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From powder to granules: What is the mysterious process of wet granulation?
In today's chemical and pharmaceutical industries, the granulation process plays a vital role. Granulation is the process of forming powdered or solid materials into particles, which typically range in size from 0.2 to 4.0 millimeters. This also makes granulation technology indispensable in many technical processes, especially in the process of making pills and granules.
One of the primary functions of granulation is to prevent the ingredients of a powder mixture from stratifying, which is caused by differences in size or density of different substances.
The core of granulation is to aggregate one or more powder particles into granules and allows the manufacture of tablets to proceed within the desired range. This process is accomplished through compression or the use of adhesives that create chemical bonds between particles. As a result, the pharmaceutical industry has long relied on this technology to ensure particle stability, predictability and reproducibility.
During the powder granulation process, powder characteristics such as size, shape and surface characteristics will directly affect the flow and compression properties of the final product. For example, granulated sugar is easier to compress into tablets than powdered sugar because the tiny particles of powdered sugar have poor flow and compression properties.
The process of wet granulation
Wet granulation is the process of forming particles by adding a granulating liquid to a powder bed. This process usually requires a high-shear granulator, a twin-screw granulator or a fluidized bed granulator. When the granulating liquid comes into contact with the powder constituent materials, liquid bridges are formed causing the main powder particles to aggregate into wet particles.
Wet granulation liquids are usually composed of volatile and non-toxic solvents, typical liquids such as water, ethanol, isopropyl alcohol, etc. These solutions are easy to handle and safe for personnel.
The liquid used comes from the characteristics of the powder, and the saturated state of the liquid will affect the properties of the particles. Under different humidity states, including wet state, capillary state and trumpet state, the presence of liquid helps the particles to adhere. In this process, polymer adhesives are also key components, such as polyvinylpyrrolidone (PVP), which can help form a strong bond during the drying process.
Dry granulation technology
Dry granulation is another granulation method that does not use liquid and is particularly suitable for materials that are sensitive to moisture and heat. In this process, powder particles are aggregated and compressed under high pressure. Commonly used equipment includes swing pellet mills and roller compactors.
In this process, the powder particles are compressed by a pressure device to form a continuous strip of material or small particles, which are then ground and mixed.
Granulation technology is also of great significance in plastic recycling and fertilizer production. In plastic recycling, the pelletization process cuts plastic items into small pellets and forms flakes or pellets that can be reused in subsequent plastic extrusions. In the processing of fertilizers, granular products are more economical, easy to transport and store, and convenient for application.
Overall, granulation technology not only improves the handling of materials, but also affects the competitiveness of the final product in the market.
The change from powder to granules undoubtedly makes us think about the development potential and challenges of this process in the future pharmaceutical and other industries. With the advancement of science and technology, can the granulation process more efficiently adapt to environmental protection needs and develop more innovative technologies?
