#granulation technology

Granule physical attributes—bulk density, porosity, compressibility—are not fixed by the formulation alone. Drying method, rate, and endpoint temperature all influence how granule structure develops during moisture removal. When that structure is not engineered deliberately at the lab stage, downstream tablet performance becomes difficult to reproduce.

A lab scale fluid bed dryer gives formulators direct control over the thermal and mechanical conditions under which granule structure is finalized.

Granule Structure Is Decided During Drying, Not Granulation

In a development program for a modified-release tablet, a formulation team using a tray oven during early drying produced granules with adequate initial hardness. When transferred to a fluid bed processor at pilot scale, dissolution profiles shifted—extended release behavior was compromised. Investigation traced the change to granule porosity differences caused by the shift from static to fluidized drying.

Static drying allows surface crust formation before internal moisture escapes, creating a denser granule shell. Fluidized drying removes moisture more uniformly, producing a more porous granule matrix. For matrix-controlled release, this difference directly affects drug diffusion rates.

A lab scale fluid bed dryer eliminates this ambiguity at the point of development. Granule porosity, tapped density, and compressibility index can be established under fluidized conditions, allowing the formulation team to optimize binder concentration and wet massing time based on realistic granule structure.

Coating Performance Depends on What the Fluid Bed Processor Produces

Functional film coating—enteric, sustained release, taste masking—requires granule surfaces that accept polymer deposition uniformly. Surface rugosity and moisture content at coating entry are the two most controllable variables.

A lab scale fluid bed dryer with integrated coating capability, configured as a fluid bed processor, allows back-to-back drying and coating in the same bowl. Granules enter the coating phase at a defined and reproducible moisture state, eliminating inter-step moisture drift when granules are unloaded and transferred before coating.

Procurement teams evaluating lab drying equipment separately from coating equipment often create a workflow gap. A single fluid bed processor at lab scale handles both operations and generates unified process records—a clear advantage during tech transfer and deviation investigations.

What the Rapid Dryer Cannot Replicate

A rapid dryer removes moisture but does not reproduce the surface renewal mechanism inherent in fluidization. Granule surfaces remain largely static relative to the airstream, limiting heat and mass transfer to diffusion-dominated mechanisms—producing a different internal moisture gradient compared to fluidized drying.

For formulators working with hygroscopic actives, this difference can affect recrystallization behavior. A lab scale fluid bed dryer preserves the surface dynamics that govern moisture removal in production equipment, keeping development data relevant beyond the bench.

VJ Instruments builds lab scale fluid bed dryers with interchangeable process inserts, enabling top-spray granulation, Wurster coating, and rotor pelletization within a single unit—reducing capital expenditure without sacrificing process range.

FAQs

How does fluidized drying affect granule porosity compared to tray drying?

Fluidized drying removes moisture more uniformly, producing higher porosity. Tray drying promotes surface crust formation and denser shells. This difference directly impacts compressibility and dissolution behavior.

Why does granule moisture at coating entry matter?

High residual moisture causes polymer film instability and uneven coating distribution. Low moisture increases static charge and agglomeration risk. A defined moisture range at entry is essential for functional film performance.

Can a fluid bed processor replace both a dryer and a coating pan at lab scale?

Yes. With appropriate inserts, it handles wet granulation, drying, and coating sequentially in one bowl—reducing inter-step handling and process variability.

What granule attributes should be characterized after lab-scale fluid bed drying?

What are the main aspects of granulation process in organic fertilizer production line?

The first is the crushing process of organic fertilizer manufacturing machine. The raw materials should be crushed one day after fermentation. The fermented organic fertilizer can be dried, crushed and screened.

Then mix and mix. In the production process of a series of organic fertilizers, we can add inorganic nutrients and minerals according to different soil conditions and different crops, concentrate organic fertilizers and trace elements, and make the fertilizer contain a variety of nutrients required for plant growth, such as nitrogen, phosphorus, potassium, sodium, manganese, zinc, copper, etc

Next is granulation. According to the formula, nitrogen, phosphorus, potassium and fermentation products are mixed by computer, and then transported to the disc granulator for granulation. 

