Work

Alkali-Activated CO2‑Capturing Backfill Material for Coal Mining Incorporating Municipal Solid Waste Incinerated Bottom Ash

Year: 2025

Type: article

Abstract: The ability of backfill materials to capture CO2 in coal goaf would reduce atmospheric CO2 concentrations and replace mining cement-based backfill materials to offset the considerable global CO2 emissions of ordinary Portland cement production. This study investigated the feasibility of integrating CO2 capture and backfill in coal goaf with municipal solid waste incinerated bottom ash (MSWI-BA) and granulated blast furnace slag (GBFS). The CO2 capture ability and its effect on the mechanical strength and microstructure of alkali-activated materials incorporating MSWI-BA and GBFS were studied. Carbonation depth increased with increasing MSWI-BA incorporation. After 6 h of carbonation at 65 ± 2% relative humidity and 30% CO2, alkali-activated material incorporating 40% MSWI-BA exhibited a CO2 uptake of 4.46 wt %. However, compressive strength decreased following carbonation, yet the alkali-activated material sample with the highest CO2 uptake showed 7-day, 14-day, and 28-day compressive strengths of 19.6, 20.3, and 19.7 MPa, respectively. While the surface areas and total pore volumes of carbonated samples decreased due to the formation of carbonates filling the pores, the porosity of carbonated samples incorporated with 10, 30, and 50% MSWI-BA decreased by 6.5, 14.2, and 22.2%, respectively, indicating that the carbonated MSWI-BA-incorporated sample still maintained the structural stability. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results revealed that increasing the MSWI-BA incorporation proportion resulted in more carbonates being generated. The CO2 emission index was at least 51.9% lower than ordinary Portland cement (OPC), indicating that alkali-activated materials incorporating MSWI-BA can serve as a promising green, low-carbon emission material for backfilling coal goaf to mitigate rock burst disasters and capturing CO2.

Source: ACS Omega

DOI: 10.1021/acsomega.5c01445

Authors: Guolan Dou, Tian Zhang, Gen Liu, Jingyu Wang

Institutions: China University of Mining and Technology, State Key Laboratory of Coal Mine Disaster Dynamics and Control

Language: English

Topic: Concrete and Cement Materials Research

Subfield: Civil and Structural Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Responsible consumption and production, Climate action

Open Access status: gold

Estimated APC paid: $1,935