PND and XAS Study on Mechanochemically-treated Carbon Captured Silicate Rocks

Demand is rising for critical minerals production to support electrification, driving the need for efficient carbon capture technologies in mineral processing operations. Using mechanochemistry, rocks & minerals can be made to uptake CO2. Past research used pure minerals, rich in carbonate-forming metals like Mg and Fe, to form metal carbonates. Our research has shown that mechanochemical reactions in polymineralic rocks (eg. granite, basalt) efficiently capture CO2, whether high or low in these metals. We have since shown that CO2 trapping in polymineralic rocks is not based on metal carbonate-formation; IRRAS data indicates silicon carbonates are formed. Leaching experiments found CO2 trapped in single mineral systems is soluble, whereas in polymineralic rocks is not. Further, the process alters the solubility of metals in rock, raising the prospect that this process could be used not only to capture CO2, but also to extract valuable metals. Thus, obtaining a fundamental understanding of these mechanochemical reactions is key. Using PND, we will determine the location of CO2 in the unit cell by studying the structures as they release CO2 under rising temperature. We will obtain data on how mixed metal sites in the structure are occupied, and how leaching affects this. With XAS, we will observe changes to the local environment of key metal ions, providing complementary information to resolve the location of CO2, and to understand the fate of the metal ions after leaching.