Influence of furnace temperature and non-uniform heat flux density on direct reduction process of newly designed carbon containing pellet

Abstract

In this study, innovative ellipsoid pellet with craters on its surface was designed, and the direct reduction process was compared with ellipsoid (without craters) and sphere pellets. In addition, furnace temperature and uneven heat flux density effects on the pellet direct reduction process were also studied. The results show that ellipsoid pellet is better than that of spherical pellet on metallization ratio. However, under the condition of non-uniform heat flow, the ellipsoid pellet final metallization rate and zinc removal rate were lower. Although the heat transfer effect of ellipsoid pellet with craters was not improved significantly, the metallization rate and zinc removal rate were found improved, which will have a cumulative effect on the pellets direct reduction process in rotary hearth furnace. Under varying furnace temperature conditions, the pellet temperature was higher than that of the constant furnace temperature. After 1200 s, pellet Fe concentration increased to 123.6%, metallization rate and zinc removal rate increased to 113.7% and 102.2%, respectively. These results can provide references for the carbon-containing pellet design used in rotary hearth furnace.

Keywords

rotary hearth furnaces / carbon containing pellets / direct reduction process / heat and mass transfer / mathematical model

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