Pellets
Pellet fuels (or pellets) are biofuels formed from compressed organic matter or biomass. Pellets can be produced from any one of five general categories of biomass: industrial waste and co-products, food trash, agricultural residues, energy crops, and virgin lumber.
Pellets offer many additional features associated with conventional tablets. OPPL is able to offer a comprehensive range of pelletization processes and help you to choose the procedure that best satisfies your needs.
Pelletization
Our pelletizing resolutions involve extrusion and spheronization, production by powder layering and liquid coating, and pelletization via melt and wet granulation.
Process & Product Development
Based on our strong commitment to process development, Pharmaceutical Technology Centres in Belgium, Denmark, Switzerland, UK, Singapore, China and USA provide global technological support and know-how to the life science industries. Our experienced staff can assist with process development, optimisation and transfer, and our state-of-the-art test and application centres can produce pharmaceutical dosage forms for clinical studies. Customers can also hire or lease equipment to perform in-house product development and process feasibility work.
Pelletizing Process Principles
Liquid layering of pellets: The multi-functional PRECISION-COATER™ and top spray coater systems can all be used to produce pellets by layering the active material onto an inert core. Non-pareil starter pellets are sprayed with a solution or suspension of the active material and dried simultaneously.
Powder layering of pellets: When the actual ingredient is in powder form, pelletization can be accomplished by spraying starter pellets including the active powder and, at the same time, a liquid binder solution. The layered pellets is then dried.
Melt granulation pelletization: Melt pelletization can be done using the PMA™ Pellet Processor or the ULTIMAPRO™ Single Pot Processor. The active and binder powders are mixed and heated to a temperature above the melting point of the binder. Granulation and pelletization are then completed in a single operation.
This is a very fast, truly one-pot process during which a heated jacket or optional microwave energy can be used to melt the powders. Special polymer liners are also available to minimize sticking. Applications include forming pellets from 0.5–2.0 mm in diameter at batch sizes up to 150 kg. By selecting an appropriate binder material, sustained release forms can be developed without additional coating.
Wet granulation pelletization: The active substance is combined with microcrystalline cellulose (5–30%) and the mixture is granulated with water or an organic solvent. During the process, the granules are compacted and spheronized. This operation can be performed using the PMA™ Pellet Processor or the ULTIMAPRO™.
Again, special polymer liners can be used to decrease sticking and specific impellers can be selected for optimal pellet quality. Extremely round pellets (0.5–2.0 mm in diameter) can be produced at batch capacities up to 150 kg.
Extrusion and spheronization: The NICA™ Pelletizing System is a turnkey pellet production plant that merges a mixer/granulator, extruder and spheronizer in a single, integrated process. Wet powders continuously move into a low-shear radial extruder; the extrusions are fragmented and formed into pellets within the spheronizer.
The process is fast, robust, continuous and easy to scale-up. Standalone units and fully integrated systems are available. Very high drug loads can be processed and integration with up- and downstream equipment is possible. Predictable pellet sizes of 0.5–3.0 mm can be achieved at capacities up to 300 kg/h.
Extrusion & Sphenronization
Extrusion / Spheronization is a regularly used manufacturing process in the pharmaceutical industry where small drug-containing spheres/pellets are made. The pellets produced in the spheronization process are then typically encapsulated. The steps required in the spheronization manufacturing process comprise dry blending, wet massing, extrusion, spheronization and drying/layering.
Screening may be performed to optimize the particle size distribution range prior to encapsulation.
The active and excipients are initially mixed together in a granulator followed by the addition of a granulation liquid. The resulting wet mass is passed over a screen forming soft, pliable extrudate. The size of the final pellets (spheres) is principally determined by the hole diameter of the screen used in the extrusion step.
The extrudate is loaded to the spheronizer that consists of a plate/disc, spinning about speeds of approximately 400–500 rpm, in the spheronization bowl. The extrudate is split down into cylindrical shaped pieces of approximately equal length, which is directly related to the diameter of the extrudate. These cylindrical segments are slowly rounded by the collisions with the bowl wall, the plate and each other. While the particles have reached the aspired level of sphericity, they are then discharged from the spheronizer. The wet pellets are collected and dried, typically, in a fluid bed drier (FBD). The FBD can also be used to coat the pellets if required.
Spheronization Process Challenges
Although spheronization is an approved manufacturing operation in the pharmaceutical industry, the actual composition of the pellets from the extrudate is not invariably fully understood for all manufacturing processes. Also the impact of raw material variability is not always fully understood and this variability may cause product quality issues. Uniform particle size distribution, good sphericity, shape and surface features, have been identified as critical to quality attributes (CQA) of pellets. These critical quality attributes are particularly important if the pellets are to be coated for controlled release purposes. Understanding how pellets are formed and the impact of raw material variability for each of your spheronization processes may be crucial to the success and consistency of your products. Therefore, measuring particle size distributions and particle shape can be critical to the success of your businesses