Integrated CO₂ Fixation, Waste Stabilization, and Product Utilization via High-Gravity Carbonation Process Exemplified by Circular Fluidized Bed Fly Ash

Abstract

The valorization of industrial solid wastes in civil engineering is one of the main routes for enhancing resource cycle toward environmental and social sustainability. In this study, an integrated approach to capturing CO2 in flue gas and stabilizing solid wastes for utilization as supplementary cementitious material via a high-gravity carbonation (HiGCarb) process was proposed. The fly ash (FA) generated from a circular fluidized bed boiler in the petrochemical industry was used. The effect of different operating parameters on the carbonation conversion was evaluated by the response surface methodology. The maximal carbonation conversion of FA was 77.2% at a rotation speed of 743 rpm and an L/S ratio of 18.9 at 57.3 °C. In addition, the workability, strength development, and durability of the blended cement with different substitution ratios (i.e., 10%, 15%, and 20%) of carbonated FA were evaluated. The results indicated that cement with carbonated FA exhibited superior properties, e.g., initial compressive strength (3400 psi at 7 d in 10% substitution ratio) and durability (autoclave expansion <0.15%) compared to cement with fresh FA. After HiGCarb, the physico-chemical properties of FA were upgraded, e.g., lower heavy-metal leaching and stabilized volume expansion, which were beneficial to usage as green materials in construction engineering.

Deployment of Accelerated Carbonation Using Alkaline Solid Wastes for Carbon Mineralization and Utilization Toward a Circular Economy

“…Meanwhile, the process chemistry, 8 reaction kinetics, 9,16 and mass transfer 14 of the HiGCarb process have been investigated in previous studies. On-site experiments were carried out at steelmaking 17 and petrochemical 18 industries to evaluate the effect of various operating parameters on the engineering performance of the HiGCarb process. Moreover, the use of the carbonated product as SCM in cement mortar was carried out, where the strength and durability of blended cement were improved in the cases of carbonated BOFS 17 and carbonated fly ash.…”

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

“…These reactions could enhance hydration heat and offer mechanical strength to the cement (especially for the initial strength development). 37,38 Therefore, the blended cement with carbonated PCFA could generally exhibit superior compressive strength compared to that of fresh PCFA.…”

CO2 Mineralization and Utilization using Steel Slag for Establishing a Waste-to-Resource Supply Chain

“…It is noted that the compressive strength of cement is determined by the mineralogical composition of mortar, such as Ca 3 SiO 5 (C 3 S), Ca 2 SiO 4 (C 2 S), Ca 3 Al 2 O 6 (C 3 A), and Ca 4 Al 2 Fe 2 O 10 (C 4 AF). For instance, triclinic (C 3 S) contributes to the initial strength development for the early 28 days, while dicalcium silicate (C 2 S) contributes to the ultimate strength for at least one year 25 . Tricalcium aluminate (C 3 A) provides strength for the early stage hydration but few for late stage.…”