Mud2Metal: Lessons Learned on the Path for Complete Utilization of Bauxite Residue Through Industrial Symbiosis

A new concept for a holistic exploitation of the bauxite residue (BR) is presented, where a multitude of niche and bulk application products are produced, leading to a near zero-waste, financially viable, and environmentally benign process. Based on the combination of recent research results, the "Mud2Metal" conceptual flow sheet was developed in order to produce added value products rationalizing BR sustainable valorization. The Mud2Metal flow sheet is analyzed technologically, environmentally, and economically, addressing the challenges and the effects of each processing step, for the case of the Greek BR. The Mud2Metal flow sheet is focused on the selective removal of rare earth elements, the subsequent production of pig iron for the iron and steel industry, and the valorization of the residual slag's engineered mineral matrix into a variety of building materials. Based on further technological innovation and flow sheet integration/optimization, the plant operation could become economically profitable for the alumina industry, environmentally benign, and socially acceptable; in one word: sustainable.