Analysis of manganese smelting in steelmaking

Manganese is added to most grades of steel in the ladle as ferromanganese to improve the mechanical properties of the steel. After steelmaking, slag-metal equilibrium with respect to Mn is attained with the final Mn levels typically being 0.1 to 0.3 percent. It is theoretically possible to provide significant amounts of Mn to steel by adding manganese ore during steelmaking, for example in a BOF or Q-BOP, and smelting it using principles similar to bath smelting for producing iron. An energy and materials computer program was developed to analyze the process. The effect of the FeO content, basicity and amount of the slag on the process efficiency was determined. For example, for B = 4, %FeO = 15 percent and 100 kg/t of slag, 20 kg of ore will increase the residual Mn to over 0.65 percent from the normal level of 0.15 percent. The decrease in scrap melting, increased post combustion or fuel addition (coke or coal) required to supply the energy for reduction are given. The addition of manganese ore to an electric furnace and blast furnace is also analyzed. A simple economic model indicates that the process may be more economical, in some circumstances, than adding FeMn to the ladle with savings of up to $1 to 2/t of steel possible.