Application of clean oxidation technology using H2O2 for simultaneous removal of sulfur and organic substances in the Bayer process

• Published in: Hydrometallurgy Vol. 229; p. 106367
• Main Authors: Li, Mengnan, Liu, Zhanwei, Yan, Hengwei, Ma, Wenhui, Liu, Shuxin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2024
• Subjects: H2O2; High‑sulfur bauxite; Organic substance; S2; Simultaneous removal; Organic substance; Simultaneous removal; High‑sulfur bauxite; H2O2; S2
• ISSN: 0304-386X
• DOI: 10.1016/j.hydromet.2024.106367

The harmful effects of sulfur and organic substances pose constraints on the green and sustainable development of the Bayer process for alumina production. This research aims to develop a method that utilizes H2O2 to remove sulfur and organic substances during the digestion stage of bauxite, based on the mineralogical investigation of sulfur and organic substance. The extent of removal of S2− and total organic carbon reached 95.6% and 68.0%, respectively, under most suitable conditions of 12% H2O2 dosage, temperature of 533 K, and duration of 80 min. Based on thermodynamic calculations, it is suggested that S2− is oxidized to SO42−. Additionally, the free radical reaction mechanism of organic substances in H2O2 wet oxidation of Bayer liquor is proposed. The results confirm that this method does not introduce any impurities and does not have any impact on the digestion efficiency of alumina and the Bayer process. •This method can remove both sulfur and organic substances in the Bayer process.•H2O2 does not introduce any impurities.•S2− has been effectively oxidized to SO42−.•The free radical reaction mechanism of organic substance oxidation in alkaline solutions was elucidated.•This method will not have any adverse effects on the digestion rate of alumina.