Minerals & Metallurgical Processing

, Volume 21, Issue 1, pp 9–16 | Cite as

Nitrogen oxide (NOx) emission reduction during pellet induration by fuel addition to the green pellets and decreased excess air

  • J. Engesser
Technical Paper


A research project was undertaken to determine if coal addition to fluxed-magnetite prefired pellets would reduce nitrogen oxide (NOx) emissions during pellet induration. Iron-oxidation-rate tests, coal-oxidation-rate tests and calcinations-rate tests were conducted in a laboratory furnace to determine the amount of coal necessary to provide adequate heat for limestone calcination without producing detrimental effects to magnetite oxidation. Pilot-scale pot-grate tests were then performed both with and without coal in the prefired pellets to verify pellet-quality parameters and nitrogen oxide emissions. The off-gas during each pot-grate test was analyzed for NOx, CO2, CO, SO and O2. There was approximately a 10% reduction in NOx emissions with coal addition during the normal pot-grate firing cycle. There was a 75% reduction in NOx emissions during firing cycles that used 25% to 75% excess air during firing rather than the normal 300% excess air.

Key worrds

Taconite processing Pellet induration Nitogen oxide emmisions Coal addition 


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  1. Carter and Benson, 1984, “Combustion Modification Tests on a Subscale Cement Kiln for NOx Reduction,” EPA-600/S7-84-075.Google Scholar
  2. Davis, R., 1995, “Thermal NOx Formation in a Taconite Pellet Rotary Kiln,” Minnesota Department of Natural Resources–Division of Minerals, March 1995.Google Scholar
  3. Garg, A., 1992, “Trimming NOx,” Chemical Engineering, November, pp. 122–129.Google Scholar
  4. North American Mfg. Co., 1993, “NOx Reduction,” Handbook Supplement 7–93.Google Scholar
  5. Parkinson, Fouhy and Moore, 1994, “NOx: US plants take aim at a moving target,” Chemical Engineering, January 1994, pp. 28–31.Google Scholar
  6. US-EPA, 1998, “The Regional Transport of Ozone,” EPA-456/F98-006, Sept 1998.Google Scholar
  7. Walters et al., 1999, “Time-variability of NOx emissions from portland cement kilns,” Environmental Science and Technology, Vol. 33, No. 5, pp. 700–704.CrossRefGoogle Scholar
  8. Wood, S., 1994, “Select the right NOx control technology,” Chemical Engineering Progress, January, pp. 32–38.Google Scholar
  9. Zahl, 1995, “NOx Formation in Methane Combustion with High Temperature Air,” Minnesota Department of Natural Resources–Division of Minerals, Nov. 1995.Google Scholar
  10. Zahl, Hass and Engesser, 1995, “Formation of NOx in Iron Oxide Pelletizing Furnaces,” Minnesota Department of Natural Resources–Division of Minerals, Sept. 25, 1995.Google Scholar

Copyright information

© The Society for Mining, Metallurgy & Exploration 2003

Authors and Affiliations

  • J. Engesser
    • 1
  1. 1.Minnesota Department of Natural ResourcesDivision of Lands and MineralsHibbingUSA

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