Clean technology of manganese extraction from low grade refractory manganese ore by suspension calcination based on mineral phase transformation

Abstract

Conventional methods for roasting manganese ore frequently exhibit complex characteristics that lead to suboptimal resource utilization, failing to satisfy industrial standards for efficient manganese enrichment. This research presents an innovative technique aimed at improving manganese extraction from rhodochrosite, utilizing a combination of suspension calcination and strong magnetic separation. We thoroughly examine the phase transformations and microstructural alterations of the primary minerals during the calcination process. Our results reveal that, at a calcination temperature of 650 °C, with a duration of 25 minutes, a feed quantity of 50 g, a gas flow rate of 500 mL min⁻¹, and a magnetic field strength of 6500 Gs (equivalent to 650 mT), a magnetic product can be achieved with a yield of 61.83%, a manganese grade of 21.16%, and a recovery rate of 85.06%. By modifying the calcination conditions, the manganese phase transitions from rhodochrosite to manganosite. Furthermore, the thermal breakdown of carbonates in the ore induces surface fissures in the minerals, weakening the structural integrity of the original minerals, which aids in the effective separation of valuable minerals from the gangue, thereby enhancing the overall enrichment process.