Elsevier

Minerals Engineering

Volume 158, 1 November 2020, 106587
Minerals Engineering

Upcycling of mechanically treated silicate mine tailings as alkali activated binders

https://doi.org/10.1016/j.mineng.2020.106587Get rights and content
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Highlights

  • Silicate tailings were mechanically treated by milling at different duration (1–16 min).

  • Grinding does not influence the tremolite mineral in silicate tailings.

  • Mechanical activation improved the reactivity of tailings to be used as a precursor for alkali activation.

  • Magnesium rich tailings resulted in hydrotalcite with alkali activation.

  • Zeolite, CSH/CASH are major phases in aluminum rich tailings with combined mechanical and alkali activation.

Abstract

Mining activity is inevitable in human societies, and thus, disposal of mining waste in a proper and effective way is crucial to preserving our environment. In this context, studies on the reuse potential for mine tailings in the construction sector are booming. However, utilizing tailings as binder material is complicated due to the high variation in mineralogical composition and the low reactivity of these materials. In this study, an attempt was made to understand the effect of mechanical treatment on silicate mine tailings in order to improve their properties for use as a sole precursor in alkali-activated binders. Two different silicate tailings from Finland were studied: one rich in tremolite, which is high in magnesium (HM tailings) and one rich in anorthite and epidote, which is high in aluminum (HA tailings). Interestingly, grinding activity performed at different durations affected the properties of the tailings with various intensities, including their mineralogical and physical properties and characteristics and, thus the reactivity of tailings. Tremolite does not respond to milling for longer durations, and layered anorthite was easily distorted by the mechanical disturbance. Irrespective of the type of tailings, the compressive strength of alkali-activated milled tailings increased with an increase in grinding time from 1 to 16 min. However, the percentage of compressive strength increase varied with the type of tailings and their mineralogy.

Keywords

Mine tailings
Silicate tailings
Mechanical activation
Milling
Alkali activation

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