Abstract:
The two main furnaces in the world applied to burn pellets are the travelling grate and the rotary kiln. Although the raw materials to produce the pellets may be similar, these furnaces have their peculiarities, generating pellets with different quality. In this context, the present work investigated two pellets as-produced and after reduction with the aim to compare and correlate the differences imposed by the use of the travelling grate and rotary kiln furnaces. On the one hand, the pellet produced in travelling grate presented a higher porosity, and consequently a higher reducibility, due to the possibility of adding a larger amount of anthracite. On the other hand, the pellet strength is lower as compared to the pellet produced in rotary kiln, not just because of the porosity and cracks, but also due to the better homogenization and finishing touches that the rotary promotes in the pellets. Besides the differences in physical characteristics, a difference in the microstructure after reduction was observed. In the reduction process, the pellet produced in the travelling grate was represented by topochemical model, while the one produced in the rotary kiln was based on the reduction starting by the inner cracks and pores.