Introduction
Manganese is widely used in industrial applications, such as manganese-steel, catalyst and battery. Naturally, manganese ore can be found as pyrolusite (MnO2), psilomelane (BaMn9O16(OH)4), manganite (Mn2O3.H2O), haussmannite (Mn3O4), Rhodochrosite (MnCO3), Rhodonite (MnSiO3) etc. Manganese ore are also found together with others minerals such as quartz, kaolinite, dolomite, cordierite, hematite and lithiophorite. Determination of these phases is very important for smelter operations. Accurate knowledge of the phase composition of the ore is imperative in establishing empirical relationships between the quantitative mineralogical data and the amounts of energy and reductant needed during the smelting process as the manganese containing minerals differ in melting points and have variable oxidation states, hence will behave differently during smelting. Therefore, in this present study we determined the phase compositions of four manganese ore samples and compared the manganese concentration with that obtained by wet classical analysis.
Results and Discussion
Four manganese ore samples namely SARM 16, SARM 17 and two commercial samples were taken and their mineralogical compositions were quantified using powder XRD. XRD analysis has few advantages over SEM-EDS analysis for smelter operations namely,
- the preparation of the XRD samples is simple and cost effective
- mineral identification by XRD is considered more robust than by EDS (XRD patterns for minerals like hausmannite and bixbyite are clearly different while the EDS signatures are more or less identical),
- fine-grained texture of particles may hinder the determination of hematite and other minerals by EDS, which is not the case with XRD,
- the acceptable limit for the major phases (1 – 2 wt %) is sufficient for evaluating the smelting behaviour of the ore.
SARM 16
| Minerological phases of Manganese identified | Manganese (wt %) | Manganese (wt %) obtained classically |
| Braunite and manganite | 48.60 | 49.17 |
SARM 17
| Minerological phases of Manganese identified | Manganese (wt %) | Manganese (wt %) obtained classically |
| Haussmanite, bixbyite, rhodochrosite, pyrolusite, rhodonite and manganite | 38.49 | 38.81 |
Sample 1
| Minerological phases of Manganese identified | Manganese (wt %) | Manganese (wt %) obtained classically |
| Haussmanite, bixbyite, braunite, and ankerite | 36.34 | 36.40 |
Sample 2
| Minerological phases of Manganese identified | Manganese (wt %) | Manganese (wt %) obtained classically |
| Haussmanite, bixbyite C, bixbyite, braunite, todorokite and pyrolusite | 51.54 | 52.04 |
Conclusion:
The above results show the mineralogical phases identified and manganese concentration quantified from it to be nearly identical to what obtained following wet classical analysis. Thus quantitative powder XRD analysis provides mineralogy results that maybe applied for quality control in manganese smelters. Even though different ore compositions may satisfy the grade requirements of the ore, determination of actual phases or minerals present in the ore will dictate its smelting process parameters. The results allow the reliable prediction of smelter operation parameters such as energy consumption of the furnace and the amount of reducing agent. Thus we have shown here that powder XRD may be used to characterize various phases present in manganese ores and will be beneficial for ore quality control and optimizing smelter condition.
Contributed by Dr. Satirtha Sengupta under the guidance of Prof. Barun Kumar Gupta