Evaluation of NOx-Reduction Measures for Iron-Ore Rotary Kilns
Journal article, 2020

The grate-kiln process is employed for sintering and oxidation of iron-ore pellets. In this process, a fuel (typically coal) is combusted with a large amount of excess air in a rotary kiln, and the high air-to-fuel ratio leads to significant NOx formation. The current Article is an assessment of NOx reduction measures that have been tested in pilot-scale and in full-scale by the Swedish iron-ore company Luossavaara-Kiirunavaara Aktiebolag (LKAB). The results show that the scaling between the full-scale kiln and the pilot-scale kiln is crucial, and several primary measures that reduce NOx significantly in pilot-scale achieve negligible reduction in full-scale. In the investigated full-scale kiln, thermal NOx formation is efficiently suppressed and low compared with the NO formation from the fuel-bound nitrogen (especially char-bound nitrogen). Suppressing the NO formation from the char-bound nitrogen is difficult due to the high amounts of excess air, and all measures tested to alter mixing patterns have shown limited effect. Switching to a fuel with a lower nitrogen content is efficient and probably necessary to achieve low NOx emissions without secondary measures. Simulations show that replacing the reference coal with a biomass that contains 0.1% nitrogen can reduce NOx emissions by 90%.


Rikard Edland

Chalmers, Space, Earth and Environment, Energy Technology

Neil Smith

University of Adelaide

Thomas Allgurén

Chalmers, Space, Earth and Environment, Energy Technology

Christian Fredriksson


Fredrik Normann

Chalmers, Space, Earth and Environment, Energy Technology

Denver Haycock

Brigham Young University

Colson Johnson

Texas A&M University

Jacob Frandsen

Brigham Young University

Tom Fletcher

Brigham Young University

Klas Andersson

Chalmers, Space, Earth and Environment, Energy Technology

Energy & Fuels

0887-0624 (ISSN) 1520-5029 (eISSN)

Vol. 34 4 4934-4948

Reduced CO2 emissions from LKABs rotary kiln process – a study of the effect of alternative fuels

Swedish Energy Agency (2012-009098), 2013-05-01 -- 2016-04-30.

LKAB (Roteringsugnsprocess), 2013-05-01 -- 2016-04-30.

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Sustainable development

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Energy Engineering

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