The results of numerical simulations of particle sticking behavior near the throat of a low-NOx axial-swirl burner in a 600-MWe bituminous coal burned boiler are presented. A comparison of simulation results with measurements using a probe with hot-film sensors shows that the numerical model offers a reasonable description. Calculated results of slagging show that slag build-up is substantial near the throat of the designed burner and that the sticking-particle ratio is as much as 33.2%. Because central and primary air streams remain unchanged, the mass flux of the inner secondary air is 3.25 kg s(-1) while that of the outer secondary air is 12.16 kg s(-1); however, the sticking-particle ratio can still be lowered to as little as 9.6%. By adjusting the outer secondary air blade angle to 15 degrees, the sticking-particle ratio can be further lowered to 8.73%. (C) 2010 Elsevier Ltd. All rights reserved.