Concentration study for low-grade refractory rhodochrosite by microwave calcination followed by magnetic separation

Owing to its own complex characteristics, large-scale resource utilization using the traditional calcination process makes it difficult to achieve efficient enrichment of rhodochrosite. In this study, the microwave calcination followed by magnetic separation was proposed as an effective method for enriching manganese ore from rhodochrosite. The phase transition and microstructural evolution of the main minerals during the calcination process were also systematically investigated. The experimental results demonstrate that magnetic fractions with a grade of 21.64%, recovery rate of 86.56% and yield of 71.20% can be obtained under the optimized conditions. The rhodochrosite phase is selectively changed to manganosite during the calcination process. The cracks between manganese minerals and gangue minerals inside the rhodochrosite, as well as the porous structure on the surface of the ore, are generated, which contributes to achieve more complete dissociation of manganese minerals in subsequent grinding, thereby facilitating separation and enrichment effects.