What-are-the-different-types-of-granulation-technologies II
Writer： admin Time：2020-03-27 09:15 Browse：℃
1. One step fluidized-bed granulation or fluid bed drying granulation
1) What is one step fluidized-bed granulation?
Mixing materials and spraying adhesive in mist. Therefore, they can be granulated. Meanwhile, granules produced can be dried. These steps are continuous and finished in a single machine. Such a way is called fluidized-bed granulation, or fluid spraying granulation.
2) Advantage of one step fluidized-bed granulation
A single machine can be used to finish mixing, granulation, drying and even coating. This method features easy operation, time saving, low labor intensity, small granule size, uniform size distribution, good fluidity and compressibility but low granule intensity.
2. Spray drying granulation
1) What is spray drying granulation
Materials are firstly mixed with adhesive to produce medicine solution or suspension of about 50-60% solid. The solution or suspension is then sprayed by pump through high pressure spraying device. When they are sprayed into drying chamber, hot air in it will evaporate water so that dry fine ball granules can be produced directly.
2) Advantage of spry drying granulation
In this way, solid granules can be directly made from liquid. Mist droplets of large area, hot air of high temperature, quick drying, short heating time and relatively low temperature for dry materials, all of these factors enable this method to process heat-sensitive materials.
3) Shortages: high equipment cost, large energy consumption and high operation cost
Recently, spraying granulation has been widely applied in production of antibiotic powder injection and micro capsules, research on solid dispersion and drying of Chinese medicine extract.
3. Dry granulation or roller compaction
1) What is dry granulation?
After medicine powders are mixed (diluent can be added if necessary), appropriate machine can be used to directly lump the mixture and break it into granules of specific size. Compression force is used to generate binding force. Dry granulation can be classified into two types, namely, pressing and roller compacting.
2) Pressing: Pressing powders into tablets with diameter of 20-25mm on heavy tablet press and then crushing tablets into granules of appropriate size.
3) Roller compaction: Medicine powders are first rolled into tablets on roller compactor and then crushed into granules.
4) Advantage of roller compaction: It is always used for heat- or water-sensitive and compressible medicines. It is simple and labor and time saving. However, it should be noted that pressing might lead to crystal change and activity lowering.
4. Chinese medicine granulation
They are generally produced through wet granulation.
1) Fine medicine powder granulation: if the dosage of formula is not too large, medicines can be milled into fine powders of over 100 meshes. Then proper moisturizer or adhesive can be added to produce mixture, which is screened and granulated afterwards.
2) Mixing and granulation of thick medicine extract and fine medicine powders: Part medicines are made into thick extract and the others are milled into fine powders. They are then mixed, screened and dried. By doing so, adhesive can be displaced by thick extract to reduce tablet volume. If thick extract doesn’t obtain enough adhesion, some other adhesive can be added.
3) Dry extract granulation: Dry extract is extracted and made from all medicines (except medicines containing volatile ingredients) in the formula. It is then milled to granules. Or it can be milled to fine powders first and then appropriate moisturizer is added to produce mixture and at last granulate.
