**6. Conclusion**

*Iron Ores*

essential.

the reducibility.

life cycle.

than 15–30% MnO, is discarded.

secondary products such as cement.

**5. Hydrogen plasma**

i.e., bixbyite (Fe, Mn)O3 mineral.

and/or complex mixtures phases.

mechanical properties of the agglomerate.

separates as magnetic particles. However, the feasibility of the upgrading process becomes questionable when both iron and manganese oxides are in associated form,

In the present study, lean manganese ore was collected from Joda valley, Odisha, India. The ore is in fine form and is being discarded as waste at the mines site itself. The initial assessment of the ore through wet chemical analysis indicated that the ore contains about 17% of alumina and 9% of silica. The Mn content in the fines is about 12%, which falls into the manganiferous category. The reduction studies of such briquettes evidenced the formation of hercynite, galaxite, fayalite-manganon, and spessartine phases at different temperatures. These phases lower the reducibility of the ore and also deteriorate the physical and

Here an attempt was made to utilize these fines directly in thermal plasma, avoiding any agglomeration. Smelting of such ores by using other technologies results in poor Mn recovery (≈30%) and high FeO loss into slag; flux addition was

The smelting of ore with flux addition targeting melilite and mayenite slags in ionizing atmosphere improved Mn recovery and was 80% maximum. Although plasma arc provides high energy flux, the slag chemistry also governed the process kinetics. By adjusting slag chemistry to a too basic slag lowered the activity of silica and alumna; however, the formation of high melting silicate compounds such as dicalcium silicate and tricalcium silicate increases the viscosity of the slag. The flowability of such slag hinders carbon contact with metal oxides and hence lowers

In the current scenario, ferromanganese production follows rich slag and discard slag practices. The rich slag retained in primary smelting (low fluxing) is further smelted in another step to produce silicomanganese or ferro-silicomanganese. In discard slag practices, the slag retained in primary smelting, which contains less

The present study refers to the discard slag practice followed by plasma smelting with the highly basic slagging operation. As the ore contains high alumina, primary smelting similar to rich slag practice will result in slag with alumina bearing compounds, which will be difficult to reduce in the secondary smelting for obtaining silicomanganese. Moreover, the cost of smelting these high melting compounds will increase reductant, energy consumption, and also lower the furnace refractory

The extraction of metals from these types of complex ores in single-stage smelting operation should be chosen in such a way that the slag can be used in

In iron making, coke is used as a heat source and reductant. The application of plasma in iron making lowers COX emission for being used as plasma as a heat source. The reducibility of metal oxides by solid carbon or CO gas is lower than that of H2. The use of methane as plasma forming gas is beneficial over argon or nitrogen from a cost perspective. However, ecofriendly gas emission in iron making is only

As an alternative, these ores are subjected to smelting for obtaining FeMn alloy with low Mn content. It is a cost-saving operation, and smelting operations can be carried out even in BF. The complexity arises for such ores with high gangue amount, which affects the extraction kinetics by forming silicates, aluminates,

**102**

The importance of plasma in iron making is discussed considering different types of ore minerals and its various aspects of processing. The freedom in size, composition, and smelting conditions required for complex ore minerals fits into the processing of iron ore in thermal plasma. The use of coke as a heat source in conventional iron making processes can be eliminated with the application of thermal plasma. The recovery rate and purity level in hot metal extracted from complex mines waste is noticeable higher by using thermal plasma. The future eco-friendly hydrogen plasma processing is of interest. Moreover, the use of hydrogen plasma can result in carbon-free metal/alloys, which can lower production costs by avoiding decarburization.
