The production of aluminium oxide during the Bayer process - as a raw material for the aluminium industry - is done by refining the bauxite with sodium hydroxide solution. For better economic efficiency, the sodium hydroxide re-circulates in a circular pattern. Part of the highly contaminated sodium hydroxide is discharged and combusted. The particle-loaded and halogenous gases given off pass through a pre-purification process into the regenerative thermal oxidizer (RTO) that destroys all organic contaminants. The installation consists of a temperature-resistant ceramic bag house, a scrubber with quencher and the RTO itself. The existence of alkaline metals (Na, K) requires special ceramic heat exchangers that resist corrosion at high temperatures. 

Conclusion: The malodorous gas given off, loaded with solid and particulate matter, requires a robust installation that guarantees a 24/7 operation. The contamination of the gas given off with alkaline metals was a challenge that led to the development of a special ceramic heat exchanger material.