Efficiency of Mn passive treatment from mine drainage (MD) is limited, in the presence of Fe, because of the wide stability field of dissolved Mn(II) species. Physicochemical and mineralogical characterization, as well as static leaching tests at pH 7 (CTEU-9) of four samples were performed to assess Mn immobilization processes from MD and post-treatment stability of residues. Samples consisted of half-calcined dolomite, from three column reactors that treated Mn in MD. The first residue originated from real acid mine drainage treatment (R-AMD; pH 2.4; 623 mg/L Fe; 22 mg/L Mn), the second from real contaminated neutral drainage (R-CND; pH 6.7; 0.6 mg/L Mn) and the third from synthetic CND (S-CND; pH 6.8; 47 mg/L Mn). A sample of calcite (CAL) was also collected in a field oxic limestone drain that treats AMD (pH 4.1; 10.2 mg/L Fe; 12.4 mg/L Mn) on a closed mine site. Mineralogical analyses showed Mn immobilization in the form of MnOx. In R-AMD residues, Fe and Al concentrations almost doubled relative to half calcined dolomite before MD treatment, while Mn removal was inefficient. In S-CND residues, high concentrations of Mn were immobilized (>6.6 g/kg). The mineralogy of R-AMD residues showed that Fe precipitates coated the dolomite, in the form of Fe-(oxy)hydroxysulfates. Half-calcined dolomite is effective for Mn removal in S-CND, but Fe inhibits Mn treatment in AMD. Metal(loid)s in eluates were below the threshold limits, but the pH of R-CND (11.1) and S-CND (10.5) residues no longer met the discharge criteria (pH 6.0 to 9.5).