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 oxides as a function of several operating variables. The reaction rates were derived using the experimentally measured time for complete reaction t R of the iron oxides. The value of t R was the same for both pure synthetic wustite and hematite having equal moles of oxygen per unit melt cross-sectional area. The reduction rates of iron oxide were determined 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 were 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 coefficient 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 it was above 0.95 wt-%C. The rate was also unaffected by the position and state of the oxides, or by the intensity of argon injection into the bath. It was determined that the rate limiting steps of the process were interdiffusions of oxygen and carbon in the multiphase foam present on the melt surface. Industrial applications of the present investigations were studied by carrying out several experiments with commercial iron ore and metallised pellets.