The formulas of organic and inorganic raw materials are mixed according to different series of products and fully mixed in the mixer. The granulation process of organic fertilizer is a crucial step.

Then let it cool and finally pack it.

The production process of organic fertilizer granulator mainly has the above aspects. According to the above overview, we can understand the whole process of organic fertilizer production.

Roller granulator is an important equipment for producing organic fertilizer. It plays a very important role in the organic fertilizer production industry. In our usual production activities, there are many methods of organic fertilizer granulator. In order to help you know more about the pelletizing process of organic fertilizer, let's focus on the roller pelletizer.

The model is a series of extrusion roller granulator sx. Its working principle is that the belt and pulley are driven by the motor, transmitted to the drive shaft through the reducer, and synchronized with the driven shaft through the transfer gear, and work in the opposite direction. The material is added from the hopper, formed by the hopper, demoulded and pelleted, and then transported to the crushing and screening chamber through a pair of chains, where the finished particles (balls) are screened and separated, and then returned to the material and mixed with the new material. Granulation. Through the continuous rotation of the motor and the continuous entry of materials, mass production can be realized. It can be adjusted by hydraulic pressure. The equipment not only has scientific and reasonable structure, but also has less investment, quick effect and good economic benefit.

Suitable raw materials for fertilizer roller extrusion granulator:

1) Ammonium sulfate, ammonium chloride, ammonium sulfate, etc 2) Potash fertilizer: potassium sulfate, plant ash, etc 3) Phosphate fertilizer: Superphosphate, superphosphate, calcium magnesium phosphate, phosphate rock powder, etc. The extrusion granulator of organic fertilizer should prevent the granular powder material from entering the extrusion granulator, and then use external force to compact the powder material tightly. Due to the use of different external force methods, the molecules recombine, making the material look like cylindrical particles. The whole process of forming and extruding is mechanical operation, which does not need manual operation. Stirring and granulation are mainly used to shape the material into a round shape.

More types of granulation method, go to https://fertilizergranulatorfactory.com/granulation-technology/

Advantages of roller extruder granulator:

Extrusion granulation method needs less equipment and less investment. In 1987, the International Center for fertilizer development (NFDC) conducted a study in developing countries The investment of extrusion granulation is only 50% of that of slurry granulation or chemical granulation, 20% less than that of steam granulation;

2. Extrusion granulation does not need heating and humidification of materials, which saves investment and energy consumption, and can be used for granulation of materials containing heat sensitive materials (such as ammonium bicarbonate and some organic substances);

3. There is no waste water or waste gas discharged outdoors in the production process, which will not pollute the environment;

4. The extrusion granulation process is short, easy to operate, easy to realize automatic production control and improve the production efficiency;

5. There are no special requirements for the properties and particle size distribution of raw materials. The sources of raw materials are wider and the production is more flexible. If the product plan needs to be changed, it will be more convenient and conducive to small batch production of special fertilizers;

6. The product has uniform particle size distribution, high hardness, no segregation and agglomeration.

The thickness of the large sheet produced by the extruding organic fertilizer granulator equipment is 5-20 mm, and the surface density is 1.5-3 times of the feed. Then the large flakes are made into flakes, crushed and sieved to obtain the desired granular product. 

The compound fertilizer extruder adopts screw, two rolling, two-way mold and two roll granulation, but it is essentially different from other granulating equipment. The granulator makes organic materials reach continuous, high speed and high strength in the granulation area. Rolling and shearing promote the physical granulation pressure between powder and granular material.

The production process of organic fertilizer adopts this method, the granulation effect is 2-3 times of that of traditional extruder, and the energy consumption is reduced by more than 60%.

Characteristics of NPK compound fertilizer extrusion granulating equipment: The double roller granulator frequency conversion PID operation feed automatic control system ensures the high power and stability of the granulation system. It can be widely used in sugar plant filtration sludge, alcohol, starch, animal husbandry and other enterprises, organic fertilizer, biological fertilizer, organic and inorganic compound fertilizer and other commercial granulation.