Efficient enrichment of low-grade refractory rhodochrosite by preconcentration-neutral suspension roasting-magnetic separation process

Low-grade refractory rhodochrosite ores are difficult to be utilized by traditional beneficiation process owing to their complex characteristics. In this study, preconcentration-neutral suspension roasting-magnetic separation process was firstly proposed, and the thermodynamics, kinetics, phase and microstructure evolution of mineral reaction during rhodochrosite roasting were systematically studied. The results show the raw ore was preconcentrated by high intensity magnetic separation. The suspension roasting was carried out under optimum conditions. After magnetic separation, the magnetic separation concentrate with 24.30% manganese grade and 59.61% manganese recovery was obtained. Manganese ore was transformed from MnCO 3 to MnO during roasting. The thermal decomposition reaction of manganese ore conformed to random nucleation and subsequent growth model. The original minerals was destroyed due to the cracks caused by the decomposition of carbonate in rhodochrosite ore, which was conducive to the full dissociation of useful minerals and gangue mineral, and further improve the separation and enrichment effect. • Preconcentration-neutral suspension roasting-magnetic separation were proposed. • This process performs stable production, with high-quality roasted product. • Manganese ore was transformed from MnCO 3 to MnO. • Thermal decomposition reaction conformed to random nucleation and growth model.