How does carbon monoxide reduce higher manganese oxides during smelting?

During the smelting of manganese ores, carbon monoxide acts as a reducing agent to facilitate the conversion of higher manganese oxides—specifically MnO₂, Mn₂O₃, and Mn₃O₄—into manganous oxide (MnO).1

While carbon monoxide is effective at reducing these higher oxides to the lower oxide state (MnO), it is important to note that the further reduction of MnO to metallic manganese cannot be achieved by carbon monoxide alone; this final step requires the use of carbon at elevated temperatures. The overall process is thermodynamically complex, as the presence of gangue oxides like silica can hinder the reduction by combining with MnO, necessitating the use of basic fluxes such as lime or magnesia to manage the slag composition.1