DEGREE OF PREREDUCTION WITHOUT COKE CONSUMPTION IN INDUSTRIAL FURNACES

In the HC FeMn production, better utilisation of coke and electric power is vital for reducing the production costs. The higher manganese oxides in the charge are reduced to MnO in the prereduction zone, where also the Boudouard reaction is active. These gas-solid reactions are to a large extent decisive for the total con-sumption of both coke and electrical power in ferromanganese production. In the present work formulas for calculating the Degree of prereduction have been developed for industrial practice. It shows that the typical Degree of prereduction is between 10-40%, but it may in good periods be as high as 60%. Statistical analysis has been done in order to find how various operational parameters influence the Degree of prereduction. A few parameters were observed to have an effect on the prereduction. Comilog ore definitely had a positive influence on the prereduction, Comilog sinter and Mamatwan ore probably had a positive influence on the prereduction, all in relation to the average prereduction in the selected periods. Meanwhile, Asman ore def-initely, % H2O in raw materials and increasing Hd probably, had a negative influence on the prereduction. The findings for these raw materials were very much in coherence with the results of laboratory scale exper-iments performed, where the CO-reactivity of different ore materials was studied. 1