JultikaUniversity of Oulu repository

Abstract

CO₂ levels in the atmosphere has raised concerns about its influence on climate change. At the same time, mine tailings present a significant environmental problem for the mining industry. In the existing literature, two environmentally friendly technologies, CO₂ sequestration and Alkali activation are widely employed to solve these challenges. The technologies are however decoupled. Thus, this study explores the simultaneous use of both methods to solve both environmental problems: first through CO₂ sequestration using mineral carbonation of mine tailings, and then the valorization of CO₂-treated mine tailings using alkali activation. Batch experiments were first conducted to determine the leachability of Mg–rich tailings to extract Mg and Ca for carbonation. The residues of the batch experiments were dissolved in strong alkaline solution to determine their reactivity. The results indicated that the Mg-rich tailings can serve as good feedstock for Mg and Ca cations for carbonation. The Si-rich residues obtained can be activated to form a geopolymer, according to activation test. This study reveals that alkali activation and mineral carbonation can be coupled to solve both environmental problems presented by CO₂ and mine tailings. Thus, after leaching several tons of magnesium or calcium silicates from tailing, their residues can be utilized for the formation of alkali activated products.