Pan granulation

Pan granulation of ammonium nitrate also has been developed commercially (16,17). Essentially water-free melt (<0.5%moisture) is sprayed onto a cascading bed of fines (usually cmshed recycle) ia a tilted, rotatiag pan. Production of 18—20 t/h is common. Product made ia this manner is said to require ao conditioning. The pan is an excellent size classifier, making it easy to produce granules of any desired size from 1 to 11 mm diameter. 

Advantages of pan granulation are ease of granule size control, hardness of granule, and simplicity of pollution control. 

O. Skauh, "Pan Granulation of Ammonium Nitrate and Urea," paper presented at the 168th National Meeting of the Mmerican Chemical Society, Adantic City, N.J., 1974. 

In the pharmaceutical industiy, pan granulators are still widely used for coating application. Pans are suitable for coating only relatively large granules or tablets. For smaller particles, the probability of coalescence is too high. 

Inspection of this equation shows that in the course of the snowballing growth the size distribution curves at various times are simply shifted toward the right on the pellet size scale without any change in their shape, as demonstrated by Capes (C2) for sand pellets snowballed in a pan granulator (Fig. 13). 

Pan granulation is not expensive but has the drawback that the product has a rather wide size distribution, necessitating a screening operation afterwards. The diameter of the beads can vary from 1 mm to 20 mm. 

The sulfur-coating technique may be applied to fertilizers other than urea. Experimental work has included a coating of DAP, potassium chloride, potassium sulfate, and various compound fertilizers, including a pan-granulated urea-potassium chloride product of 32-0-16 grade. 

Figure 111. Schematic representation of a pan granulator operating at equipped...

Utilization of the pan granulator was first reported in Germany in 1953 for the granulation of ordinary superphosphate. 

PAn has been integrated into other structures (polyethylene, polyterephthalate, polyester, and polystyrene) by soaking in monomer solutions and then exposing to acidic oxidant (FeCl3) solutions 41 Results suggest that the polymers were swollen by the aniline monomer and that polymerization occurred within these swollen media to produce dispersed PAn granules. Conductivities on the order of 10 1 S cm-1 were obtained. 

Utilization of the inclined-pan granulator in the fertilizer industry was first reported in Germany in 195 3 for the granulation of ordinary superphosphate and the first documented application of suspended-solids agglomerators was in the early 1960s using a spouted bed [B.48]. 

Fig. 6.6-5 left) Diagram of the wall and bottom scrapers in a pan granulator right) sketch of the particle motion that is assisted by the position of the bottom scrapers [B.97]... 

Agglomerierteller (Kinetics of agglomeration for the simulation of agglomeration processes in the pan granulator)... 

Fig. 6.6-5 left) Diagram of the wall and bottom scrapers in a pan granulator right) sketch of the particle motion that is assisted by the position of the bottom scrapers [B.97] Fig. 6.6-6 Photograph of a 4.6 m diameter pan showing the still-unadjusted vane-type plow scrapers (E) that are individually mounted on a support structure (D), which moves with the tilt of the pan (courtesy Feeco, Green Bay, Wl, USA)...

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