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.
The goal of the ENSUREAL project is to ensure zero waste production of alumina in Europe. This has been done by developing a zero-waste process for alumina production that can handle a wider range of bauxite than the existing process. This was 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.
The main conclusions from the project are:
Alumina can be produced with the ENSUREAL process. The produced iron is suited for applications where a high wear resistance is of importance. The grey mud by-product can be used in the building sector as a cement replacement.
However, the quality of the produced alumina needs to be improved before it meets the requirements of the industry. Such as, the particle size needs be increased and the silica content decreased. The capital investment for a full-scale ENSUREL factory is high and it is difficult to argue for a ENSUREAL refinery compared with a Bayer refinery from a business case point of view. The best case from a business and environmental point of view is when the ENSUREAL process is used for the processing of bauxite residue. In this case the "Red mud" problem can be solved with a method that can give a positive operational income.
