Direct aqueous mineral carbonation of secondary materials for carbon dioxide storage.

Mineral carbonation of secondary materials offers an innovative way of storing carbon dioxide in materials that instead would mostly go to waste. This study investigates the carbonation efficiency (CE) of 11 different secondaries from refractory production, waste incineration, and the paper industry compared to untreated and thermally activated serpentinite. To determine the chemical and mineralogical composition of the materials, various analytical methods, like X-ray fluorescence, X-ray diffraction, scanning electron microscopy, Brunauer-Emmet-Teller and thermogravimetric analysis have been employed, both before and after the direct aqueous carbonation process. Each material was examined over reaction times of 6 & 10 hours at 180 °C and a starting pressure of 20 bar in a 0.6 L stainless steel batch reactor. The received results were then compared to the theoretical CO 2 uptake, defined as the maximum carbon dioxide storage potential achievable if all Ca, Fe and Mg ions were converted to carbonates. The findings indicate carbonation efficiencies of 14–65 % for secondary materials, compared to 0.7–14 % observed in the serpentinite samples. The highest uptakes were achieved by the refractory materials, primarily due to their high metal oxide content. However, a negative impact was observed from graphite-based carbon binders in the refractories, with increased leaching of these binders leading to a decrease in carbonation efficiency. Materials with higher SiO 2 content showed reduced performance, suggesting a passivation layer buildup during carbonation. • The study assesses secondary raw materials, like refractory residues, for CO₂ sequestration using mineralogical analysis • Compares carbonation efficiency of 11 Mg- and Ca-rich industrial wastes with serpentinite as a benchmark. • Uses XRF, XRD, SEM, TGA, and BET analyses to study chemical composition and structural traits tied to carbonation. • Provides new insights on refractory materials' potential for carbonation and CO₂ sequestration. [ABSTRACT FROM AUTHOR]