Failure Analysis of Leakage in the Decomposition Tank of Bayer Process for Producing Alumina

• Published in: Journal of failure analysis and prevention Vol. 24; no. 4; pp. 1689 - 1698
• Main Authors: Wei, Yuwei, Ju, Chengwei, Huang, Qinghua, Du, Liang, Zhong, Linzhi, Zheng, Yunqin, Yao, Yangming, Tao, Jiahao, Wang, Zhipeng, Liu, Xi, Wu, Weiying
• Format: Journal Article
• Language: English
• Published: Materials Park Springer Nature B.V 01.08.2024
• Subjects: Aluminum oxide; Anodic dissolution; Bayer process; Corrosion environments; Corrosion mechanisms; Corrosion products; Corrosion tests; Cracks; Decomposition; Dissolution; Electrochemical corrosion; Failure analysis; Grain boundaries; Intergranular corrosion; Leakage; Microstructure; Optical microscopes; Pearlite; Stress corrosion cracking; Stress cracking; Thick walls
• ISSN: 1547-7029; 1864-1245
• DOI: 10.1007/s11668-024-01949-z

A large batch of cracks appeared in and around the welds of alumina-decomposition tank used in production of alumina by Bayer process. The crack morphology and metallographic structure were analyzed by means of SEM, EDS and optical microscope. As a crack source, pores expanded along grain boundaries and pearlite under the promotion of stresses to form final cracks in alkaline environment, resulting in leakage. The multi-stress cracking mechanism in alkaline environment is strain induced-anodic dissolution. IGPSCC (intergranular pearlitic stress corrosion crack) electrochemical corrosion model for alkali embrittlement of thick wall tank welds is established, which provides a reference for the study of weld cracking in alumina-decomposition tank after long-term operation.