Reductive roasting of iron-rich manganese oxide ore with elemental sulfur for selective manganese extraction

Abstract

It is very important to selectively reduce manganese oxide over iron oxide for extraction of Mn from iron-rich manganese ore. In this study, reductive roasting of an iron-rich manganese oxide ore with elemental sulfur as reductant was investigated. The experimental results demonstrated that manganese dioxide can be selectively reduced with elemental sulfur and extracted via acid leaching, which was largely depended on the sulfur addition. Lower sulfur addition (S/Mn molar ratio<1.0) results in higher selectivity, which is independent of roasting temperature. More than 95% manganese and less than 10% iron were extracted through acid leaching under the roasting conditions of 400-600 o C with S/Mn molar ratio of 0.6. The contents of manganese sulfide and sulfate in the roasted product increased with increasing sulfur addition, while they decreased distinctly at temperatures above 550 o C. The thermodynamic analysis also proved that manganese dioxide is more easily reduced than iron oxide by sulfur at 300-900 K. The phase transformations during reductive roasting revealed that sulfides (MnS and FeS 2 ) were favored at temperatures lower than 550 o C whereas the oxides (MnFe 2 O 4 and Fe 3 O 4 ) were predominant at higher temperatures. The reduction of iron oxide mainly occurred at large sulfur additions (S/Mn>2.0) and the roasting temperature exerted a significant impact on the phase composition of roasted product.

Formation mechanism of Fe-Mo master alloy by aluminothermic reduction of MoS2-Fe2O3 in the presence of lime

“…As it is shown, the produced slag contains the main CaS, Al 2 O 3 and CaMoO 4 phases, and also the calcium-dialuminate phase (CaAl 4 O 7 ) at low value. The conditions for the formation of iron-sulfur compounds, especially iron sulfides, are also reasonable [35]. The presence of the CaS phase among the slag components demonstrates the probability that the CaSO 4 phase produced in the previous stages at lower temperatures of heating process, would be completely decomposed due to high temperature of combustion synthesis reaction and this argument could be viewed as a reason for weight loss in TGA curve of the FeMo Mix sample during and after the combustion synthesis, as shown in Fig.…”

Novel Understanding of Simultaneous Extraction of Vanadium and Manganese from Vanadium Slag and Low-Grade Pyrolusite Based on Selective Oxidation–Reduction Roasting

“…Most LGP in China is of low Mn grade and high Fe content (Mn/Fe mass ratio < 3). , During manganese extraction from LGP, reductants need to be added to the roasting or leaching systems to reduce Mn 4+ to Mn 2+ , while some iron is also reduced and eventually transferred to the manganese-containing liquid. − This makes the separation of vanadium and manganese from LGP difficult in the application of LGP. Much more reductants have been applied and reported in the previous works; − however, complete separation of iron and manganese has not yet been achieved.…”