A Process for Extraction of Manganese from Manganese Oxide Ores by a Novel and Efficient Roasting-Acid Leaching Technique

In this article, a novel efficient and environmental reductive roasting-acid leaching technique was proposed by a combined pretreatment of the microwave heating and reduction of alkali lignin. Factors influencing the leaching of manganese from manganese oxide ores were investigated, such as heating modes (microwave heating and conventional heating), microwave roasting parameters and acid leaching parameters. The results indicated that the leaching ratio of manganese by microwave heating was significantly higher than that by conventional heating under the same conditions. The reduction of manganese oxide ores by microwave heating was completed at a roasting temperature of 150°C and a roasting time of 5 min with the addition of 50% alkali lignin with the reduction sequence of MnO 2 → Mn 2 O 3 → Mn 3 O 4 → MnO. A 97.43% leaching ratio of manganese was obtained from the roasted ore, which was leached by a 1.5 mol/L concentration of sulfuric acid at a 50°C leaching temperature, 50 rpm stirring speed and a 10:1 liquid-to-solid ratio for 5 min. Compared to the conventional reductive roasting-acid methods, the proposed technique was performed at a considerably lower temperature and shorter time, with higher reducing agent utilization ratio to processing the different manganese oxide ores.