Abstract
Barium, manganese and aluminum are classified as critical and strategic metals due to their increasing importance in modern technological applications. This study investigates the formation and recovery of BaO and Al2O3 from a Ba-rich oxide manganese ore, from Zambia, through a combined hydrogen reduction, aluminothermic reduction- smelting, and alkaline leaching process. The manganese ore was first reduced using hydrogen, where all manganese oxides were fully converted to MnO at 800 °C. This was followed by aluminothermic reduction at 1500 °C, employing 25% excess aluminum, which resulted in the formation of a Mn–Fe alloy and a CaO-BaO-Al2O3 slag. The slag was subjected to an alkaline leaching using a Na₂CO₃–NaOH mixture (75:25). The leaching experiments were conducted at 90 °C with a solid-to-liquid ratio of 1:10. The slag was primarily composed of krotite (CaAlO4), with indicated approximately 70% leachability under the applied conditions. In this process, alumina was selectively dissolved into the leach solution, while calcium and barium remained predominantly in the leaching residue. Alumina and BaO were further extracted from the leaching and residue of solutions, respectively. Phase analysis, microstructural characterization, and chemical composition measurements were performed using XRD, SEM–EDS, and XRF. This integrated extraction approach enables the efficient recovery of manganese, alumina and barium from Zambian manganese ore.