Kinetics of Hydrogen Reduction of Iron Aluminate FeAl2O4 (Hercynite).

Hercynite is formed in copper and steelmaking slags, and also forms inclusions in steel during aluminum refining of the melt and by reaction of liquid steel with high alumina refractories. The hydrogen reduction of FeAl//2O//4 between 750 and 1050 C was studied by thermogravimetric analysis and high temperature x-ray diffraction and in situ. The reaction products were investigated by x-ray techniques and scanning electron microscopy. The activation energy of reduction is given as 45 plus or minus 3 kcal/mol. Two rate-controlling mechanisms are proposed; i. e. , diffusion of hydrogen through the PHI //F//e phase, and diffusion of the iron of the iron aluminate at the interface.