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Integrated cross-sectorial approach for environmentally sustainable and resource-efficient alumina production

Periodic Reporting for period 2 - ENSUREAL (Integrated cross-sectorial approach for environmentally sustainable and resource-efficient alumina production)

Período documentado: 2019-04-01 hasta 2020-09-30

The goal of ENSUREAL is to ensure zero waste production of alumina in Europe. This will be done by developing a zero-waste process for alumina production that can handle a wider range of bauxite than the existing process. This new process will minimize the environmental impact of bauxite mining and alumina production.

Global aluminium metal consumption is expected to grow during the coming years. Aluminium metal is produced through electrolysis from aluminium-oxide, also called alumina. Alumina is produced by the Bayer process from bauxite. The Bayer process has as main drawback that it does not utilize all elements in the bauxite ore and thus produces a lot of waste. This waste is called bauxite residue, or red mud because of its red colour. For every kilo of aluminium metal more than 1 kg of red mud is produced. This waste is usually land-filled in large ponds. The problem with red mud will increase during the coming decades as bauxite qualities gradually contain less aluminium and more of the mined material will end up as waste. The ENSUREAL project addresses the production of alumina, through the introduction of a new technology (improved Pedersen process) that enhances the process' yield and its energy and environmental performance. The increased costs of processing should be balanced with an increase in revenue from the different products, cheaper bauxite resources and no costs for land-filling.

This is being carried out, along with the development of: key valorisation routes, realistic business scenarios based on life cycle and cost analyses and innovation, dissemination and communication strategies.
During the second reporting period, the focus has been on optimising the pyrometallurgical (WP2) and hydrometallurgical (WP3) processes parts, to ensure the process parameters for the pilot plant (wp4) can be established.

WP1 has finalized its work on identifying exploitable raw materials sources and giving recommendations to reduce EU imports’ dependence. The project group is in contact with several bauxite suppliers that want to have their raw materials tested in the ENSUREAL process.

In the scope of WP2, more work was done to refine the recipe for successful slag production and prereduction with hydrogen. Several different raw materials were tested.

WP3 has been focused on maximising the alumina recovering from the slags obtained in WP2 (ensuring a grey mud product that can be characterised by Luvena in WP5 in the next reporting period) and maximising the alumina hydrates’ precipitation from pregnant alkaline solutions. The hydro metallurgical step is the most critical to reach a process that is economically viable. It is a balance between maximizing the aluminium yield of the process and minimizing the energy consumption (amount of water needed and temperature difference between leaching and precipitation).

As part of WP4, the pilot plant has produced it's first slag that will be leached during period 3.

The effort to study the by-products has started in WP5 where the investigation of iron and grey med is ongoing.

Based on feedback retrieved from WP1-WP5, the sustainability of the Pedersen method has been developed around two regions: Greece and Norway. Furthermore, the LCCA will compare the economic performance of the ENSUREAL project to the state of the art. The selection of most promising regions for the method has allowed to start an analysis of the business environment for ENSUREAL. The partners have agreed to explore two different scenarios, using different raw materials’ compositions (including bauxite/pre-reduced bauxite and bauxite residue). Innovation, dissemination and communication strategies have also been put into place. This comprises the use of an innovation radar tool, on-line meetings with stake holders and publication of relevant articles.
At each step of the process, ENSUREAL’s innovations are going in line with what was expected at the beginning of the project
- For the Iron production (Pyrometallurgical step): biochar has been successfully used for lab and pilot experiments and pre-reduction with hydrogen experiments have been conducted successfully.
- For the alumina production (Hydrometallurgical processing): the next reporting period will contain results in alumina precipitation and calcination;
- For the Grey Mud residue: initial characterization of pig iron and grey mud has been performed for two of the sectors considered (fertilizers and cast-iron production).

Once the mass and energy balanced are fixed, the expected impacts vs Bayer process in terms of energy savings (1.8 GJ/t alumina) and CO2 emissions will be provided by the LCA, which is being carried out by AdMiRIS in WP6.
Pre-reduction test
Bayerite produced during the project
Small scale pyrometallurgical tests
First progress meeting in Trondheim
Pyrometallurgical work
Precipitation experiments in the lab.
ENSUREAL consortium
Hydrometallurgical work