Accelerated Weathering and Carbonation (Mild to Intensified) of Natural Canadian Silicates (Kimberlite and Wollastonite) for CO 2 Sequestration

• Published in: Crystals
• Main Authors: Ye Eun Chai, Salma Chalouati, Hugo Fantucci, Rafael M. Santos
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2021
• Subjects: carbon sequestration; CO 2 mineralization; natural silicates; mining residues; solid carbonates; Crystallography; QD901-999; Northwest Territories
• Online Access: https://doi.org/10.3390/cryst11121584; https://doaj.org/article/331dedc82024498297af2a0ef24ea3cc

Canada’s mineral reserves can play a very important role in curbing climate change if natural alkaline minerals are used for the process of mineral carbonation. In this work, the potential of using two Canadian natural silicates for accelerated carbonation is experimentally assessed: kimberlite mine tailing (Mg 0.846 Al 0.165 Fe 0.147 Ca 0.067 SiO 3.381 ) from the Northwest Territories, and mined wollastonite ore (Ca 0.609 Mg 0.132 Al 0.091 Fe 0.024 SiO 2.914 ) from Ontario. The aim of this work was to evaluate the weathering reactivity and CO 2 uptake capacity via carbonation of these two comminuted rocks, both of which are made up of a mixture of alkaline minerals, under process conditions that spanned from milder to intensified. Research questions addressed include: does kimberlite contain a sufficient amount of reactive minerals to act as an effective carbon sink; is dehydroxylation necessary to activate kimberlite, and to what extent does it do this; do secondary phases of wollastonite hinder its reactivity; and can either of these minerals be carbonated without pH buffering, or only weathered? Incubator, slurry, and pressurized slurry methods of accelerated weathering and carbonation were used, and the effect of the process parameters (temperature, solid-to-liquid ration, reaction time, CO 2 level, pH buffer) on the CO 2 uptake and crystalline carbonates formation is tested. The reacted samples were analyzed by pH test, loss-on-ignition test, calcimeter test, and X-ray diffraction analysis. Results showed that wollastonite ore (rich in fast-weathering CaSiO 3 ) is more suitable for accelerated carbonation than kimberlite tailing (containing slow-weathering hydrated magnesium silicates and aluminosilicates) when only its capability to rapidly form solid carbonates is considered. Incubator and pressurized buffered slurry methods proved to be most effective as under these conditions the precipitation of carbonates was more favorable, while the unbuffered slurry reaction conditions were more akin to ...