Feasibility of preparing red mud-based cementitious materials: Synergistic utilization of industrial solid waste, waste heat, and tail gas

Abstract

In order to address the environmental problems caused by red mud and other industrial by-products, a new concept was proposed to use red mud to prepare cementitious materials by incorporating other solid wastes, waste heat, and tail gas. The feasibility of this synergistic concept was verified by laboratory-scale tests, and the effect of tail gas and waste heat on solid wastes was revealed by FTIR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), and SEM-EDS (Scanning electron microscopy-Energy Dispersive Spectroscopy), and the key device for carbonation disposal was developed. The results showed that the cementitious reactivity of industrial solid wastes can be improved by carbonation disposal of tail gas. The cementitious reactivity of Sintered red mud, coal gangue, fly ash, and Bayer red mud was increased by 49.8%, 4.4%, 9.5% and 18.9%, respectively. The multi-solid waste system with Bayer red mud, steel slag, carbide slag, aluminum ash, and flue gas desulfurization gypsum can generate high performance red mud-based cementitious materials (RCM) with a compressive strength of 8.8 MPa at 1 d under the circumstance of high temperature disposal. And RCM consists of 2CaO·SiO2, 3CaO·Al2O3, and CaO·(Al2O3 + Fe2O3). In addition, the mechanical strength and soundness of RCM can be improved by the carbonation of tail gas. This innovative concept provides a way for the mass utilization of red mud along with other solid wastes, waste heat and tail gas through the relevant cementitious materials for use in transportation construction, and shed light on the cleaner production of industry.