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Study of Melting Process of Dri, Product of Tunnel Kiln, in Induction Furnace

Heydari Sereshk, Javad | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52130 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Halali, Mohammad
  7. Abstract:
  8. Due to the expanding trend of using induction furnaces in Iran, the production of sponge iron at a smaller scale by Midrex method has become important. Since induction furnaces cannot benefit from the oxygen blower and foam slag like arc furnaces, the induction furnace charge should be of a higher quality. In addition, as the oxidation conditions in induction furnace are higher in comparison to arc furnaces, re-oxidation control of the induction furnace is essential. Making briquettes is one of the processes, which reduces re-oxidation during melting and since the briquette remains floated on the melt until complete melting, the lower level of briquette's contact with ambient atmosphere and higher melting rate lead to the lower oxidation rate and melting losses. In order to investigate these items in the present study, using two kinds of induction furnaces including high and medium frequency furnaces was considered. In the 450 kHz furnace, the effect of density, metallization amount, slag maker composition and atmosphere type on the furnace efficiency (dependent on the oxidation rate of the charge and melting during the process) and melting time, and in the 8 kHz furnace the effect of density, dimensions and briquette geometry on melting rate, energy consumption and production efficiency were investigated. The results of melting processes in both furnaces were evaluated by weight analysis and XRF. Logical relationship created between variables and results by using mathematical models and equations. The lowest melting time under neutral gas was 685 seconds, which was obtained from melting 35 gr briquettes at 5.98 (g/cm3) and 93.94% metallization. The highest production efficiency under ambient atmosphere was 78.42%. Using graphite crucibe and flux also reduced melting time to 388 seconds and increased production efficiency to 93.14%. By increasing briquette density from 2.99 to 4.48 g/cm3 in the 8 kHz furnace, production efficiency for melting 10 kg briquettes increased to 80.66%. In addition, the highest melting rate at each loading stage (500 g) obtained from melting briquettes with a diameter of 2.07 cm, equal to 18.56 g/s
  9. Keywords:
  10. Tunnel Kiln ; Induction Furnace ; Sponge Iron ; Melting Sponge Iron ; Melt Reoxidation ; Induction Heat

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