Our most significant impact on biodiversity is at our mine in Paragominas. A rehabilitation program is in place to monitor the local flora and fauna and rehabilitate the mined areas. We target a 1 to 1 rehabilitation of available mined areas (i.e. those mined areas not used by or reserved for long-term mining infrastructure).
To increase our knowledge and secure a science-based approach to rehabilitation, the Biodiversity Research Consortium Brazil-Norway (BRC) was established in 2013. The consortium is a partnership between research institutions from the State of Pará, the University of Oslo and Hydro. It performs research on biodiversity to improve rehabilitation, generating new data on fauna and flora for local researchers.
Our operations in Pará have state-of-the-art technology for the treatment and disposal of residues from the production of bauxite and alumina. Residue is generated through the aluminium production process and at all stages of the value chain. Our waste management approach focuses on the mitigation hierarchy: finding ways to avoid, minimize and recycle waste rather than sending it to landfill. Hydro’s mining and refining operations generate significant amounts of residue which are stored in large engineered storage facilities.
The mined bauxite must be washed before further processing, which generates tailings that are stored in dedicated tailings dams at our mining operation. In 2019, we initiated tests of the “Tailings Dry Backfill” methodology at the Paragominas mine, a novel approach to minimize the amount of tailings stored, by excavating dried tailings from the storage facility and returning it to the mined areas before they are rehabilitated. The methodology eliminates the need for continuous construction or upgrade of new permanent tailings dams. The pioneer application represents the end of the use of large dams for permanent storage of bauxite tailings. In 2020, we secured a license to start implementing the methodology full-scale within our operations.
Our tailings storage facilities at our bauxite mine Paragominas are monitored on a regular basis (using instrumentation) and are audited on an annual basis, including an international best practice audits by the external international geo-mechanical consultants Norwegian Geotechnical Institute and Geomecanica (2016 & 2019). Our bauxite tailings storage facilities at Paragominas differ significantly from those of iron ore mines, primarily due to the drier nature of our tailings and the more robust nature of the construction method in our tailings storage facilities.
Bauxite residue is a waste-product of the alumina refining process. This is filter pressed and stored in dedicated bauxite residue storage areas at our alumina refinery Alunorte. Alunorte uses an enhanced dry-stacking concept for handling bauxite residue. The use of modern press filters, built in connection with the new bauxite residue deposit DRS2, results in a bauxite residue with a very low moisture content (22 percent) which can be more efficiently stored. This new approach means that, per ton alumina produced, our bauxite residue now occupies only one fourth of the surface area in DRS2 than it did in our historical bauxite residue deposit (DRS1).
In addition to operating one of the largest water treatment systems in Brazil, Alunorte has invested R$675 million to increase storage capacity from four to six times the size of an Olympic pool per hour – aiming to keep operations well prepared to manage rainwater volumes also due to climate changes. This system is currently in place to ensure that all effluent is properly treated before discharging to the external environment, in accordance to local regulations.
In the world, only 3% of the 150 million tonnes of bauxite residue is recycled annually, which is still a very low rate. As part of our commitment to minimize operational impacts, we understand we need to push R&D activities further to re-use bauxite residue. As part of our efforts, earlier this year we started a local partnership with Senai Institute of Innovation in Mineral technologies (ISI-TM) to study the reuse of bauxite residues and the decrease of storage area. We will invest R$5 million in these studies up to 2022 and have set a target to utilize 10% of our bauxite residue output by 2030.
Managing our climate impact
We are working systematically to reduce our greenhouse gas emissions and our operations in Brazil are key to reach Hydro’s global target to reduce carbon emissions by 10% by 2025 and 30% by 2030.
One of our most important ambitions is to secure a greener energy mix at Alunorte, which is among the world’s largest and one of the most energy-efficient alumina refinery. In this respect, Alunorte is already an industry leader in Brazil at 0.7t CO2e per ton of aluminium oxide compared to the industry average of 1.2t CO2e.
Currently there are three active projects which will further reduce emissions to 0.5 t CO2e by 2025 and help us reach the 30% carbon emissions reduction target by 2030:
- Installation of a new electrical boiler in 2021 and two additional electric boilers in 2023
- Replacing all heavy fuel oil with natural gas by 2024
- Refinery energy efficiency
Updated: February 16, 2022