Granulation Fluid Drum

Dali Aglio, L., Fluid Drum Granulation for Ammonium Nitrate, Kaltenbach-Thuring, The International Fertiliser Society, Proceeding 415, 1998 (www.fertiliser-society.org/Proceedings/Prc415.HTM). 

Tumbling granulators Drums Discs 0.2-20 Moderate 0.5-800 tons/h Very spherical granules Fluid-bed or rotary kiln drying Fertilizers, iron and other ores, agricultural chemicals... 

Fig. 10.21 Flow sheet of a fluid drum granulating (FDG) process for the coating or fattening of granules with sulfur and/or purge solution (courtesy Kaltenbach-Thuring, Beauvais, France).

Fig. 6.6-30 shows cross sections of broken melt-coated fertilizer granules [B.97]. In this case, the cores of conventionally granulated (by tumble/growth agglomeration. Section 6.6.1) TSP (triple super phosphate) were melt-coated with sulfur to provide an additional nutrient for sulfur-deficient soils and/or obtain a slow-release fertilizer. Fig. 6.6-31 is the flow diagram that is used for this process. The centerpiece of the system is the so-called fluid drum granulator (FDG). 

The fluid drum granulator (Fig. 6.6-32) is one vendor s design to most efficiently achieve a uniform coating. Other coaters can be also used for the task. The fluid drum coater is a cylindrical horizontal drum, rotating around its axis, and fitted with special... 

Fig. 6.6-34 Flow diagram of a system using the fluid drum granulator (FDC) for the production of granulated degradable sulfur for agricultural use (courtesy Kaltenbach-Thuring, Beauvais, France)...

The effect of fluid penetration rate and the extent of penetration on granule size distribution from drum granulation experiments is illustrated in Fig. 20 (since no example for fluidized bed granulation is available). From Fig. 20, it is clear that for fluids with a similar extent of penetration, increasing the penetration rate increases the average granule size for various levels of liquid loading. 

Drum and belt drying and solidification systems are discussed below. This equipment is capable of forming granular products directly from fluid pastes and melts, without intermediate preforms, by drying or solidification on solid surfaces. Drum and belt systems offer an alternative to the dispersion methods (such as the prilling of sulphur, fertilizers and resins and the spray granulation of clays) described in Chapter 7. 

Antioxidants in the form of mixed tocopherols are added to the phospholipid/ hexane mixture. The phospholipids are then desolventized through the use of a drum desolventizer followed by a fluid bed dryer. Solvent residuals in the dried product are less than 5 ppm. The dried flakes are placed in storage bins. From there, the flakes are ground into powder and then agglomerated into granules. The acetone-insoluble content of the finished product is claimed to be in the range of 90-99.9%. 

As an example of Washburn approaches, the effect of fluid penetration rate and tne extent of penetration on granule-size distribution for drum granulation was shown by Gluba et al. [Powder Hand, ir Proc., 2, 323 (1990)]. Increasing penetration rate, as reflected by Eq. (21-98b), increased granule size, and decreased asymmetry of the granule-size distribution as shown in Fig. 21-101. 

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