Granule production

The urea solution stream is then fed to the vacuum concentrator unit which operates at 17.3 kPa (130 mm Hg abs) and produces 88.7 wt % urea. It then goes to either two-stage evaporators if prills are made, or a single-stage unit for granule production. 

Use of plastic dmms is widespread in the chemical industry. These dmms are used for packaging Hquids, semisoHds, powders, and granulated products. 

The approach taken here is to employ standard materials characterization tests to measure the materials properties of the granulated product. With this information, the mechanism of attrition, i.e., breakage versus erosion, is determined. The rate of attrition can then be related, semi-empirically, to material properties of the formulation and the operating variables of the process, such as bed depth and fluidizing velocity. 

Fig. 1.61. Schema for the calculation of the drying time /MD for the main drying of granulated product (Fig. 4 from [1.51]).

Fig. 2.57. Drying time as a function of a periodic, thorough mixing of a granulated product.

The possible drying times for the main drying are estimated in Section 1.2.1 and complemented by examples. The decisive qualities are the heat transfer coefficient from the shelf to the sublimation front of the ice (Ktot). The heat conductivity in the product does normally not play an important part (see Fig. 1.67), except that a granulated product is dried from the surface to the center (see Fig. 1.68). The shortest possible main drying time can be estimated with 5 or 10 % error, if the dimensions of the product and the maximum tolerable TKe (e. g. -10 °C) are given (Eq. (12), (12 a-c) in Section 1.2.1). 

In Europe, Copper Phthalocyanine Blue is usually supplied as a powder or as a granulate. The granulated product is somewhat less dusty but also more difficult to disperse. In the USA, P.B.15 3 also continues to be offered in the form of flushed pastes to be incorporated into oil-based printing inks. These pastes offer improved pigment dispersion and frequently afford more glossy and transparent prints. 

M. Halstensen, P. de Bakker, K.H. Esbensen, Acoustic chemometric monitoring of an industrial granulation production process - a PAT feasibility study, Chemom. Intell. Lab. Syst., 84, 88-97 (2006). 

Bulk powder properties are important in understanding the handling properties of an excipient or a granulated product. Common parameters measured are bulk and tap density. From these values the compressibility can be calculated using the following ... 

Determine the moisture content of the nongranulated product with the granulated product. 

Table 4 A and B Influence of Operating and Material Parameters on the Granulated Product...

Figure 3 displays the results for a wet granulated product run at three speeds and three forces in production. The same speeds and similar forces were used on the Presster. Thirty tablets were produced at each speed. It can be seen that although the absolute hardness values differ by 1-2 kP in some cases (most likely due to differences in the two hardness testers used), the range of the window for the hardness values is comparable between the two machines. 

After scale-up into production, it was determined that an increase in moisture content would improve the formulation stability for a high dose wet granulated product. It was decided to use the Presster to predict the results that would be obtained in production when the moisture content of the final blend was increased. Blends with three moisture levels were compressed at two forces. As shown in Figure 5, as moisture content increases, tablet hardness increased. The dissolution profiles for the tablets with different moisture levels were compared and found to be within specification, indicating that raising the moisture content in the final blend should result in acceptable tablets in production. 

From the granulating screw (5) the granulated product is fed to an ejector, whence it is transferred by the air flow created by a fan to a cycline separator (6), in which the granulated material is separated from the dust-air mixture. The dust is passed to the filters and the granules are fed to a spiral oscillating conveyer (cooler) (7). 

Figure 3 Typical process flow—granulated product.

Figure 5 Cause-and-effect diagram (granulated product). 

Fig. 2.80. Drying time as a function of a peri- Layer thickness 1,20 mm 2, 12 mm 3, 8 mm odic, thorough mixing of a granulated product. 4, 5 mm. (Figure 12 from [2.17]).

---