The Application of MnO2 in the Removal of Manganese from Acid Mine Water

In recent years, much attention has been devoted to developing inexpensive or alternative systems for treating acid mine drainage (AMD). Manganese is a common component of AMD, traditionally removed by precipitation; however, it is necessary to raise the pH above 10 to meet the standard discharge limit of <1 mg L−1, leading to high reagent consumption and inadequate final pH for discharge. This study investigates the removal of manganese from acid mine effluent and laboratory solutions using manganese dioxide (MnO2), an industrial residue. The acid effluent has a pH around 2.7 and a manganese concentration of approximately 140 mg L−1. Batch experiments assessed the pH influence and efficiency of MnO2 in Mn+2 removal. Results showed that in the presence of MnO2, can achieve discharge limits in the pH range of 6.8 to 7.2. Column experiments evaluated flow rate impacts, yielding best results for columns with mine water neutralized by limestone at pH 7.0 and a residence time of 3.3 hours. The maximum manganese loading capacity for MnO2 was approximately 14 mg g−1, with RAMAN spectroscopy revealing MnO2 was primarily composed of pyrolusite and hausmannite observed after contact with Mn+2 solution.