Granulators rotating drum

Rotating drum granulators have length to diameter ratios of 2-3, speeds of 10-20 rpm, pitch as much as 10°. Size is controlled by speed, residence time, and amount of binder 2-5 mm dia is common. 

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,... 

Other pigment blacks and the rubber blacks are compacted by granulation. Two processes are used dry and wet pelletization. Dry pelletization is a simple, energysaving method, but it does not work with all types of carbon black. It is mainly used for color blacks. Dry pelletization is carried out in rotating drums, where the powdery carbon black rolls to form small spheres. 

A. Heim, T. Gluba, A. Obraniak, Bed dynamics during granulation in rotating drums, In Proceedings of the 7th International Symposium on Agglomeration, Albi, 2001. 

P.A.L. Wauters, R. van de Water, J.D. Litster, G.M.H. Meesters, B. Scarlett, Growth and compaction behaviour of copper concentrate granules in a rotating drum, Powder Technol. 124 (2002) 230-237. 

Fig. 11.18 Di agram of a agglomeration system forthe granulation of furnace black in a rotating drum [11-12]...

Electrostatic separation, of a granulated mixture of polymers from electronic products, can separate polymers of similar density. The particles are charged by passing through an inclined rotating drum, then separate during free fall between two charged plates. 

In another technique, molten urea is sprayed at 148 °C onto cascading seed granules (<0.5 mm) in a rotating drum until they grow into product sized particles (2-3 mm). Heat released by the solidifying melt is removed primarily by evaporation of a fine mist of water sprayed into air that is passed through the granulation drum (Shirley, Nunelly and Cartney, 1982). 

Heuristic 51 Particle-size enlargement. Use compression with rotary compression machines to convert powders and granules into tablets of up to 1.5 inches in diameter. Use extruders with cutters to make pellets and wafers from pastes and melts. Use roll compactors to produce sheets from finely divided materials the sheets are then cut into any desired shape. Use rotating drum granulators and rotary disk granulators with binders to produce particles in the size range of 2 to 25 mm. 

---