Geochemical and mineralogical constraints in iron ore tailings limit soil formation for direct phytostabilization

Songlin Wu, Yunjia Liu, Gordon Southam, Lachlan Robertson, Tsz Ho Chiu, Adam T. Cross, Kingsley W. Dixon, Jason C. Stevens, Hongtao Zhong, Ting Shan Chan, Ying Jui Lu, Longbin Huang

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Abstract

The present study aimed to characterize key physico-chemical and mineralogical attributes of magnetite iron (Fe) ore tailings to identify potential constraints limiting in situ soil formation and direct phytostabilization. Tailings of different age, together with undisturbed local native soils, were sampled from a magnetite mine in Western Australia. Tailings were extremely alkaline (pH > 9.0), with a lack of water stable aggregate and organic matter, and contained abundant primary minerals including mica (e.g., biotite), with low specific surface area (N2-BET around 1.2 m2 g−1). These conditions remained relatively unchanged after four years’ aging under field conditions. Chemical extraction and spectroscopic analysis [e.g., X-ray diffraction (XRD) and synchrotron-based Fe K edge X-ray absorption fine structure spectroscopy (XAFS) analysis] revealed that the aging process decreased biotite-like minerals, but increased hematite and magnetite in the tailings. However, the aged tailings lacked goethite, a compound abundant in natural soils. Examination using backscattered-scanning electron microscope - energy dispersive X-ray spectrometry (BSE-SEM-EDS) revealed that aged tailings contained discrete sharp edged Fe-bearing minerals that did not physically integrate with other minerals (e.g., Si/Al bearing minerals). In contrast, Fe minerals in native soils appeared randomly distributed and closely amassed with Si/Al rich phyllosilicates, with highly eroded edges. The lack of labile organic matter and the persistence of alkaline-saline conditions may have significantly hindered the bioweathering of Fe-minerals and the biogenic formation of secondary Fe-minerals in tailings. However, there is signature that a native pioneer plant, Maireana brevifolia can facilitate the bioweathering of Fe-bearing minerals in tailings. We propose that eco-engineering inputs like organic carbon accumulation, together with the introduction of functional microbes and pioneer plants, should be adopted to accelerate bioweathering of Fe-bearing minerals as a priority for initiating in situ soil formation in the Fe ore tailings.

LanguageEnglish
Pages192-202
Number of pages11
JournalScience of the Total Environment
Volume651
DOIs
Publication statusPublished - 15 Feb 2019

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Ore tailings
Iron ores
iron ore
tailings
Minerals
Tailings
Soils
Bearings (structural)
mineral
Ferrosoferric Oxide
Magnetite
magnetite
biotite
Biological materials
Aging of materials
X ray absorption fine structure spectroscopy
soil formation
organic matter
soil
secondary mineral

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Wu, Songlin ; Liu, Yunjia ; Southam, Gordon ; Robertson, Lachlan ; Chiu, Tsz Ho ; Cross, Adam T. ; Dixon, Kingsley W. ; Stevens, Jason C. ; Zhong, Hongtao ; Chan, Ting Shan ; Lu, Ying Jui ; Huang, Longbin. / Geochemical and mineralogical constraints in iron ore tailings limit soil formation for direct phytostabilization. In: Science of the Total Environment. 2019 ; Vol. 651. pp. 192-202.
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title = "Geochemical and mineralogical constraints in iron ore tailings limit soil formation for direct phytostabilization",
abstract = "The present study aimed to characterize key physico-chemical and mineralogical attributes of magnetite iron (Fe) ore tailings to identify potential constraints limiting in situ soil formation and direct phytostabilization. Tailings of different age, together with undisturbed local native soils, were sampled from a magnetite mine in Western Australia. Tailings were extremely alkaline (pH > 9.0), with a lack of water stable aggregate and organic matter, and contained abundant primary minerals including mica (e.g., biotite), with low specific surface area (N2-BET around 1.2 m2 g−1). These conditions remained relatively unchanged after four years’ aging under field conditions. Chemical extraction and spectroscopic analysis [e.g., X-ray diffraction (XRD) and synchrotron-based Fe K edge X-ray absorption fine structure spectroscopy (XAFS) analysis] revealed that the aging process decreased biotite-like minerals, but increased hematite and magnetite in the tailings. However, the aged tailings lacked goethite, a compound abundant in natural soils. Examination using backscattered-scanning electron microscope - energy dispersive X-ray spectrometry (BSE-SEM-EDS) revealed that aged tailings contained discrete sharp edged Fe-bearing minerals that did not physically integrate with other minerals (e.g., Si/Al bearing minerals). In contrast, Fe minerals in native soils appeared randomly distributed and closely amassed with Si/Al rich phyllosilicates, with highly eroded edges. The lack of labile organic matter and the persistence of alkaline-saline conditions may have significantly hindered the bioweathering of Fe-minerals and the biogenic formation of secondary Fe-minerals in tailings. However, there is signature that a native pioneer plant, Maireana brevifolia can facilitate the bioweathering of Fe-bearing minerals in tailings. We propose that eco-engineering inputs like organic carbon accumulation, together with the introduction of functional microbes and pioneer plants, should be adopted to accelerate bioweathering of Fe-bearing minerals as a priority for initiating in situ soil formation in the Fe ore tailings.",
keywords = "Fe (oxy)hydroxides, Fe-ore tailings, Mine-site rehabilitation, Mineral bioweathering, Soil structure",
author = "Songlin Wu and Yunjia Liu and Gordon Southam and Lachlan Robertson and Chiu, {Tsz Ho} and Cross, {Adam T.} and Dixon, {Kingsley W.} and Stevens, {Jason C.} and Hongtao Zhong and Chan, {Ting Shan} and Lu, {Ying Jui} and Longbin Huang",
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Wu, S, Liu, Y, Southam, G, Robertson, L, Chiu, TH, Cross, AT, Dixon, KW, Stevens, JC, Zhong, H, Chan, TS, Lu, YJ & Huang, L 2019, 'Geochemical and mineralogical constraints in iron ore tailings limit soil formation for direct phytostabilization' Science of the Total Environment, vol. 651, pp. 192-202. https://doi.org/10.1016/j.scitotenv.2018.09.171

