Efficient and Complete Exploitation of the Bauxite Residue ( Red Mud ) Produced in the Bayer Process

The Bayer Process for the production of alumina from Bauxite ore is characterized by low exergy efficiency and it results in the production of significant amounts of dust-like, high alkalinity bauxite residues known as red mud. Currently red mud is produced almost at 1 to 1 mass ratio to metallurgical alumina and is disposed into sealed or unsealed artificial impoundments (landfills), leading to important environmental issues. A patent-pending energy and exergy efficient process has been recently developed by the Advanced Mineral Recovery Technologies (AMRT, Ltd.) and NTUA’s Laboratory of Metallurgy, for the direct transformation of red mud into valuable products, such as pig iron and mineral wool. The novel process utilizes an innovative electric arc furnace (EAF) technology to achieve the carbothermic reduction of the red mud waste without any pretreatment, producing pig iron and viscous slag suitable for direct mineral wool production. Thus, the environmental footprint of the Bayer Process is reduced substantially, as the initial bauxite ore is exploited in full and no solid wastes are produced. The overall exergy efficiency of the new bauxite exploitation schema increases from 3 % in the conventional Bayer Process to 6 to 9 % depending on the method used to produce the electricity needed to power the Electric Arc Furnace. Additionally, as the novel process enables the single step co-production of two highly valuable by-products (pig iron and mineral wool), it has the potential to significantly increase the versatility and profit margin of the alumina producing industry. In this paper a thermodynamic study and preliminary experimental results of the red mud treatment process are presented, along with an overall energy, exergy and economic analysis of the new bauxite exploitation schema. Balomenos, Gianopoulou, Panias, Paspaliaris, Perry, Boufounos Proceedings of EMC 2011 746