Influence of Mn2+ ions on depression of quartz and spessartine in gondite ore.

Abstract

Low-grade manganese ores that are composed of manganese oxides, wad, quartz, iron oxides, gibbsite, and especially of spessartine (Mn3 Al2 (SiO4 ) 3 ) are known as gondite. Spessartine is a mineral with a high content of silica (SiO2 ) and alumina (Al2 O3 ) 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 Mn2+ 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 Mn2+ (1000 mg/L) was added previously to the depressant. Zeta potential determinations showed that Mn2+ 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.