The dissolution of synthetic and industrial zinc ferrite was studied in HNO3, HClO4 and H2SO4 solutions, at temperatures ranging from 75°C to 95°C and in the presence of an excess of Fe2+, Fe3+ or Zn2+ ions. The rate constant describing this dissolution process was obtained by using a surface-reaction controlled, shrinking core model, which yielded good results. The dissolution rate zinc ferrite depends on the square root of the hydrogen ion activity in H2SO4 and HClO4 solutions. The apparent activation energy for the dissolution equals 74±2 kJ/mol in H2SO4, 47±22 kJ/mol in HClO4 and 37±16 kJ/mol in HNO3. The order of the rate constant was 0.6 in the Fe2+ and -0.5 in the Fe3+ concentration. The rate constant for the dissolution of industrial zinc ferrite was 20-50% lower than for synthetic zinc ferrite. The presence of 85 g/l Zn2+ in the leach solution retarded the dissolution rate of zinc ferrite. A dissolution mechanism is proposed which qualitatively explains the results obtained.
ASJC Scopus subject areas
- Metals and Alloys
- Industrial and Manufacturing Engineering
- Materials Chemistry