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Mathematical model of direct reduction in multilayer pellets made of metallurgical dust in a rotary hearth furnace

Research paper by Ying Liu, Wen Zhang, Zhongmu Zhou, Yang Xu, Long Wang

Indexed on: 19 May '17Published on: 17 May '17Published in: Heat Transfer—Asian Research



Abstract

A mathematical model of direct reduction of metallurgical dust pellet layers has been established in a rotary hearth furnace. The effects of radiation shielding of the upper layer to lower layer and the heating effects of the hearth were considered in the model. The control equations of the model were discretized into algebraic equations based on the control volume integration method and numerically solved by the alternating direction implicit method. The effects of pellet arrangement, furnace temperature, and the height of the pellet layer were investigated by the model. The results show that staggered arrangement of metallurgical dust pellets can improve average temperature of pellet layer. Thus, the degree of metallization and zinc removal rate of the pellet layer are improved. With the increase of furnace temperature, degree of metallization increases rapidly. Compared with iron oxide reductions, furnace temperature has less effect on zinc removal rate. With the height of pellet bed increasing to four layers, both degree of metallization and zinc removal rate of the fourth layer are slightly higher than that of the third layer. After heating for 15 min, extending heating time has little influence on zinc removal rate of each layer.