Introducing AlumiNEXT™: the next generation in alumina refining

A/Prof Woei Saw, from the University of Adelaide's School of Chemical Engineering, is leading the AlumiNEXT™ Project, a flagship HILT CRC project to decarbonise alumina refineries.

According to the Resources and Energy Quarterly Report, June 2024, Australia is the second largest global producer of alumina, producing approximately 17 megatonnes per annum, with an export value of $8.5 billion. While the alumina industry is crucial to the global economy, it is also one of the most energy intensive industries creating a significant source of carbon emissions and is a challenging sector to transition to net-zero.

The AlumiNEXT™ Project explores innovative ways to decarbonise alumina refineries by transitioning from natural gas combustion to hydrogen or electrification in the calcination process and achieving net-zero steam generation and recovery within the Bayer Process (refining bauxite ore to produce alumina).

A/Prof Saw and his team are exploring innovative ways to decarbonise alumina processing by transitioning from natural gas combustion to electrification or hydrogen in the calcination process and achieving net-zero steam generation and recovery within the Bayer process.

The project aims to derisk relatively high technology readiness level (TRL) technologies that can be retrofitted into current refineries to reduce emissions and to develop novel technologies to create a step change in efficiency, reduced carbon emissions and cost for next-generation net-zero alumina refineries.

The Bayer process is the primary industrial method for extracting alumina (aluminum oxide) from bauxite ore. It consumes 10-12 gigajoules per tonne of alumina, which is about 25% of the natural gas consumption of Western Australia, and very significant in terms of the amount of natural gas used.

The Bayer process is the primary industrial method for extracting alumina (aluminum oxide) from bauxite ore, involving four key steps: digestion, where bauxite is mixed with hot caustic soda to dissolve the alumina; clarification, where insoluble impurities (red mud) are separated; precipitation, where aluminum hydroxide crystals are formed from the refined solution; and calcination, where these crystals are heated to over 1000°C, producing pure alumina.

The AlumiNEXT™ project is made up of two strands – a transitional pathway that aims to decarbonise the Bayer process, to be retrofitted to current refineries to reduce emissions, and a transformational pathway that will design the next generation of net zero emissions reactors.

Researchers are mapping plausible pathways to incorporate clean energy sources and to re-use the latent and waste heat generated in the high temperature calcination process to create a reference point for their industry partners for them to translate and use in their own refinery, as conditions in every aluminium plant differs.

The calcination process, which uses very high temperatures to remove water from gibbsite to convert to alumina, is very hard to decarbonise. There is a need to transition existing infrastructure to retrofit and reduce natural gas consumption with electricity and thermal energy storage. This is not a one size fits all scenario, and much research is needed to ascertain the impact on product quality in a wide range of conditions.

While some companies are interested in retrofitting, all are interested in what the next generation of alumina calciner will look like.Associate Professor Woei Saw, the University of Adelaide

About a century ago calcination began by using a rotary kiln, which was very inefficient in terms of energy efficiency and operational cost. In the 1960s the current day reactor was adopted, the standardised fluidised bed flash calciner, which improved energy efficiency, reliability and cost.

AlumiNEXT™ will revolutionise the technology, the next generation calciner that should last another 50 years or so.

“It will be a very important achievement for us. It will be expensive, but industry want a new calciner and they are ready to make the change”, A/Prof Saw says.

A lot of fundamental studies are being conducted to understand how the reactor needs to be designed, and how it will respond in different conditions. Different operating conditions will affect the design of the reactor, which will affect the whole production process.

“Understanding the kinetics and the impacts on product quality under the new calcination environment will have an impact on how we will design the reactor,” A/Prof Saw explains.

“In 2025, we are focussed on gathering experimental data. In 2026, we will be focussing on concept development of the novel calciner design and by 2027 we are aiming to have an integrated system with the novel calciner plus a heat recovery system, leading to proof of concept, a pilot-scale demonstration,” A/Prof Saw says.

The process to change the industry will take time, but to meet the 2050 net zero emissions targets it is vital work that needed to start as soon as possible (project funding was announced in 2023). The AlumiNEXT™ project is now being recognised within the alumina industry around the world as a unique HILT CRC project to decarbonise the industry. A/Prof Woei Saw and his team of researchers are working to create next generation technology that will have a major impact on reducing heavy industry carbon emissions.

More information is available from the HILT CRC website.