Characterisation of manganese ores and slags for production of ferromanganese and Al-Mn master alloys

Abstract

Manganese (Mn) ores fluctuate considerably in chemistry and other properties. It is well known that the properties of Mn ore have a large influence on the technology and yield of Mn alloy production. This work aims to characterize Mn ore and slag properties for the production of ferromanganese (FeMn) through a prereduction with hydrogen (H2) and subsequent aluminothermic reduction. The raw materials for this process can be aluminium (Al) containing dross or scrap and Mn ores. Interesting by-products of the process can be Al-Mn master alloys and a slag enriched in rare earth elements (REE) from the Mn ore. Chemical composition, especially critical raw materials (CRM) including REE, porosity, and melting and softening have been characterized with various methods. The implications of the outcomes on the extraction of critical raw materials are also discussed. It is concluded that the CRM, particularly REE tends to accumulate in the slag. Current slags are approximately 9 times less porous than Mn ores. Mn ores in the current work soften at 970-1800°C, and melt at 1460- 1850°C. All current ores expand maximum 16% and reduce to -70% of the original volume.