Manganese is a very important alloying element for steel production. So far, in blast furnaces or submerge arc furnaces, ferromanganese has been made from manganese ore for producing alloy steel. Although alloying steel with ferromanganese is advantageous for steel production with high manganese content and it is easy to accurately control the manganese content, the requirement level for raw materials is very high.
Recently, there is a growing interest in direct alloying of steels by manganese ore as high-grade manganese ore needed for ferromanganese is gradually depleted and the price of ferromanganese is increasing. Direct alloying by manganese ore is a way of producing steels by smelting reduction and alloying manganese ores, coke (or anthracite), lime, etc. added to the liquid steel in steel furnaces or ladle refining furnaces.
Previous researchers found that direct alloying of steel by manganese ore in the steelmaking process of an electric arc furnace is feasible, but they all used high-grade ores with approximately 40% of Mn content for test melting.
Jang Sung Ryong, a researcher at the Faculty of Metal Engineering, has analyzed the reduction thermodynamic characteristics of manganese oxide in an electric arc furnace and the effect of several factors such as liquid steel temperature, slag basicity, manganese ore grade on the direct alloying process by low-grade manganese ore using the material thermodynamic calculation program “Factsage”.
The comparison of the theoretical analysis of Factsage and the results of the test melting for direct alloying in a five-tonne electric arc furnace shows a relatively good agreement in the contents of carbon, manganese and sulfur in the liquid steel as well as the MnO content in the slag near the end of the reduction period.
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