Conference Agenda

Recent advancements in the production of low-carbon iron from bauxite residue have indeed yielded promising results, paving the way for sustainable iron production processes. Bench-scale and pilot-scale studies have underscored the technical and economic viability of this approach to start the microwave plant engineering for a 50 000 tpy bauxite residue capacity. Specifically, the utilization of carbon-capturing sources during growth, such as charcoal and biomass, coupled with microwave energy, has been instrumental in the reduction of iron. Moreover, the use of renewable energy sources to power microwave energy further enhances the sustainability profile of the process. The resulting iron briquette exhibits exceptional metallization, surpassing 90%, with iron content ranging from 92% to 95%, and notably low sulfur and phosphorus levels. These characteristics not only meet but exceed the stringent specifications required for steel production. The reuse of bauxite residue not only minimizes waste but also creates a sustainable and economically feasible product, thus closing the lifecycle loop of alumina production. This innovative approach not only addresses environmental concerns associated with traditional iron production methods and bauxite residue handling but also offers a feasible pathway towards achieving carbon-neutral steel production. Furthermore, the material that remains after the conversion and production of pig iron, having undergone thermal conversion, exhibits interesting characteristics and is under development for use mainly in civil construction, ceramic and steelmaking sector, and other applications with high demand, potentially enabling the utilization of 100% of the bauxite residue.

Several process alternatives are being investigated for the use of bauxite residue (BR) as a secondary metallurgical resource. These processes aim primarily at the extraction of the major metal values found in BR, i.e., Fe, Al and Na, and attempt to integrate novel metallurgical technologies to reduce the CO2 footprint. One of these technologies is the reduction of BR with H2 for the production of Fe, taking place in a temperature range below the melting point of Fe. In this process, the remaining unreduced oxides contain the Al content of BR in aluminate phases which need to be leached efficiently. In this paper, hydrogen reduced pellets of BR/CaO mixtures are being hydrometallurgically treated to leach the alumina content. The pellets are first chemically and physically characterized. The main challenges identified are (i) the entrapment of Fe in the oxide matrix and (ii) the formation of unleachable aluminate phases. Two approaches were tested in an attempt to assess the optimum way of separating the Fe content of the pellets and the efficient leaching of the aluminate phases: (a) an alkaline leaching stage first/Fe separation second approach, in which standard leaching tests are first performed with a Na2CO3 solution to separate the Fe from the leaching residue and (b) a Fe separation first/alkaline leaching second approach, where the pellets were smelted to separate pyrometallurgically the Fe content from the aluminate phases and then leaching was performed with a Na2CO3 solution. Results indicate that the second process route is more efficient for the separation of Fe.

The refining of alumina produces significant amount of residue (BR) which is similarly produced by other ferrous and non-ferrous metals industrial sectors. Alumina refining, iron and steel production can establish innovative industrial symbiosis models for the construction sector to valorise large volumes of residues and by-products. In the present study, results from a European pilot plant to produce and evaluate the performance of a new road sub-base concept using bauxite residue, coal fly ash and ground granulated blast furnace slag. The paper includes details and results of the project, the experimental work undertaken to determine the mechanical and environmental performance and the results achieved from the quality control and monitoring plan established. Mechanical results were compared with the Spanish and Irish regulations for hydraulically bound materials for roads. The results show that the key performance parameters have been achieved and that the new material developed is suitable for road sub-base construction. The proposed solution appears robust from a safety and environment point of view and the project showed no major construction process difficulties. In summary, the field evaluation has demonstrated the added value of using waste and by-products as alternative construction materials delivering a mechanical performance like soil cement pavement layer and a suitable circular economy strategy to reduce the environmental impact of alumina production and BR management.

In 2015, European Aluminum established its Innovation Hub as a collaborative platform to accelerate the transformation to a clean and circular Europe for aluminum producers and cross-sector partners. Since then, the Innovation Hub of European Aluminum plays a crucial role in facilitating the development of European Union (EU) funded collaborative projects across the aluminum value chain by bringing together the necessary participants from the membership, the broader industry, and Research, Development & Innovation organizations. Focusing on the upstream part of the aluminum value chain, one of the most significant challenges is related to the bauxite residue (BR) generation as well as its environmentally and socially acceptable valorization pathways to reduce reliance on landfilling. European alumina refineries are actively seeking innovative solutions to transform this challenge into an opportunity by developing environmentally safe and economically viable solutions which could possibly result in market-accepted BR-based products. Within this context, H2020 projects RemovAL (Grant Agreement no. 776469-completed in April 2023) and ReActiv (Grant Agreement no. 958208-in progress) aim to promote the combination of multiple technologies and establish industrial symbiotic schemes, especially with the construction sector. These cross-sectoral projects seek to overcome environmental issues and technological barriers in a financially efficient manner, ultimately facilitating meaningful BR valorization. As part of both consortia, the Innovation Hub facilitates the cross-sectoral collaboration and advocates for the need to adapt the current EU legislation for enabling the proper valorization of bauxite residue under the overall concept of circular economy