KINETICS OF IRON-OXIDE REACTIONS IN BATH SMELTING PROCESS

Mechanisms of iron oxides reactions with Fe-C melts are proposed here, after analysing experimentally determined reduction rates of iron oxi des as a function of several operating variables, The reaction rates w ere derived using the experimentally measured time for complete reacti on t(R) Of the iron oxides. The value of t(R) was the same for both pu re synthetic wustite and hematite having equal moles of oxygen per uni t melt cross-sectional area. The reduction rates of iron oxide were de termined as a function of melt cross-sectional area at temperatures in the range 1723-1923 K. Four different melts of cross-sectional area 1 .38 x 10(-3), 2.16 x 10(-3), 3.83 x 10(-3), and 10.23 x 10(-3) m(2) we re used. The average order of the overall reaction of the process was 0.66. The apparent rate constant increased with increasing temperature and the experimentally determined apparent activation energy coeffici ent was 78.05 +/- 18.78 kJ (mol O)(-1). The carbon concentration of a bath had no effect on the reaction rate of the oxides at 1723 K when i t was above 0.95 wt-%C. The rate was also unaffected by the position a nd state of the oxides, or by the intensity of argon injection into th e bath. It was determined that the rate limiting steps of the process were interdiffusions of oxygen and carbon in the multiphase foam prese nt on the melt surface. Industrial applications of the present investi gations were studied by carrying out several experiments with commerci al iron ore and metallised pellets.