  Citation: Kudyba, A.; Safarian, J. Manganese and Aluminium Recovery from Ferromanganese Slag and Al White Dross by a High Temperature Smelting-Reduction Process. Materials 2022, 15, 405. https://doi.org/10.3390/ ma15020405 Academic Editors: Hansang Kwon and Vincenzo M. Sglavo Received: 3 November 2021 Accepted: 4 January 2022 Published: 6 January 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). materials Article Manganese and Aluminium Recovery from Ferromanganese Slag and Al White Dross by a High Temperature Smelting-Reduction Process Artur Kudyba 1,2, * and Jafar Safarian 1 1 Department of Materials Science and Engineering, Norwegian University of Science and Technology (NTNU), Alfred Getz Vei 2, 7034 Trondheim, Norway; jafar.safarian@ntnu.no 2 Centre of Materials Research, Lukasiewicz Research Network-Krakow Institute of Technology, Zakopia ´ nska 73 Str., 30-418 Kraków, Poland * Correspondence: artur.kudyba@kit.lukasiewicz.gov.pl; Tel.: +48-692-884-552 Abstract: The recovery of Mn and Al from two industrial waste of ferromanganese and aluminum pro- duction processes was investigated via implementing a high temperature smelting—aluminothermic reduction process. The experiments were carried out with or without CaO flux addition, and two dross qualities. It was observed that the prepared mixtures of the materials yield homogeneous metal and slag products in terms of chemical composition and the distribution of phases. However, the separation of produced metal phase from the slag at elevated temperatures occurs when a higher amount of CaO is added. Viscosity calculations and equilibrium study indicated that the better metal and slag separation is obtained when the produced slag has lower viscosity and lower liquidus. It was found that the process yields Al-Mn-Si alloys, and it is accompanied with complete recovery of Mn, Si and Fe and the unreacted Al in the process. Moreover, the quality of metal product was less dependent on the slightly different dross quality, and the concentration of minor Ca in metal is slightly increased with significant increase of CaO in the slag phase. Keywords: aluminothermic reduction; Al dross; FeMn; ferromanganese slag; white dross 1. Introduction Manganese is an essential element in the production of iron and exists in many steel grades and its primary application is for steelmaking. The second more important ap- plication is to produce aluminum alloys. Manganese is produced mostly in the form of ferromanganese (FeMn), silicomanganese (SiMn), and in pure form of electrolytic man- ganese. In 2019, 4.4 million tons of high carbon FeMn, 1.4 million tons of low carbon ferromanganese, 18 million tons of SiMn were produced [1]. The production of ferroman- ganese is accompanied with the generation of a high MnO-containing slag that is called high-carbon ferromanganese slag (HCFeMn slag) that has 20–45 wt% MnO. This slag can be fed into the SiMn production furnace as a part of the charge to supply the Mn of the SiMn product, and hence valorize the significant among of the Mn in HCFeMn slag [2]. However, In some cases the usage of HCFeMn Slag in SiMn process is not possible or economic and therefore this by-product is discarded/landfilled. Hence, the valorization of FeMn to recover Mn is important. Aluminum is the most abundant metallic element in the Earth’s crust, and it has many applications in different industries [3]. Primary aluminum is mainly produced from bauxite ore by the well-known Bayer process (alumina extraction) followed by the Hall–Héroult electrolysis for Al extraction from alumina. The secondary aluminum is produced through the recycling of Al scrap and wasted aluminum products [4–6]. In 2020, the global production of metallic aluminum was about 65.3 million metric tons [7]. In the production of primary aluminum, due to the exposure of liquid aluminum to oxidizing Materials 2022, 15, 405. https://doi.org/10.3390/ma15020405 https://www.mdpi.com/journal/materials