Elsevier

Minerals Engineering

Volume 157, 1 October 2020, 106535
Minerals Engineering

Recycling mica and carbonate-rich mine tailings in alkali-activated composites: A synergy with metakaolin

https://doi.org/10.1016/j.mineng.2020.106535Get rights and content
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Highlights

  • Valorisation of mine tailings by alkali activation.

  • Cancrinite zeolite was found in the process of alkali activation.

  • Investigation on C-(N)-A-S-H gel formation in the synergistic geopolymer.

  • Life cycle assessment of new binders indicates less environmental impact.

Abstract

The main objective of this paper was to investigate the alkali activation of mine tailings (MT) after mechanochemical activation and the effect of metakaolin (MK) addition. Finnish mica-rich tailings from a phosphate mine were studied as precursors for alkali-activated materials (AAM) with a potential application as a substitute for ordinary Portland cement (OPC). The principal physical properties (water absorption, apparent porosity and unconfined compressive strength) were measured for samples containing 30% to 70% tailings. Zeolite phases such as natrolite and cancrinite were observed and the formation of C-(N)-A-S-H1 and N-A-S-H gels was identified by XRD, DRIFT, FESEM-EDS and NMR technologies. A life cycle assessment (LCA) was conducted on specimens in comparison to OPC. This work indicated that phosphate MT can be recycled through alkali activation with lower CO2 emission compared to all-metakaolin geopolymers and that the binder phase formed at the most promising tailings contents (60– 70%) was C-(N)-A-S-H gel.

Keywords

Mine tailings
Metakaolin
Geopolymers
Gel chemistry
Life cycle assessment
Zeolite
Mechanochemical activation

Cited by (0)

1

C-CaO, N-Na2O, A-Al2O3, S-SiO2, H-H2O.