Preparation of chemical manganese dioxide from Moroccan pyrolusite mine waste

The preparation of manganese(IV) oxide from a Moroccan pyrolusite mine waste was studied. A sample of mine waste containing about 35% Mn was leached with 6.36 M HCl at 70 °C for 1 h with 98% leaching efficiency. The resulting solution was conditioned at pH 5 and sodium hypochlorite was added to obtain various oxide phases (Mn2O3, MnO2). Finally the oxides were transmuted by addition of nitric acid to obtain the α-MnO2, nH2O phase with 97% purity.