Geochemical and mineralogical constraints in iron ore tailings limit soil formation for direct phytostabilization. / Wu, Songlin; Liu, Yunjia; Southam, Gordon; Robertson, Lachlan; Chiu, Tsz Ho; Cross, Adam T.; Dixon, Kingsley W.; Stevens, Jason C.; Zhong, Hongtao; Chan, Ting Shan; Lu, Ying Jui; Huang, Longbin.

In: Science of the Total Environment, Vol. 651, 15.02.2019, p. 192-202.

Research output: Contribution to journalArticle

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T1 - Geochemical and mineralogical constraints in iron ore tailings limit soil formation for direct phytostabilization

AU - Wu, Songlin

AU - Liu, Yunjia

AU - Southam, Gordon

AU - Robertson, Lachlan

AU - Chiu, Tsz Ho

AU - Cross, Adam T.

AU - Dixon, Kingsley W.

AU - Stevens, Jason C.

AU - Zhong, Hongtao

AU - Chan, Ting Shan

AU - Lu, Ying Jui

AU - Huang, Longbin

PY - 2019/2/15

Y1 - 2019/2/15

N2 - The present study aimed to characterize key physico-chemical and mineralogical attributes of magnetite iron (Fe) ore tailings to identify potential constraints limiting in situ soil formation and direct phytostabilization. Tailings of different age, together with undisturbed local native soils, were sampled from a magnetite mine in Western Australia. Tailings were extremely alkaline (pH > 9.0), with a lack of water stable aggregate and organic matter, and contained abundant primary minerals including mica (e.g., biotite), with low specific surface area (N2-BET around 1.2 m2 g−1). These conditions remained relatively unchanged after four years’ aging under field conditions. Chemical extraction and spectroscopic analysis [e.g., X-ray diffraction (XRD) and synchrotron-based Fe K edge X-ray absorption fine structure spectroscopy (XAFS) analysis] revealed that the aging process decreased biotite-like minerals, but increased hematite and magnetite in the tailings. However, the aged tailings lacked goethite, a compound abundant in natural soils. Examination using backscattered-scanning electron microscope - energy dispersive X-ray spectrometry (BSE-SEM-EDS) revealed that aged tailings contained discrete sharp edged Fe-bearing minerals that did not physically integrate with other minerals (e.g., Si/Al bearing minerals). In contrast, Fe minerals in native soils appeared randomly distributed and closely amassed with Si/Al rich phyllosilicates, with highly eroded edges. The lack of labile organic matter and the persistence of alkaline-saline conditions may have significantly hindered the bioweathering of Fe-minerals and the biogenic formation of secondary Fe-minerals in tailings. However, there is signature that a native pioneer plant, Maireana brevifolia can facilitate the bioweathering of Fe-bearing minerals in tailings. We propose that eco-engineering inputs like organic carbon accumulation, together with the introduction of functional microbes and pioneer plants, should be adopted to accelerate bioweathering of Fe-bearing minerals as a priority for initiating in situ soil formation in the Fe ore tailings.

AB - The present study aimed to characterize key physico-chemical and mineralogical attributes of magnetite iron (Fe) ore tailings to identify potential constraints limiting in situ soil formation and direct phytostabilization. Tailings of different age, together with undisturbed local native soils, were sampled from a magnetite mine in Western Australia. Tailings were extremely alkaline (pH > 9.0), with a lack of water stable aggregate and organic matter, and contained abundant primary minerals including mica (e.g., biotite), with low specific surface area (N2-BET around 1.2 m2 g−1). These conditions remained relatively unchanged after four years’ aging under field conditions. Chemical extraction and spectroscopic analysis [e.g., X-ray diffraction (XRD) and synchrotron-based Fe K edge X-ray absorption fine structure spectroscopy (XAFS) analysis] revealed that the aging process decreased biotite-like minerals, but increased hematite and magnetite in the tailings. However, the aged tailings lacked goethite, a compound abundant in natural soils. Examination using backscattered-scanning electron microscope - energy dispersive X-ray spectrometry (BSE-SEM-EDS) revealed that aged tailings contained discrete sharp edged Fe-bearing minerals that did not physically integrate with other minerals (e.g., Si/Al bearing minerals). In contrast, Fe minerals in native soils appeared randomly distributed and closely amassed with Si/Al rich phyllosilicates, with highly eroded edges. The lack of labile organic matter and the persistence of alkaline-saline conditions may have significantly hindered the bioweathering of Fe-minerals and the biogenic formation of secondary Fe-minerals in tailings. However, there is signature that a native pioneer plant, Maireana brevifolia can facilitate the bioweathering of Fe-bearing minerals in tailings. We propose that eco-engineering inputs like organic carbon accumulation, together with the introduction of functional microbes and pioneer plants, should be adopted to accelerate bioweathering of Fe-bearing minerals as a priority for initiating in situ soil formation in the Fe ore tailings.

KW - Fe (oxy)hydroxides

KW - Fe-ore tailings

KW - Mine-site rehabilitation

KW - Mineral bioweathering

KW - Soil structure

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JO - Science of the Total Environment

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