Fe}^{3+}-{2}$ (CO3)(OH)16·4H2O]. The recent development of portable XRD instruments now allows for the characterization and quantification of minerals in the field. Here we assess the feasibility of using a portable XRD instrument for field-based carbon accounting in tailings from the Woodsreef Chrysotile Mine, New South Wales, Australia. Modal mineralogy was obtained by Rietveld refinements of data collected with an inXitu Terra portable XRD. The Partial Or No Known Crystal Structures (PONKCS) method was used to account for turbostratic stacking disorder in serpentine minerals, which are the dominant phases in tailings from Woodsreef. Weighed mixtures of synthetic tailings were made to evaluate the precision and accuracy of quantitative phase analysis using the portable instrument. An average absolute deviation (bias) of 8.2 wt% from the actual composition of the synthetic tailings was found using the portable instrument. This is comparable to the bias obtained using a laboratory-based diffractometer (9.6 wt% absolute) and to the results from previous quantitative XRD studies involving serpentine minerals. The methodology developed using the synthetic tailings was then applied to natural tailings samples from Woodsreef. Surface crusts forming on the tailings pile were found to contain hydromagnesite (∼5.8 wt%) and pyroaurite (∼2.1 wt%). Comparable results were obtained using the laboratory-based instrument and these results are expected to have similar biases to the analyses of the synthetic tailings. These findings demonstrate that portable XRD instruments may be used for field-based measurement of carbon sequestration in minerals in engineered and natural environments.
KW - Carbon accounting
KW - carbon mineralization
KW - carbon sequestration
KW - chrysotile
KW - hydromagnesite
KW - PONKCS method
KW - portable X-ray diffraction
KW - pyroaurite
KW - Rietveld refinement
U2 - 10.2138/am-2017-5953
DO - 10.2138/am-2017-5953
JO - American Mineralogist
JF - American Mineralogist
Turvey CC, Wilson SA, Hamilton JL, Southam G. Field-based accounting of CO2 sequestration in ultramafic mine wastes using portable X-ray diffraction. American Mineralogist. 2017 Jun 1;102(6):1302-1310. https://doi.org/10.2138/am-2017-5953