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Deficiencies of secondary Fe (oxy)hydroxides associated with phyllosilicates and organic carbon limit the formation of water-stable aggregates in Fe-ore tailings

Wu, Songlin ; Nguyen, Tuan A.H. ; Liu, Yunjia ; Southam, Gordon ; Wang, Shuncai ; Chan, Ting-Shan ; Lu, Ying-Rui ; Huang, Longbin

Chemical geology, 2019-09, Vol.523, p.73-87 [Periódico revisado por pares]

Elsevier B.V

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  • Título:
    Deficiencies of secondary Fe (oxy)hydroxides associated with phyllosilicates and organic carbon limit the formation of water-stable aggregates in Fe-ore tailings
  • Autor: Wu, Songlin ; Nguyen, Tuan A.H. ; Liu, Yunjia ; Southam, Gordon ; Wang, Shuncai ; Chan, Ting-Shan ; Lu, Ying-Rui ; Huang, Longbin
  • Assuntos: Aggregate stability ; Fe (oxy)hydroxides ; Iron ore tailing ; Phyllosilicates ; Spectroscopic characterization
  • É parte de: Chemical geology, 2019-09, Vol.523, p.73-87
  • Descrição: The formation of water-stable, hierarchical aggregate structure is one of the critical processes in eco-engineering iron (Fe) ore tailings into soil-like medium for sustainable rehabilitation of Fe ore mine site. Through systematically comparing physical structure and mineralogical differences between Fe ore tailings' aggregates and Fe-rich native soil aggregates at a magnetite-Fe ore mine, the present study captured the microstructure, mineralogy and organic matter composition of aggregates in aged (4 years old) tailings, in comparison with those in native soils. A suite of micro-spectroscopic methods have been employed to elucidate their physical, mineralogical and morphological characteristics, including synchrotron based Fe K edge X-ray absorption fine structure spectroscopy (XAFS), and backscattered electrons (BSE)-scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). The results revealed significant differences in physical structure of aggregates in Fe ore tailings and natural soils rich in Fe, which was attributed to their different mineralogical and organic components and characteristics. Especially, it was found that the secondary Fe (oxy)hydroxides (i.e., goethite, ferrihydrite) and their interactions with Al/Si rich secondary phyllosilicates (or aluminosilicates) were required in the formation of amorphous Fe-Si-Al rich gels that acted as cementing agents for agglomerating Si-rich particles (e.g., quartz) in soil. In contrast, tailing aggregates (rich in more crystalline primary minerals such as magnetite and biotite) lacked these gels, resulting in poor stability. Comparatively, natural soil aggregates contained more recalcitrate organic carbon groups (e.g., aromatic, carboxyl and aliphatic C) than tailing aggregates, which would have also contributed to the improvement of aggregate stability through organo-mineral associations. This study has improved our understanding of key limiting geochemical factor(s) involved in the aggregation of Fe rich soils, which would provide the basis for formulating effective eco-engineering inputs to accelerate the development of soil-like structure in the Fe ore tailings for sustainable rehabilitation. •Microstructures of aggregates within Fe ore tailings and natural Fe-rich soils were distinctly different;•Soil aggregates were bound with Fe-Si-Al rich gels from interactions between Fe (oxy)hydroxides and secondary phyllosilicates;•Tailing aggregates lacked secondary phyllosilicates and functional organic groups, hindering formation of stable aggregates;•Plant root activities facilitated water-stable aggregate formation.
  • Editor: Elsevier B.V
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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