Use of CO2 to Cure Steel Slag and Gypsum-Based Material

Xue Wang,Wen Ni,Wentao Hu,Jiajie Li,Keqing Li,Siqi Zhang

doi:10.3390/en14165174

Abstract

To improve the utilization of steel slag (SS) in CO2 capture and making building materials, the paper mainly discussed the effects of desulphurization gypsum (DG) and w/s ratio on strength development and CO2 capture capability of high Al content SS. It showed that 10 wt% DG enhanced the strength of hydration-curing SS by 262% at 28 days. Similarly, adding 6 wt% DG in carbonation-curing SS contributed to increases in strength and CO2 uptake by 283% and 33.54%, reaching 42.68 MPa and 19.12%, respectively. Strength decreases and CO2 uptake increases with w/s. Microanalysis (QXRD, SEM-EDS, TG-DTG, FTIR, XPS, and MIP) revealed that the main hydration products of SS were C-S-H gel and C4AH13, which transformed to ettringite with DG addition. The carbonation products were mainly calcite and aragonite. Additionally, the amount of aragonite, mechanically weaker than calcite, decreased and calcite increased significantly when DG was added in carbonation-curing samples, providing a denser structure and higher strength than those without DG. Furthermore, high Al 2p binding energies revealed the formation of monocarboaluminate in the DG-added carbonation samples, corresponding to higher CO2 uptake. This study provides guidance for the preparation of SS-DG carbide building materials.

Highlights

Owing to climate change and its effects on humans and their environment, there is an urgent need to reduce greenhouse gas emissions [1,2,3,4]
Mineral carbonation describes the reaction of Ca and Mg-silicate minerals with atmospheric CO2, which leads to the precipitation of carbonates
It is obvious that the non‐carbonated samples (U1, U4, and U7) tended to have much lower strengths than the non-carbonated samples (U1, U4, and U7) tended to have much strengths thecuring corresponding hydration‐carbonation‐cured samples (C1, C4,lower and C7)

Summary

Introduction

Owing to climate change and its effects on humans and their environment, there is an urgent need to reduce greenhouse gas emissions [1,2,3,4]. Mineral carbonation is thought to be a permanent form of CO2 capture due to the high stability of formed carbonates [4]. Mg-silicate minerals tend to have low carbon reactivity so that requires high temperature and high CO2 pressure, which consumes relatively large amounts of energy and releases relatively large amounts of CO2 into the atmosphere [4]. The carbon curing treatment on alkaline industrial wastes has been developed greatly for building materials making and CO2 capture. CO2 concentration and pressure, temperature, relative humidity, reaction duration, w/s (water/solid mass ratio), additive, and particle size of carbon capture feedstock are influencing factors [5]. Due to the high reactivity of solid wastes and for energy saving purposes, room temperature is mostly used in the studies. Most of the research revealed that carbon curing helped enhance the mechanical properties of the samples and their resistance to the environment [10]

Methods

Results

Conclusion