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.
Traditionally, manganese mining exploited rich deposits and produced rich granular concentrates with high commercial acceptance. But the scarcity of these rich ores results in searches for new alternatives to support the market demand. This work, for example, proposed the evaluation of a low-grade manganese ore concentration, aiming to produce a concentrate to be destined steelmaking. The liberation study, realized in the characterization step, showed the associations between grouped manganese oxides/hydroxides, spessartine, and quartz (minerals with predominantly proportions in gondite). The material studied was a gondite (metasedimentary rock with low manganese content), submitted to characterization and pre-concentration. Flotation results pointed to a metallurgical reasonable recovery of 88.76%, but a product with manganese content equal to 21.51%, indicating a low enrichment of 1.11. The greatest metallic recovery was 92.48% to a size range of –147 +38 μm applying the magnetic concentration tests with field strengths of 15,500 Gauss. The magnetic concentration product with the best metallic recovery (92.48%) produced manganese content equal to 22.84%, representing an enrichment of 1.18. The BSE images revealed particles of manganese oxides with the liberated surface, but also the permanence of spessartine particles involved by the other manganese oxides.
Resumo Medidas de adsorção, tensão superficial e potencial zeta (PZ) são as ferramentas mais usadas para entender os fenômenos interfaciais e, consequentemente, os aspectos químicos envolvidos nos processos de flotação. No presente trabalho avaliou-se a adsorção dos coletores oleato de sódio (OLS) e dodecilamina (DDA) em hematita e quartzo, respectivamente, a partir da medida indireta da adsorção dos reagentes baseada em determinações das tensões superficiais das soluções residuais dos coletores após adsorção. Mediu-se também o potencial zeta dos minerais estudados em função da concentração dos coletores. As medidas indicaram que ocorreu a adsorção. Em relação à hematita os resultados sugerem a ocorrência de adsorção química. Para os ensaios realizados variando-se o tempo de adsorção, observou-se o aumento na adsorção de OLS sobre a hematita em função do tempo. Para o sistema quartzo-dodecilamina os resultados não apresentaram tendência quanto à influência do tempo na adsorção. Esse comportamento sugere que a cinética de adsorção de dodecilamina sobre o quartzo é mais rápida, ocorrendo adsorção nos primeiros instantes de contato entre a solução e o mineral.
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.
Estudo da ação de reagentes na dispersão de minério oxidado de zinco por eletroforeseStudy of reagent action in the dispersion of zinc oxided ore by electrophoresis
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