Fuel pre-granulation for reducing NOx emissions from the iron ore sintering process

Abstract

This study considered the effects of a granular fuel distribution state on the NOx emissions during the sintering process. The results show that fuel pre-granulation technology can be applied to wrapping fuel inside granules to form a double-layered granular structure. Because the in-diffusion of O2 is restricted in granules, the fuel inside the granules is burnt in a relatively low O2 atmosphere, which is conducive to inhibiting the conversion of fuel-N to NOx. Meanwhile, part of the generated NOx is reduced to N2 by CO during the out-diffusion process. Consequently, using fuel pre-granulation minimises the concentration of NOx emissions and fuel-N conversion rate. Sintering experiments confirmed that using pre-granulation reduced the concentration of NOx from 425ppm to 319ppm and the fuel-N conversion rate from 59.7% to 49.4% compared with conventional granulation. Therefore, controlling the fuel combustion behaviour by regulating its distribution in granules is an effective measure to reduce NOx emissions.