Aqueous mineral carbonation of three different industrial steel slags: Absorption capacities and product characterization

Abstract

Heavy carbon industries produce solid side stream materials that contain inorganic chemicals like Ca, Na, or Mg, and other metals such as Fe or Al. These inorganic compounds usually react efficiently with CO₂ to form stable carbonates. Therefore, using these side streams instead of virgin chemicals to capture CO₂ is an appealing approach to reduce CO₂ emissions. Herein, we performed an experimental study of the mineral carbonation potential of three industrial steel slags via aqueous, direct carbonation. To this end, we studied the absorption capacities, reaction yields, and physicochemical characteristics of the carbonated samples. The absorption capacities and the reaction yields were analyzed through experiments carried out in a reactor specifically designed to work without external stirring. As for the physicochemical characterization, we used solid-state Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM). Using this reactor, the absorption capacities were between 5.8 and 35.3 g/L and reaction yields were in the range of 81-211 kg CO₂/ton of slag. The physicochemical characterization of the solid products with solid FTIR, XRD and SEM indicated the presence of CaCO₃. This suggests that there is potential to use the carbonated products in commercial applications.

Keywords: Absorption capacity; Carbon capture; Side stream utilization; Steel slag; Transport and storage.