Balling and granulation equipment

Rotating drums, disks, and to a lesser extent, cones are used in continuous large-scale balling of iron ores (E3). A pelletizing disk of industrial type is shown in Fig. 1. Fertilizers are granulated in twin-shaft pug mills, drums, 

The published data on design, scale-up, and performance characteristics of the balling drum are substantially fewer than those available for the disk. This presumably reflects the fact that the latter is a more versatile agglomer-ator it is, however, more difficult to control for a stable operation. 

The performance of the pelletizing disk depends on its size, speed, angle to the horizontal, collar height, positions of the feed chutes, water sprays and scrapers, and the feed throughput. The critical speed at which the balls no longer roll down but stick to the collar wall under centrifugal force is given by (P3) 

Since densification of the granules in the drums and disks is brought on by gravitational force, there is a definite upper limit on both the rate and the extent of compaction that is attainable. This is specially true in the case of fine solids. In general, compaction of the granules occurs concurrently with their growth, and it is seldom possible to exercise independent control over these two actions of the pelletizer. 

Drums and disks are not suitable for the agglomeration of sticky and highly plastic materials, for example, clays or solids containing colloids and very fine components. 

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