High-Gravity Carbonation Process for Enhancing CO₂ Fixation and Utilization Exemplified by the Steelmaking Industry

Abstract

The high-gravity carbonation process for CO2 mineralization and product utilization as a green cement was evaluated using field operation data from the steelmaking industry. The effect of key operating factors, including rotation speed, liquid-to-solid ratio, gas flow rate, and slurry flow rate, on CO2 removal efficiency was studied. The results indicated that a maximal CO2 removal of 97.3% was achieved using basic oxygen furnace slag at a gas-to-slurry ratio of 40, with a capture capacity of 165 kg of CO2 per day. In addition, the product with different carbonation conversions (i.e., 0%, 17%, and 48%) was used as supplementary cementitious materials in blended cement at various substitution ratios (i.e., 0%, 10%, and 20%). The performance of the blended cement mortar, including physicochemical properties, morphology, mineralogy, compressive strength, and autoclave soundness, was evaluated. The results indicated that the mortar with a high carbonation conversion of slag exhibited a higher mechanical strength in the early stage than pure portland cement mortar, suggesting its suitability for use as a high early strength cement. It also possessed superior soundness compared to the mortar using fresh slag. Furthermore, the optimal operating conditions of the high-gravity carbonation were determined by response surface models for maximizing CO2 removal efficiency and minimizing energy consumption.

Challenges and Perspectives on Carbon Fixation and Utilization Technologies: An Overview

“…Pang et al (2015) demonstrated that replacing non-carbonated slags with carbonated slags can result in a 20% increase in compressive strength in 28 days, as well as reduce environmental problems such as the leaching of heavy metals. A similar observation was made by Pan et al (2015c). This might be attributed to the enhanced hydration of C 3 A by CaCO 3 to form stable calcium carboaluminate (C 3 A·CaCO 3 ·11H), as described in Eq.…”

“…High micro-mixing between the slurry and gas phases enhances the overall mass transfer, thereby improving the carbonation conversion and reducing the residence time. It was noted that energy consumption for the high-gravity carbonation process, including grinding, pumps, blowers, and rotation, was estimated to be 268.6 ± 57.9 kWh t-CO 2 -1 , with 90% CO 2 removal efficiency (Pan et al, 2015c), which met the goals set by the U.S. DOE (Matuszewski et al, 2011).…”

“…The use of carbonated steelmaking slag as SCMs offers several benefits (Monkman et al, 2009;Pan et al, 2015a): (1) keep globally available industrial alkaline solid wastes out of landfills; (2) provide an economic approach to sequester CO 2 at the same time for construction use; (3) create an alternative source thereby reducing the need to transport suitable natural sands or the energy required to produce manufactured aggregates; (4) reduce the amount of leachable metals such as chromium after carbonation; and (5) reduce the amount of free CaO and its associated hydration expansion in service. Several studies have investigated the utilization of carbonated steel slag as SCMs in blended cement (Pan et al, 2015c) and a fine aggregate in concrete (Monkman et al, 2009). After carbonation, the physicochemical properties of steelmaking slag change significantly, thereby affecting the performance of blended cement.…”

Mechanistic insight into mineral carbonation and utilization in cement-based materials at solid–liquid interfaces

“…This reaction is exothermic and faster than that of C 3 S hydration. 36 The unstable phase in eqn (13) aer one day would gradually convert to the monocarbonate phase and C 3 AH 6 , as shown in eqn (14). These reactions could enhance hydration heat and offer mechanical strength to the cement (especially for the initial strength development).…”

Carbon Dioxide Sequestration via Steelmaking Slag Carbonation in Alkali Solutions: Experimental Investigation and Process Evaluation

“…The highest carbonation conversion rate obtained is approximately 72% at a reaction time of 1 h, an operating pressure of 101 kPa, and a temperature of 60°C. Pan et al [18][19][20] investigated the accelerated carbonation of steelmaking slag coupled with metalworking wastewater in a rotating packed bed and high-gravity rotating packed bed reactor. Results showed that the applied rotating packed bed or high-gravity rotating packed bed reactor can improve the mass transfer rate among phases owing to its high centrifugal force and excellent micromixing ability, thereby achieving a superior CO 2 fixation efficiency.…”