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

Xiao Wang, Haowen Jing, Maoliang Zhang (), Jianwei Li, Yan Ma and Liang Yan
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Xiao Wang: School of Materials Science and Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
Haowen Jing: School of Materials Science and Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
Maoliang Zhang: Henan Academy of Sciences, Zhengzhou 450046, China
Jianwei Li: Henan Academy of Sciences, Zhengzhou 450046, China
Yan Ma: Henan Academy of Sciences, Zhengzhou 450046, China
Liang Yan: School of Materials Science and Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, China

Sustainability, 2023, vol. 15, issue 17, 1-13

Abstract: 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 (Na 8 (AlSiO 4 ) 6 (OH) 2 (H 2 O) 2 ) in the form of Si-O-Na or Al-O-Na. K is deposited in the shelf silico-oxygen void of potassium feldspar (KAlSi 3 O 8 ) 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, Ca 2+ ions can enter the internal voids of the hydroxyl sodalite and potassium feldspar silica skeleton and then replace Al 3+ 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.

Keywords: red mud dealkalization; hydroxy sodalite; potassium feldspar; silica tetrahedron network structure; reuse red mud; island-like silica tetrahedron (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2023
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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