Off-Gas Characteristics for Varying Conditions in the Prereduction Zone of a Ferromanganese Furnace –A Basis for Energy Recovery

The off-gas characteristics of a ferromanganese furnace is largely determined by the behaviour of the manganese ore in the prereduction zone. There are two main features that determine the effect, being the oxygen level of the ore, and the kinetics of the reaction between the solid ore and the CO(g) in the furnace gas. Mass and energy balances were used to estimate the variations in off-gas characteristics, including amount, composition, and temperature, for various conditions that may occur in a prereduction zone. The investigated systems were the production of HC FeMn relying on Comilog- or Nchwaning-ore as the manganese source, respectively. Results obtained from laboratory investigations of the prereduction behaviour of the ores with varying particle size and CO/CO2 ratio in the reducing atmosphere were used as input to the calculations.