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Low-grade manganese ores that are composed of manganese oxides, wad, quartz, iron oxides, gibbsite, and especially of spessartine (Mn 3 Al 2 (SiO 4) 3) are known as gondite. Spessartine is a mineral with a high content of silica (SiO 2) and alumina (Al 2 O 3) that causes a decrease of the enrichment in manganese oxide concentrates by flotation, giving this ore more complexity for processing. Thus, by ensuring a higher selectivity between manganese oxides minerals and silicates, the use of gondite reserves becomes viable, and the correct reagent type can be useful for this objective. Moreover, there are few publications devoted to the study of spessartine in flotation. So, this study investigated the effects of Mn 2+ ions on quartz and spessartine depression and showed positive results with the reduction of quartz floatability from 7.06% to 1.23% and the spessartine from 27.30% to 17.12% respectively when the Mn 2+ (1000 mg/L) was added previously to the depressant. Zeta potential determinations showed that Mn 2+ can act as a silicate activator, possibly by facilitating the SiO(OH) 3 adsorption. Infrared spectroscopy analysis revealed absorption bands at 3,450 cm-1 and 3,400 cm-1 frequency for quartz and spessartine and the adsorption of Mn(OH) 2 was responsible for this result.

The depletion of hematitic mineral deposits and the growing content of itabirites in the iron ores mined in the Quadrilátero Ferrífero-Brazil calls for further studies in an effort to adjust the actual technologies, due to the different behaviors of the different mineral species present in the new ore. Currently, little is known about the fundamentals of particle separation in Humphreys spiral, as far as the different particles morphologies. Therefore, the performance of a spiral concentrator was evaluated by a sequence of friable itabirite tests at an industrial scale. The smallest iron content and smaller metallurgical recovery attained in the tests owe to a small particle size in sample (33.67% < 106 µm and d80 ≈ 675 µm) and a greater content of tabular hematite. The sample showing the worst metallurgical recovery results (46.20%) and iron content (62.39%) also presented the highest percentage of tabular hematite (68.69%). The samples with a greater amount of martite produced sinter feed with the highest metallurgical recovery (65.65%). It is believed that there was a predominant effect of the hematite morphology on other parameters such as density. Thus, a careful characterization step and the adoption of blending procedures concerning iron content and morphology simultaneously can be positive for the process.

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