Preparation sequences and pretreatment optimization of alkali-activated red mud and blast furnace slag-based materials
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ORIGINAL ARTICLE
Preparation sequences and pretreatment optimization of alkali‑activated red mud and blast furnace slag‑based materials Xiangzhou Liang1,2 · Yongsheng Ji1,3 Received: 23 May 2020 / Accepted: 30 September 2020 © Springer Japan KK, part of Springer Nature 2020
Abstract The preparation of alkali-activated materials from red mud for building materials is a promising way to solve the environmental pollution caused by red mud. However, the low compressive strength of alkali-activated red mud-based materials is the biggest obstacle to this solution. In this paper, we illustrate that the compressive strength of alkali-activated red mud and blast furnace slag-based materials is strongly influenced by the modulus of sodium silicate, preparation sequence, and calcination pretreatment. Thus, the best sodium silicate modulus (1.0) and optimized preparation sequence that involved using a cooled sodium hydroxide solution mixed with the red mud-blast furnace slag mixture before exposure to the sodium Csilicate were adopted. Then the calcination pretreatment of the red mud, gypsum, and lime was adopted to improve the compressive strength, and the optimal calcination temperature was selected to be 700 °C. The increase in the compressive strength (up to 71.82 MPa) resulted from a large number of active particles, which were generated by the fracture of numerous Si–O bonds and Al–O bonds after the calcination pretreatment. The results support the extensive utilization of red mud in building materials to prevent environmental pollution. Keywords Red mud · Alkali-activated materials · Preparation sequences · Calcination temperature · Compressive strength Abbreviations RM Red mud AAM Alkali-activated materials MSWI Municipal solid waste incinerator ARBM Alkali-activated red mud and blast furnace slag-based materials SEM Scanning electron microscope XRD Diffraction of X-rays TG–DTA Thermogravimetric analysis and differential thermal analysis XRF X-ray fluorescence spectrometer BFS Blast furnace slag * Yongsheng Ji [email protected] 1
Jiangsu Key Laboratory of Environmental Impact and Structural Safety in Engineering, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
2
Jiangsu Collaborative Innovation Center for Building Energy Saving and Construction Technology, Xuzhou 221116, Jiangsu, China
3
State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
RLG Red mud, lime, and gypsum LOI Loss on ignition
Introduction Red mud (RM) that is characterized by a high water content and complex composition with a varying bauxite composition, production process, dehydration, and storage period is a hazardous solid waste by-product of alumina production with strong alkalinity. RM can be divided into three kinds according to the production method of alumina: the sintering method, combination method, and Bayer method. The Bayer process production method is mainly used to produce RM worldwide, w
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