Carbonation of BOF Slag in a Rotary Kiln Reactor in View of the Scale‐Up of the Wet Route Process

Abstract

Carbonation of alkaline residues represents a potentially interesting technique for permanently storing in solid form CO2 contained in flue gas, syngas or biogas, as well as for the valorization of the residues. In particular, the wet carbonation route requires a low amount of water, does not generate wastewater and can be exploited to produce aggregates. The efficacy of this route has been demonstrated at laboratory scale. In view of its scale‐up, this study was aimed at evaluating the performance of a wet‐route carbonation process applied to Basic Oxygen Furnace (BOF) steel slag employing an operating procedure that could be adopted also at demonstrative or full scale. Dry residues were directly fed by a loading hopper into a rotary kiln reactor, in which gas containing 40% CO2 and steam were flown through. During the experiments, the flow and composition of the gas phase were continuously monitored, allowing to calculate the amount of CO2 captured from the gas phase and to compare it with the CO2 uptake of the solid product. In addition, the leaching behavior of the treated slag was assessed. The results of the tests were close to those obtained in previous experiments performed with pre‐humidified BOF slag, both with the same reactor used in this study and at laboratory scale; this suggests that this more automated wet‐route process could be employed for demonstration or full scale tests. The set up still needs to be optimized to obtain a product with physical and technical properties suitable for use as aggregate. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13140, 2019

Assessment of a Carbonation-Based CO2 Utilization Process for the Valorization of CFBC Ash

“…More details on the rotary drum reactor were reported in previous studies. 29,30 Different carbo-granulation tests were carried out in this unit, changing the operating temperature and the binder type and setting the gas feed at 1 bar and CO 2 concentration in the gas feed at 40% vol. During each test, the speed of the rotating drum was set equal to 8 rpm, the maximum value achievable by the experimental setup, and the tilt of the reactor was zero.…”

“…The length and the inner diameter of the reactor were 150 and 8 cm, respectively. More details on the rotary drum reactor were reported in previous studies. , …”

Co-treatment of Waste From Steelmaking Processes: Steel Slag-Based Carbon Capture and Storage by Mineralization

“…Direct SS carbonation, that is, the reaction of SS and CO 2 accomplished in a single reaction step, includes two-phase (direct gas-solid carbonation) and three-phases (direct aqueous carbonation) routes (Huijgen and Comans, 2005;Librandi et al, 2019). Since the year 2000, researchers have completely a number of studies on the possibility and potential of SS's carbonation for the storage of CO 2 .…”

Pressurized in situ X-ray diffraction insights into super/subcritical carbonation reaction pathways of steelmaking slags and constituent silicate minerals

“…Yet, various reasons, such as high basicity and the propensity for heavy metal leaching and pulverization [17,[19][20][21][22][23], have made the reutilization of these materials challenging. In order to improve the negative properties of steelmaking slags and enable greater opportunities for recycling, steelmaking slags have been the subject of mineral carbonation research in recent years, with the purpose of CO2 sequestration, due to the geochemical stability of alkaline earth metal carbonates, and for waste valorization [17,[24][25][26][27].…”