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Pre-reduction of Manganese Ore by Natural Gas for Ferromanganese Production

Cheraghi, Alireza | 2020

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 53632 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Yoozbashizadeh, Hossein; Safarian, Jafar
  7. Abstract:
  8. Pre-reduction of some manganese sources (low-grade Venrach and Godar-Sabz ores, high-grade Comilog ore, pellet, pure oxide) by methane gas has been investigated in this research. HSC-Chemistry and FactSage software were used for thermodynamic study of the process. Thermodynamic results indicated that methane may progress to manganese carbide formation, and the reduction process can run autonomously involving less carbon dioxide emission comparing to common ferromanganese process. Several techniques including XRF, XRD, in-situ XRD, SEM-EDS, and thermogravimetry were used in sample characterization and experiments. In addition to the thermal decomposition reactions which were affected by oxygen partial pressure, reactive diffusion, which was influenced by particle size, played a main role in the calcination trials. Reduction process and carbide formation were encouraged by reactive diffusion of manganese and iron oxides. The exothermic reduction of manganese oxides started prior to the reduction of coexisting iron oxides, and the apparent activation energy for the reduction of manganese oxides to MnO was 71.72 kJ/mol. While increases in both temperature and methane in the reduction atmosphere intensified the reduction severity, formation of manganese silicate network at high temperatures lowered the reduction progress; the best pre-reduction results were achieved at 1100 ⁰C with 24% Mn carbide formation. Even low quantities of some bothersome phases in the manganese sources could affect the reduction process adversely. However, soot formation and gas blockage was the main reason for slowing down the reduction. In addition to the porosity content in the manganese source, reducibility was highly affected by porosity characteristics
  9. Keywords:
  10. Manganese Oxide ; Natural Gas ; Methane ; Reduction ; Pre-Reduction Process ; Ferromanganese

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