Kinetic Investigations of SiMn Slags From Different Mn Sources

Abstract

The kinetics of MnO and SiO2 reduction were investigated for Silicomanganese (SiMn) slags using a Thermogravimetric analysis (TGA) between 1773 K and 1923 K (1500 °C and 1650 °C) under CO atmospheric pressure. The charge materials were based on Assmang ore and HC FeMn Slag. Rate models for MnO and SiO2 reduction were applied to describe the metal-producing rates, as shown by the following equations: $$ r_{\text{MnO}} = k_{\text{MnO}} \times A \times \left( {a_{\text{MnO}} - \frac{{a_{\text{Mn}} }}{{K_{\text{T}} }}} \right) $$ $$ r_{{{\text{SiO}}_{2} }} = k_{\text{SiO}_{2}} \times A \times \left( {a_{{{\text{SiO}}_{2} }} - \frac{{a_{\text{Si}} }}{{K_{\text{T}} }}} \right). $$ The results show that the choice of raw materials in the charge considerably affected the reduction rate of MnO and SiO2. The highest reduction rate was found to be from charges using HC FeMn slag. The difference in the driving forces was insignificant among the SiMn slags, and the similar slag viscosities could not explain the different reduction rates. Instead, the difference is attributed to small amounts of sulfur and the amount of iron in the charge. In addition, the rate models were applicable to describe the reduction of MnO and SiO2 in SiMn slags.