Investigation of Copper as Collector Metal in Sodium-Oxide Fluxed Aluminothermic Reduction of Manganese Ore

Aluminothermic reduction is gaining renewed interest as an alternative processing route for the circular economy. A unique Na2O-fluxed MnO2 ore formulation with a small quantity of carbon reductant was applied to ensure rapid pre-reduction to MnO. This approach negates the pre-roasting step. The Na2O flux enables the formation of the water-soluble compound, NaAlO2, which enables recycling of Al2O3 for aluminium production. The addition of copper as a collector metal improved the overall alloy yield from 43% to 57%, which includes a 6% increase in Mn recovery to the alloy. The product alloy is a medium-carbon Fe–Mn–Si–Al–Cu complex ferroalloy that can be used as a steelmaking ferroalloy additive. The ferroalloy consists of 54% Mn, 19% Fe, 2.1% Si, 2.6% Al, 21% Cu, and 1.2% C. This carbon content is modulated by low-carbon solubility copper, despite the use of a graphite crucible. The formulated slag exhibits high Al2O3 solubility, enabling effective alloy–slag separation from the high Al2O3 content slag of 52% Al2O3. Gas–slag–metal equilibrium calculations for 1650 °C–1950 °C overlap with the experimentally produced alloy chemistry in %C and %Si, but not the %Al, as the uptake of aluminium exceeds the equilibrium calculation at 0.03–0.17%.