Tailings after Iron Extraction in Bayer Red Mud by Biomass Reduction: Pozzolanic Activity and Hydration Characteristics

Wang, Yaguang; Liu, Xiaoming; Li, Yong; Li, Dongsheng; Zhang, Wei; Yang, Xue

doi:10.3390/ma14143955

Cited by 13 publications

(6 citation statements)

References 27 publications

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“…It is well known that cement hydration can generate large amounts of Ca(OH) 2 , but Ca(OH) 2 was not found in the XRD pattern. This means that the Ca(OH) 2 has been consumed by the pozzolanic activity of slag and red mud [ 29 , 30 ].…”

Section: Resultsmentioning

confidence: 99%

Microstructure and Key Properties of Phosphogypsum-Red Mud-Slag Composite Cementitious Materials

Chen²,

Lin

et al. 2022

Materials

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Due to the low content of silicon and aluminum in red mud and the low reaction activity of red mud, when it was used to prepare composite cementitious materials, it was necessary to assist other aluminosilicates and improve their activity by certain methods. In this study, it was proposed to add slag to increase the percentage of silicon and aluminum in the system, and to improve the reactivity of the system through the activation effect of sulfate in phosphogypsum. The effects of slag and phosphogypsum contents on the mechanical properties and microstructures of composite cementitious materials were studied. X-ray diffraction analysis (XRD), thermogravimetric analysis (TG-DTG), and scanning electron microscopy (SEM) were used to analyze the effects of slag and phosphogypsum contents on the hydration products, microstructure, and strength formation mechanism of composite cementitious materials. The results show that with the increase of slag, the strength of the composite cementitious material increases gradually. When the slag content is 50%, the 28-day compressive strength reaches a maximum of about 14 MPa. Compared with the composite material without phosphogypsum, the composite cementitious material with 10–20% phosphogypsum showed higher strength properties, in which the 28-day compressive strength exceeds 24 MPa. The main reason for this is that the sulfate in phosphogypsum can cause the composite cementitious material to generate a large amount of ettringite and accelerate the dissolution of red mud and slag, increasing the release of aluminates, silicates, and Ca2+ to form more C-(A)-S-H and ettringite. In addition, a large amount of C-(A)-S-H makes ettringite and unreacted particles combine into a uniform and compact structure, thus improving the strength. When the content of phosphogypsum exceeds 40%, the 28-day compressive strength of the composite cementitious material drops below 12 MPa due to the presence of fewer hydration products and the expansion of ettringite.

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Section: Resultsmentioning

confidence: 99%

Microstructure and Key Properties of Phosphogypsum-Red Mud-Slag Composite Cementitious Materials

Chen²,

Lin

et al. 2022

Materials

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“…The phase composition has an important influence on the pozzolanic activity of RM. Previous studies have shown that the amorphous phase is the most active phase in supplementary cementitious materials, such as GGBFS and fly ash [ 3 ]. The XRD patterns of RM calcined at different temperatures, as shown in Figure 1 .…”

Section: Resultsmentioning

confidence: 99%

“…Figure 6 shows the FTIR spectra of RM calcined at different temperatures. The absorption peak is 3638 cm −1 , which corresponds to the stretching vibration of free –OH [ 3 ]. The absorption peak at 3452 cm −1 corresponds to the stretching vibration of associating –OH.…”

Section: Resultsmentioning

confidence: 99%

“…Bayer red mud (RM) is a kind of strong alkaline solid waste discharged in the process of alumina production; about 1–2 tons of RM will be discharged per ton of alumina production [ 1 , 2 , 3 ]. At present, the annual discharge of RM has exceeded 100 million tons in China, which is mainly disposed of by damming, and the comprehensive utilization rate is less than 4% [ 3 ]; this stacked RM has caused serious pollution to the surrounding environment. In order to solve the problem of RM pollution, the comprehensive utilization of RM has become a focus for researchers.…”

Section: Introductionmentioning

confidence: 99%

“…RM can be used as a supplementary cementitious material for cement and concrete, which can greatly improve the resource utilization rate of RM. However, the current utilization rate of RM in cementitious materials is low because of its high alkalinity and low pozzolanic activity [ 3 ]. The pozzolanic activity of industrial solid waste is a hot topic in current research [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Rapid Evaluation of the Pozzolanic Activity of Bayer Red Mud by a Polymerization Degree Method: Correlations with Alkali Dissolution of (Si+Al) and Strength

et al. 2021

Self Cite

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A large amount of Bayer process red mud is discharged in the process of alumina production, which has caused significant pollution in the environment. The pozzolanic activity of Bayer red mud as a supplementary cementitious material is a research hotspot. In this work, a new method for Fourier-transform infrared spectrometry is used to determine the polymerization degree of Bayer red mud in order to evaluate its pozzolanic activity. Based on the results of the dissolution concentration of (Si+Al), strength index and polymerization degree of Bayer red mud, the relationships between different evaluation methods were analyzed, and the relevant calculation formulas of pozzolanic activity were obtained. The results showed that different evaluation methods can reflect the variation law of pozzolanic activity in Bayer red mud. The polymerization degree of Bayer red mud had a good linear relationship with the pozzolanic activity index obtained by the strength index and dissolution concentration of (Si+Al), respectively. The polymerization degree was negatively correlated with pozzolanic activity index and dissolution concentration of (Si+Al), and the correlation coefficients were greater than 0.85. Therefore, this method was found to be effective and hence can be used as a rapid and simple test for pozzolanic activity evaluation of Bayer red mud.

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Influence of nano-SiO2 and steel fiber on mechanical and microstructural properties of red mud-based geopolymer concrete

Long

et al. 2023

Construction and Building Materials

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Tailings after Iron Extraction in Bayer Red Mud by Biomass Reduction: Pozzolanic Activity and Hydration Characteristics

Cited by 13 publications

References 27 publications

Microstructure and Key Properties of Phosphogypsum-Red Mud-Slag Composite Cementitious Materials

Microstructure and Key Properties of Phosphogypsum-Red Mud-Slag Composite Cementitious Materials

Rapid Evaluation of the Pozzolanic Activity of Bayer Red Mud by a Polymerization Degree Method: Correlations with Alkali Dissolution of (Si+Al) and Strength

Influence of nano-SiO2 and steel fiber on mechanical and microstructural properties of red mud-based geopolymer concrete

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