Red mud with enhanced dealkalization performance by supercritical water technology for efficient SO2 capture

Zimeng Nie; Qun Zhao; Qilin Zhao; Yingjie Li; Dian Yang; Huaying Liu; Shupu Yang; Jie Li; Senlin Tian; Chen Li; Cheng Tie; Jianhong Huang; Ping Ning

doi:10.1016/j.jenvman.2023.118469

Red mud with enhanced dealkalization performance by supercritical water technology for efficient SO₂ capture

J Environ Manage. 2023 Oct 15:344:118469. doi: 10.1016/j.jenvman.2023.118469. Epub 2023 Jun 30.

Authors

Zimeng Nie¹, Qun Zhao², Qilin Zhao³, Yingjie Li⁴, Dian Yang⁵, Huaying Liu⁶, Shupu Yang⁷, Jie Li⁸, Senlin Tian⁹, Chen Li¹⁰, Cheng Tie¹¹, Jianhong Huang¹², Ping Ning¹³

Affiliations

¹ Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province, 650500, China. Electronic address: keita97@163.com.
² Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province, 650500, China. Electronic address: 20190073@kust.edu.cn.
³ Yunnan Environmental Monitoring Center, Kunming, Yunnan Province, 650034, China. Electronic address: 615975026@qq.com.
⁴ Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province, 650500, China. Electronic address: yjli@kmust.edu.cn.
⁵ Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province, 650500, China. Electronic address: yangdian6@sina.com.
⁶ Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province, 650500, China. Electronic address: liuhuaying86@sina.com.
⁷ Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province, 650500, China.
⁸ Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province, 650500, China. Electronic address: lj478425753@163.com.
⁹ Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province, 650500, China. Electronic address: tiansenlin@outlook.com.
¹⁰ Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province, 650500, China. Electronic address: lcshirley@163.com.
¹¹ Yunnan Environmental Monitoring Center, Kunming, Yunnan Province, 650034, China. Electronic address: 83176607@qq.com.
¹² Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province, 650500, China. Electronic address: huangjianhong78@163.com.
¹³ Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province, 650500, China. Electronic address: ningping1958@163.com.

PMID: 37393878
DOI: 10.1016/j.jenvman.2023.118469

Abstract

The total de-alkalization treatment of industrial solid waste red mud (RM) has been a worldwide challenge. Removing the insoluble structural alkali fraction from RM is the key to enhancing the sustainable utilization of RM resources. In this paper, supercritical water (SCW) and leaching agents were used for the first time to de-alkalize the Bayer RM and to remove sulfur dioxide (SO₂) from flue gas with the de-alkalized RM slurry. The results showed that the optimum alkali removal and Fe leaching rates of RM-CaO-SW slurry were 97.90 ± 0.88% and 82.70 ± 0.95%, respectively. Results confirmed that the SCW technique accelerated the disruption of (Al-O) and (Si-O) bonds and the structural disintegration of aluminosilicate minerals, facilitating the conversion of insoluble structural alkalis to soluble chemical alkalis. The exchangeable Ca²⁺ displaced Na⁺ in the remaining insoluble base, producing soluble sodium salts or alkalis. CaO consumed SiO₂, which was tightly bound to Fe₂O₃ in RM, and released Fe₂O₃, which promoted Fe leaching. RM-SCW showed the best desulfurization performance, which maintained 88.99 ± 0.0020% at 450 min, followed by RM-CaO-SW (450 min, 60.75 ± 6.00%) and RM (180 min, 88.52% ± 0.00068). The neutralization of alkaline components, the redox of metal oxides, and the liquid-phase catalytic oxidation of Fe contributed to the excellent desulfurization performance of the RM-SCW slurry. A promising approach shown in this study is beneficial to RM waste use, SO₂ pollution control, and sustainable growth of the aluminum industry.

Keywords: Dealkalization; Iron leaching; Red mud; Supercritical water; Wet slurry desulfurization.

MeSH terms

Aluminum
Industrial Waste
Oxides
Silicon Dioxide*
Water* / chemistry

Substances

Water
Silicon Dioxide
Industrial Waste
Aluminum
Oxides