Selective Recovery of Manganese from Low-Grade Ferruginous Manganese Ores Through SO₂ Leaching

Current study investigates the SO₂ leaching of low-grade ferruginous manganese ores to selectively recover manganese as MnSO₄ and subsequently produce battery grade electrolytic manganese dioxide (EMD) from the purified MnSO₄. The effect of leaching process parameters such as leaching duration, temperature, and the SO₂ flow rate on the Mn recovery was studied in detail. Leaching duration and SO₂ flow rate had a significant effect on the Mn recovery. Under optimum process conditions, specific SO₂ requirement (SSR), i.e., SO₂ flow rate per gram Mn in the leach slurry was calculated to be 0.014 LPM (liter per minute), which resulted in 97.9% Mn recovery using grade 1 ore (Mn total = 17.16). Effect of ore grade on the SSR was studied using grade 2 ore (Mn total = 26.29). Using the SO₂ flow rate calculated from the SSR value, a Mn recovery of 94% was realized for grade-2 ore. MnSO₄ generated through the leaching was used in electrowinning to produce EMD with a purity of 88.01% and battery active γ structure. Graphical abstract: [Figure not available: see fulltext.]