Recycling mica and carbonate-rich mine tailings in alkali-activated composites : a synergy with metakaolin
Niu, He; Abdulkareem, Mariam; Sreenivasan, Harisankar; Kantola, Anu M.; Havukainen, Jouni; Horttanainen, Mika; Telkki, Ville-Veikko; Kinnunen, Päivö; Illikainen, Mirja (2020-08-12)
He Niu, Mariam Abdulkareem, Harisankar Sreenivasan, Anu M. Kantola, Jouni Havukainen, Mika Horttanainen, Ville-Veikko Telkki, Paivo Kinnunen, Mirja Illikainen, Recycling mica and carbonate-rich mine tailings in alkali-activated composites: A synergy with metakaolin, Minerals Engineering, Volume 157, 2020, 106535, ISSN 0892-6875, https://doi.org/10.1016/j.mineng.2020.106535
© 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/).
https://creativecommons.org/licenses/by-nc-nd/4.0/
https://urn.fi/URN:NBN:fi-fe2020101484110
Tiivistelmä
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.
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