Rio Tinto examines technical implications of using hydrogen to produce green alumina

The Anglo-Australian multinational and the world's second-largest metals and mining corporation Rio Tinto is examining the technical implications of using hydrogen as a form of renewable energy in place of natural gas to reduce emissions from refining alumina.

The feasibility study amounting to A$1.2m, which is equally funded by the mining company and the Australian Renewable Energy Agency (ARENA) and will aim at replacing natural gas used during the calcination process. This is the last step in the production of alumina from bauxite and involves heating the mineral at around 1,000 degrees centigrade in heaters known as calciners.

Rio Tinto will use a lab-scale reactor at its Bundoora Technical Development Centre in Melbourne, Victoria, to simulate calcination heated by hydrogen. It will also conduct a preliminary engineering and design study conducted at its Yarwun alumina refinery in Gladstone, Queensland to understand the construction and operational requirements of a demonstration project at the site.

According to ARENA, Australia ranks as the world’s largest producer of bauxite and the largest exporter of alumina, which accounts for 15% of global alumina refining capacity. In 2019, alumina refining emitted more than 14mt of CO2 in Australia, accounting for around 24% of the country’s scope 1 manufacturing emissions.

Darren Miller, CEO of ARENA, said: “Exploring these new clean energy technologies and methods is a crucial step towards producing green aluminium. If successful, the technical and commercial lessons from Rio Tinto’s study could lead to the implementation of hydrogen calcination technology, not only in Australia but also internationally.”

Australia has delivered assurance to fund five hydrogen hubs to help decarbonize industry and prioritizing investment in hydrogen.