An Efficient Dealkalization of Red Mud Through Microwave Roasting and Water Leaching

Zeng, Kui; Quan, Xuejun; Jiang, Qibing; Jiang, Zhanghao; Qiu, Facheng

doi:10.1007/s11837-022-05289-x

Cited by 7 publications

(2 citation statements)

References 28 publications

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“…At present, the reported methods for removing alkali metals from red mud mainly include water washing [23,28], acid neutralization [29,30], replacement [31][32][33], and salting out [34]. The alkali in red mud is divided into free alkali and chemically bound alkali.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Alkali in Bayer Red Mud: Content and Occurrence State in Different Structures

Wang,

Jing,

Zhang

et al. 2023

Sustainability

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The application of large amounts of red mud in the field of building materials is one of the main ways to reuse this material, but the high alkali content of red mud limits its application. In this paper, the washable alkali, removable alkali, and lattice alkali contents of Bayer red mud were studied, and the occurrence states of potassium and sodium in red mud were studied using XRD, IR, XPS, and NMR. On this basis, the removal mechanism for potassium and sodium in red mud was analyzed. The results showed that the Na in the red mud was mainly deposited in the shelf silicon voids of hydroxy sodalite (Na8(AlSiO4)6(OH)2(H2O)2) in the form of Si-O-Na or Al-O-Na. K is deposited in the shelf silico-oxygen void of potassium feldspar (KAlSi3O8) in the form of Si-O-K or Al-O-K. The washable Na and K contents of the mud were 13.7% and 4.47%; the alkali removal agent CaO removed 83.1% and 50.8% of Na and K in the red mud; and the lattice alkali Na and K contents were 3.20% and 44.8%, respectively. In the process of red mud dealkalization, Ca2+ ions can enter the internal voids of the hydroxyl sodalite and potassium feldspar silica skeleton and then replace Al3+ in the Si-O skeleton and Na+ and K+ in the skeleton voids. The replacement reaction changes the silica tetrahedron network structure, resulting in the disintegration of the frame-like silica tetrahedron in the hydroxyl sodalite and potassium feldspar, forming an isolated, island-like silica tetrahedron in hydrated garnet.

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Section: Introductionmentioning

confidence: 99%

Analysis of Alkali in Bayer Red Mud: Content and Occurrence State in Different Structures

Wang,

Jing,

Zhang

et al. 2023

Sustainability

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“…At present, the global reserves of red mud have reached 4.6 billion tons, of which China has accumulated more than 790 million tons. However, the comprehensive utilization rate is only 5.24% [ 5 , 7 , 8 ]. Therefore, how to improve the resource utilization of these two solid wastes is an urgent issue.…”

Section: Introductionmentioning

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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Hazard and Removal of Soluble Sodium from Red Mud Through Stepwise Recovery by Super Gravity

Lan,

Gao,

et al. 2023

JOM

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An Efficient Dealkalization of Red Mud Through Microwave Roasting and Water Leaching

Cited by 7 publications

References 28 publications

Analysis of Alkali in Bayer Red Mud: Content and Occurrence State in Different Structures

Analysis of Alkali in Bayer Red Mud: Content and Occurrence State in Different Structures

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

Hazard and Removal of Soluble Sodium from Red Mud Through Stepwise Recovery by Super Gravity

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