Comparative study of agglomeration in rotating disk and pellet mill

Abstract

The subject of agglomeration is little studied in the graduate courses, creating a relative difficulty of finding general data about existing processes. In this way, seeking to contribute to the progress of this field of knowledge, data and general aspects were collected for the selection of agglomeration equipment, comparing the rotating disc tumbling processes and the low compression method using a pelletizing equipment, with silica sand, 100% passing through 75um sieve, to reduce the composition variations that could interfere in the comparison of the agglomeration methods provided by the equipment. Among the comparisons of binder formulations, bentonite was employed at 1% in the composition and 10% initial moisture. In the case of the disc, water added during the process reached 19,5% of moisture. In the pelletizer, the moisture reached 13%. The comparative results demonstrated that for the rotating disc process the mixture mustn’t have plasticity that can deform the pellets during the operation; besides, this process used 6,5% more water, causing a larger energy expenditure for drying. On the other hand, the energy expenditure of only the disc machine was 10 times lower than the energy expenditure of the pellet mill. The process yield was lower, reaching a recycle ratio of 1:3 and promoting greater porosity in the product. The pelleting showed greater acceptance of plastic mixtures. The obtained product had greater mechanical strength, but showed lower porosity. The process yield was better, reaching 50.5% and the productivity was 10 times higher than that of the rotating disc.

Keywords: agglomeration; pelletizing; compaction; comparative study; rotating disc.