University of Oulu

Adediran, A, Yliniemi, J, Illikainen, M. Mineralogy and glass content of Fe-rich fayalite slag size fractions and their effect on alkali activation and leaching of heavy metals. Int J Ceramic Eng Sci. 2021; 00 1– 14. https://doi.org/10.1002/ces2.10107

Mineralogy and glass content of Fe-rich fayalite slag size fractions and their effect on alkali activation and leaching of heavy metals

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Author: Adediran, Adeolu1; Yliniemi, Juho1; Illikainen, Mirja1
Organizations: 1Fibre and Particle Engineering Research Unit, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.5 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe2021101551244
Language: English
Published: John Wiley & Sons, 2021
Publish Date: 2021-10-15
Description:

Abstract

Fayalite slag (FS) is an Fe-rich nonferrous metallurgy (CaO-MgO-) FeOx-SiO₂ slag originating from nickel or copper manufacturing processes, which currently is disposed to landfills or used in low-value applications. This study investigates the mineralogy and glass content of certain sized fractions of FS and how it influences the reactivity, mechanical, and microstructural properties of the alkali-activated materials produced. Water-quenched granular FS was sieved into two size fractions: namely, a fine fraction (FF) with a particle size range of 0–0.5 mm and a coarse fraction (CF) with a particle size range of 1.5–2 mm. It was then milled to a similar median particle size of 10 μm to be used as a binder precursor. The reaction kinetics of each fraction was determined via thermal analysis microcalorimeter, and the microstructural evolution and chemical composition of the binder were studied using a scanning electron microscope coupled with an energy dispersive X-ray spectroscopy. The environmental leaching behavior of both fractions before and after alkali activation was assessed according to the EN 12457–2 standard. The results showed that both fractions consisted of fayalite, magnetite crystalline phases, and MgO-SiO₂-FeOx (-CaO-Al₂O₃) glass phase. However, FF had a higher glass content (63 wt.%) in comparison to CF (39 wt.%), and, consequently, FF was more reactive under alkali activation, as evidenced by faster reaction kinetics, faster strength development, and improved microstructural properties. Alkali-activated samples had differences in the chemical compositions of their binder gels at early stages, though later, their binders became increasingly homogenous and consisted of an Na-K-Fe-Si gel with Mg, Ca, and Al as minor constituents in both samples. Additionally, the leaching behavior of potentially toxic metals and substances from precursors and alkali-activated samples prepared was below the limits set for paved structures as specified by Finnish legislation.

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Series: International journal of ceramic engineering & science
ISSN: 2578-3270
ISSN-E: 2578-3270
ISSN-L: 2578-3270
Volume: In press
DOI: 10.1002/ces2.10107
OADOI: https://oadoi.org/10.1002/ces2.10107
Type of Publication: A1 Journal article – refereed
Field of Science: 218 Environmental engineering
Subjects:
Funding: This work was done as a part of GEOBOT project supported by European Regional Development Fund (ERDF), Pohjois-Pohjanmaa Council of Oulu Region, and various companies (Boliden Harjavalta Oy, Keliber Oy, and Saint Gobain Finland Oy). Adeolu Adediran has received funding from Finnish Cultural Foundation toward his doctoral research. J. Yliniemi received funding from Academy of Finland (grant number 322786).
Academy of Finland Grant Number: 322786
Detailed Information: 322786 (Academy of Finland Funding decision)
Copyright information: © 2021 The Authors. International Journal of Ceramic Engineering & Science published by Wiley Periodicals LLC. on behalf of the American Ceramic Society. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
  https://creativecommons.org/licenses/by/4.0/