Combining ozone and ultrasound technology to remove S2- in Bayer liquor

Xuxu Wang; Jianfeng Ran; Haisheng Duan; Ying Chen; Jiaping Zhao; Shaohua Yin; Shiwei Li; Libo Zhang

doi:10.1016/j.ultsonch.2023.106684

Combining ozone and ultrasound technology to remove S^2- in Bayer liquor

Ultrason Sonochem. 2023 Dec:101:106684. doi: 10.1016/j.ultsonch.2023.106684. Epub 2023 Nov 10.

Authors

Xuxu Wang¹, Jianfeng Ran¹, Haisheng Duan², Ying Chen³, Jiaping Zhao², Shaohua Yin⁴, Shiwei Li⁵, Libo Zhang⁶

Affiliations

¹ Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, China; State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093, China.
² Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, China; State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093, China; Yunnan Wenshan Aluminum Co., Ltd., Wenshan, Yunnan 663000, China.
³ Yunnan Wenshan Aluminum Co., Ltd., Wenshan, Yunnan 663000, China.
⁴ Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, China; State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093, China. Electronic address: yinsh@kust.edu.cn.
⁵ Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, China; State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093, China. Electronic address: lswei11@163.com.
⁶ Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, China; State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093, China. Electronic address: zhanglibopaper@126.com.

Abstract

High content sulfur (S^2-) in Bayer liquor can increase alkali consumption, accelerate equipment corrosion, especially seriously affect alumina production. The removal of S^2- in Bayer liquor is studied using ultrasonic enhanced ozone method, which significantly improves the removal efficiency. Results indicate that the best removal efficiency of 93.83 % is obtained with reaction duration of 20 min, oxygen flow rate of 80 L/h, ultrasonic power of 60 W and reaction temperature of 60 °C. The comparative analysis shows that the removal efficiency of S^2- is 25.34 % higher than that of ozone (O₃) system after introducing ultrasound (US), indicating that US accelerates the mass transfer process of O₃ and increases the hydroxyl radicals (OH) content. For further explanation of the mechanism of US/O₃ system, EPR and XPS spectra are applied to analyze the content of free radical and the form of sulfur in Bayer liquor, indicating that the content of free radical in US/O₃ system is more than US and O₃ systems, and all sulfur is converted to SO₄^2- after full oxidation.

Keywords: AOPs; Bayer liquor; Desulfurization; Ultrasonic enhanced ozone.