Mintek, South Africa’s national mineral and metallurgical research institution, is actively involved in developing and demonstrating sustainable pyrometallurgical processes and technologies. The need to increase the sustainability of pyrometallurgical processes and technologies significantly increases the urgency to develop and demonstrate flowsheets with improved energy efficiency and effluent emissions, including demonstrating flowsheets that can incorporate alternative carbon-free reductants. Mintek’s Pyrometallurgy Division recently completed demonstration of a carbon-free process for the production of ferromanganese (FeMn) alloys from manganese (Mn) ores and Mn-containing waste by using hydrogen and aluminium metal as reductants (i.e. HAlMan process).
The HAlMan process focuses on treating primary and secondary raw materials in a sustainable manner while pursuing the decarbonization of industrial processes. Mintek pilot test work demonstrated smelting-aluminothermic reduction of pre-reduced lumpy Mn ore (primary raw material) and high carbon ferromanganese slag (secondary raw material). The pilot campaign was carried out in July 2024 over period of a week whereby over 3600 kg of Mn-containing material was smelted. The smelting tests were conducted in a 200 kW DC arc furnace facility featuring a 1 m shell diameter furnace with a single central electrode (see image). The test work successfully demonstrated carbon-free production of ferromanganese alloy with more than 70% Mn. The by-product slag generated had alumina (Al2O3) concentrations up to 54% Al2O3, providing for an alumina-rich feedstock for downstream refining processes, thus generating zero waste. Environmental measurements indicated insignificant CO2 emissions, demonstrating the significant potential impact of the HAlMan process in mitigating CO2 emissions in production of Mn alloys.
