Use of steel slag for CO₂ capture under realistic calcium-looping conditions

Abstract

aIn this study, CaO derived from steel slag pretreated with diluted acetic acid has been tested as a dry sorbent for CO 2 capture under realistic Ca-Looping (CaL) conditions, which necessarily implies calcination under high CO 2 partial pressure and fast transitions between carbonation and calcination stages. The multicycle capture performance of the sorbent has been investigated by varying the precalcination time, carbonation/calcination residence times and with the introduction of a recarbonation stage. Results show that the sorbent can be regenerated in very short residence times at 900 C under high CO 2 partial pressure, thus reducing the calciner temperature by about 30-50 C when compared to limestone. Although the introduction of a recarbonation stage to reactivate the sorbent, as suggested in previous studies for limestone, results in a slightly enhanced capture capacity, the sorbent performance can be significantly improved if the main role of the solid-state diffusion-controlled carbonation is not dismissed. Thus, a notable enhancement of the capture capacity is achieved when the carbonation residence time is prolonged beyond just a few minutes, which suggests a critical effect of solids residence time in the carbonator on the CO 2 capture efficiency of the CaL process when integrated into a power plant.

Energy Consumption for CO2 Capture by means of the Calcium Looping Process: A Comparative Analysis using Limestone, Dolomite, and Steel Slag

“…, steel slag annual production amounts to approximately 1 Mt in the UK alone. To use it as a CaO precursor, steel slag can be pretreated with acetic acid to obtain calcium acetate [Ca(CH3COO) 2 ] . Results from TGA tests show that the decomposition of calcium acetate occurs mainly in three steps: i) an initial dehydration, which occurs from ambient temperature to approximately 250 °C; ii) calcium acetate decomposition between 300 and 450 °C to release acetone and CaCO 3 , and iii) calcination of CaCO 3 in the range from 620 to 700 °C.…”

“…To use it as a CaO precursor, steel slag can be pretreated with acetic acid to obtain calcium acetate [Ca(CH3COO) 2 ] . Results from TGA tests show that the decomposition of calcium acetate occurs mainly in three steps: i) an initial dehydration, which occurs from ambient temperature to approximately 250 °C; ii) calcium acetate decomposition between 300 and 450 °C to release acetone and CaCO 3 , and iii) calcination of CaCO 3 in the range from 620 to 700 °C. According to TGA results, the CaO‐based sorbent derived from steel slag presents a low deactivation rate at realistic CaL conditions, which would expectedly improve the CO 2 capture efficiency of the process.…”

“…However, this relevant issue has been mostly dismissed in previous works . Moreover, results from TGA tests performed at realistic CaL conditions indicate that the CO 2 capture efficiency could be improved from the use of other CaO precursors such as dolomite and steel slag with more favorable carbonation kinetics as compared to limestone.…”

“…This work analyzes the energy consumption of the CFPP–CaL integration using results from TGA tests on limestone, dolomite, and steel slag in which calcination is performed under high CO 2 partial pressure, as would be the case in the practical application for CO 2 capture in power plants. The structure of this paper is the following: first, the multicycle carbonation behavior of CaO derived from natural limestone, dolomite, and steel slag and the CFPP–CaL integration model are briefly summarized. Results from these studies are then used to evaluate the energy consumption and CO 2 capture efficiency.…”

Leaching of Metal Ions from Blast Furnace Slag by Using Aqua Regia for CO2 Mineralization

“…By this study, BFS treated by AR was confirmed to be useful for CO 2 mineralization in terms of producing high-purity CaCO 3 for industrially useful materials as fillers for paper making and for capturing CO 2 materials via the Ca-looping cycle [37]. Amorphous silica powder can be used for preparing semiconductors, as well as an adsorbent for various potential applications [29], e.g., dehumidification and elimination of toxic matter.…”