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Sustainable Refining: Alcoa Brings Innovative Bauxite Residue Filtration Technology to Brazil


The aluminum industry’s lowest-carbon alumina refining system is about to get even greener, thanks to a new project at the Poços de Caldas refinery in Brazil.

A new bauxite residue filtration facility will transform how the refinery manages bauxite residue – a byproduct of the alumina refining process that is primarily made up of red mud and coarse sand. The Poços de Caldas refinery will use a process known as press filtration, which will reduce water usage and require less land to store residue.

Watch a video about how the process is currently working in Western Australia

Alcoa first adapted the filtration technology at the Pinjarra and Kwinana refineries in Western Australia, where the process reduces annual freshwater use. Those two refineries have the capability to reduce their freshwater use by a collective 2.2 gigaliters (581 million gallons) through the process. This is equivalent to the amount of water needed to fill 880 Olympic-sized swimming pools.

With the technology, bauxite residue is forced through very large filters that squeeze out the water before it is stored, reducing the amount of land required to store the material and allowing for the water to be recycled in a closed-loop system.

“Re-defining what it means to be the most sustainable upstream aluminum company requires a deep commitment to continuously improving our footprint and a relentless pursuit of innovation that will help us progress,” said John Slaven, Alcoa Executive Vice President and Chief Operations Officer. “By continuing to roll out this bauxite residue filtration technology across more of our refineries, we continue to set new benchmarks in regard to resource management while making progress on goals aligned with our Advance Sustainably strategic priority.”

Construction of the bauxite residue filtration facility at Poços de Caldas will begin in August 2021. The project is estimated at approximately $60 million (USD), with approximately half to be spent in 2021 and anticipated in the Company’s consolidated capital expenditure outlook in 2021. Construction is expected to be complete in the second quarter of 2022 with commissioning by the end of that year.

The project is also expected to deliver significant economic benefits to the local community, including the creation of around 20 direct jobs and approximately 500 indirect jobs supporting facility construction.

Alcoa’s ambitious vision for bauxite residue
This project is an outcome of Alcoa’s strategy to sustainably manage bauxite residue and innovate new uses for the material.

Through our expanded use of bauxite residue filtration technology, Alcoa continues to progress toward its goal of reducing global bauxite residue land requirements per metric ton of alumina produced by 15% by 2030, from a 2015 baseline. The company has already delivered a 12.8% reduction and this project in Brazil will help further improve that performance.

Alcoa also continues to build partnerships focused on developing innovative pathways for bauxite residue re-use, turning the waste product into a resource. Examples include using the residue as a material for low-carbon cement as well as transforming it into a soil-like substance. More details of those industry-leading initiatives can be found here.

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