Siyun completed her PhD at the School of Chemical Engineering and Advanced Materials at Adelaide University, supervised by Associate Professor Woei Saw. Siyun’s project examined whether steam vented from the Bayer circuit and calcination can be recovered and reused to reduce energy use and emissions in alumina refining. It assessed steam recovery from digestion, precipitation, evaporation and calcination, and compared compression options including multi-stage mechanical vapour recompression (MVR), thermal vapour recompression (TVR) and integrated TVR-MVR systems. The results show that MVR was the strongest-performing option assessed, and that steam-based calcination pathways – including hydrogen in oxygen–steam combustion and fully electrified calcination – improve steam recovery potential by producing high-concentration steam. For hydrogen in oxygen–steam calcination, modelled energy demand was slightly higher than conventional natural gas/air calcination, but the configuration also offered the potential to recover 2.1 GJ/tAl₂O₃ of steam enthalpy (thermal energy). For industry, the work indicates that steam recovery from calcination alone could supply 27% – 43% of Bayer steam demand, depending on the calcination pathway, while the optimised full-recovery case could potentially meet 100% of Bayer steam demand internally. In the full-recovery case, energy use for steam supply fell by 79%, from 6.64 to 1.41 GJ/tAl₂O₃, and the modelled levelised cost of decarbonised steam for the Bayer circuit fell by 50%, from US$110.2 to US$55.1 per tAl₂O₃ at 70 US$/MWh electricity, relative to gas boilers with carbon capture and storage. The thesis also notes that achieving these outcomes would require substantial capital investment in large multi-stage MVR systems. Siyun’s PhD work followed on from HILT Project RP1.007 Preliminary assessment of technical and economic feasibility of key options for low-carbon alumina calcination.