Recovery of Copper, Iron, and Alumina from Metallurgical Waste by Use of Hydrogen

Sankey diagram for the valorisation of copper slag

Abstract: Substituting carbon with hydrogen is one of the few ways metal production can potentially become free of CO2 emissions. Moreover, the metallurgical industry produces significant amounts of waste. The present work presents a circular concept that will be pursued in the HARARE project, based on increasing waste recovery by the use of hydrogen. The project will tackle two example cases: bauxite residue and copper smelter slags. The common theme is to use hydrogen to selectively reduce iron and copper, making it possible to extract these metals. Through a series of pyro and hydrometallurgical steps, as well as mechanical separation, it is also possible to recover secondary valuables like alumina, molybdenum, cobalt, nickel, zinc, and scandium. The final remaining residues can be valorised as building materials for a truly zero-waste concept. In this paper, the different process streams for the two example cases are laid out, including the valorisation of secondary material streams.

Read the full paper, published at TMS 2022, by Casper van der Eijk and Halvor Dalaker: