**Han Wei 1, Meng Li 1, Ying Li 1, Yao Ge 1, Henrik Saxén <sup>2</sup> and Yaowei Yu 1,\***


Received: 12 July 2019; Accepted: 20 August 2019; Published: 23 August 2019

**Abstract:** The lumpy zone in a blast furnace is composed of piles formed naturally during burden charging. The properties of this zone have significant effects on the blast furnace operation, including heat and mass transfer, chemical reactions and gas flow. The properties of the layers mainly include the angle of repose and porosity distribution. This paper introduces two methods, the Discharging Method and the Lifting Method, to study the influence of the packing method on the angle of repose of the pile. The relationships of the angle of repose and porosity with physical parameters are also investigated. The porosity distribution in the bottom of a pile shows a decreasing trend from the region below the apex to the center. The coordination number of the particles is employed to explain this change. The maximum of the frequency distribution of it was found to show a negative correlation to the static friction coefficient, but becomes insensitive to the parameter as the static friction coefficient increases above 0.6.

**Keywords:** pellet pile; Discrete Element Method; porosity distribution; angle of repose; coordination number
