ON THE VARIABLE DISSOLUTION KINETICS OF ZINC FERRITE IN ACID-MEDIA

Different magnetic fractions of narrow-sized industrial residues of zinc ferrite [(Zn1-x, Fe(x)2+)Fe23+O4, x less-than-or-equal-to 0.4] have been leached with 1 mol/L H2SO4 at temperatures ranging from 348 to 368 K. Fractions with excess iron, which exhibit higher magnetic susceptibility, are found to dissolve faster. It is believed that the lattice substitution of Zn by Fe2+ in the more magnetic ferrite fractions creates crystal defects and renders the ferrite more chemically reactive. An interfacial electrochemical reaction mechanism has been advanced to account for the effects of solid state composition and solution composition on the variation of the dissolution kinetics of zinc ferrite. Finally, the practical implications of these findings on the industrial leaching of zinc ferrite are briefly addressed.