Abstract：adial distribution of burden is determined by the position of particle landing during charging in blast furnace. In practice, the landing points of particles are not the same because of their different density, size and shape. In published papers, there are some problems such as: neglecting the drag force of gas, choosing the improper density and using irrelevantly the drag force formula, so the difference between calculation and practice is large. In this paper, the grain gravity, buoyancy and gas drag force are considered. In addition, the mathematical model is developed and the movement trajectory of a particle in free zone is computed. According to charging radius variation with different burdens in their range of grain diameter and the size of drag force, the influence of gas drag force is important when computing the burden trajectory for achieving the optimal burden distribution.
