T-Capsules: Granulated mine tailings as solid CO2 adsorbents and their performance/ recyclability as secondary aggregate in concrete production

Emerging research project on the focus area Sustainable materials and systems
Focus institute: Kvantum
Faculty: Technology

The project contributes solving two major industrial challenges: 1) carbon dioxide emission and 2) depletion of construction materials.

Carbon capturing by solid adsorbent technologies is widely studied for reducing CO2 emissions from industrial flue gas. The techniques used include absorption, adsorption, membrane filtering, and chemical looping. Research and development of solid adsorbent technologies based on industrial wastes would lower the cost to synthesize porous materials for adsorption applications. Existing literature reports the possibility of alkali silicate-based adsorbents with industrial side streams such as fly ash, rice husk ash, and diatomite.

Mine tailings are one such material with high potential that is not widely studied. Among European countries, 27% of metal ores are extracted from Finland. Currently, mine tailings produced from mining activities are normally deposited in the nearby sites of the mines as ponds, posing environmental risks. Moreover, silicate tailings with major mineralogical composition (olivine, amphibole, and pyroxene) encouraging natural carbonation are largely available all over the world.

In this project, alkali activation technique will be employed to granulate the silicate mine tailings to produce monolith solid CO2 adsorbent pellets. Mine tailings based AAMs can be produced with low energy usage, exhibits good mechanical properties, and monolith form of solid adsorbents are easy to handle. Monolith porous forms of alkali-activated materials (AAM)/ geopolymers are proven to have a good capacity for CO2 capturing and are even higher than the most adsorbents tested.

Ultimately, the adsorbents produced with silicate tailings after reaching their maximum carbon capturing capacity result in the end-product, granulated, carbonated MT pellets (T-capsules) which can be a potential replacement for aggregates in concrete production.

Doctoral researcher Prince Allah
Email: Prince.Allah at oulu.fi