This document provides information about various types of granulation equipment used in tablet production. It begins by defining granulation as a process of bonding particles together to improve flowability and compressibility. It then describes high-shear granulators, including their components and working. It discusses vertical and horizontal high-shear granulators. It also covers other low-shear granulation equipment like planetary mixers, sigma blade mixers, and fluidized bed granulators. The document concludes by discussing dry granulation methods like slugging and roller compaction, as well as melt granulation using extruders.
2. GRANULATION
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Granulation is the process of collecting particles together by creating
bonds between them.
Bonds are formed by compression or by using a binding agent.
Thus, the overall purpose of granulation is to improve the flowability
and compressibility of the powder mixture.
3. HIGH-SHEAR GRANULATORS
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Principle: Shear
Construction:
It consist of a mixing bowl, a three-bladed impeller, and an auxiliary
chopper.
A. Mixing bowl
Shape – cylindrical or conical
It can be jacketed for heating or cooling the contents in the bowl.
B. Impellers
Function:To mix the dry powder and spread the granulating fluid.
Rotation speed: 100 to 500 rpm range.
C. Chopper
Function:To break down the wet mass to produce granules.
Rotation speed: 1000 to 3000 rpm range.
4. Types of high shear granulator
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There are two types of HSG, based on the orientation and the position of the
impeller:
A. Vertical HSG
It could be either a top-driven or a bottom-driven unit.
Examples: ULTIMAGRAL™/ULTIMAPRO™
GMA™ Top driven
GMX™ vertical HSG
Glatt mixer/granulator
Pharma Matrix ™ Bottom driven
PMA600 Podium vertical HSG
Diosna P150
A. Horizontal HSG
Example: Littleford lodige mixer/granulator
Littleford MGT mixer/granulator
5. Working of high shear granulator
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Wet Granulation
This includes the following steps:
Loading all the ingredients into the mixing bowl.
Mixing of dry ingredients such as API, filler, and disintegrant, at high impeller and
chopper speeds for a short period of time (2–5min).
Addition of a liquid binder (either binder solution or solvent) into the powder
mixture, while both the impeller and the chopper are running at a low speed.
Wet massing with both the impeller and the chopper running at a high speed.
Removal of the resulting wet granules from the granulator bowl, and drying them
using an appropriate drying technique such as fluid-bed or tray drying.
Sieving the dried granules.
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Advantages:
Applicable to almost all kind of formulations.
Granulation process requires less binder.
Within short span granulation can be achieved.
The effect of over granulation can be reduced by milling.
Granulation of highly cohesive materials containing hydrophilic polymers, which is not
achievable with low-shear granulation processes.
Production of less friable and reproducible granules with a uniform particle size
distribution.
7. Disadvantages:
Over wetting of granules can lead to formation of large lumps.
Not suitable to thermolabile materials due to increase in temperature.
Production of less compressible granules, compared to low-shear granulation
processes
It has narrow range of operating conditions.
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8. Fig. 1:Top driven vertical high shear
granulator
Fig. 2: Bottom driven vertical high shear
granulator
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9. Littleford Loding mixer
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First high shear powder blender capable of rapidly pharmaceutical powder
and wet massing.
The equipment may also capable of producing agglomerated granular
particles that are ready for fluid bed or other drying methods.
Time: 30-60 sec.
Temperature rise: 10-150ºc
Fig. 3:
Littleford
loding
granulator
10. Diosna granulator
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Diosna mixer are as follow:
Give more normal PSD with lesser
fines.
Mixing time: 2 min
Granulation time: 8 min or less
Discharge time: 1min
Fig. 4: Diosna granulator
11. Low Shear Granulator
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These granulators generate less shear than granulators such as
extruders or the high-shear mechanical granulators.
These are also called as mechanical agitator granulator.
It involves ;
(1) Planetary mixers
(2) Orbiting screw mixers
(3) Sigma blade mixers.
12. Planetary Mixer/GRANULATOR
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The planetary motion of a planetary mixer when used as a granulator.
Different commercial names: Hobrat granulator, kitchen Aide granulator etc.
All of these mixers have the same basic makeup, which includes:
(a) Planetary motion
(b) Removable bowl, and
(c) Top-drive agitators.
13. Principle: Mechanism of mixing is shear. Shear is applied between moving blade
and stationary wall. Mixing arm moves around its own axis and around the central axis
so that it reaches every spot of the vessel.The plates in the blades are sloped so that
powder makes an upward movement to achieve tumbling action also.
Construction:
Consists of vertical cylinder shell which can be removed.
The blade is mounted from the top of the bowl.
Mixing shaft is driven by planetary gear and it is normally built with variable speed
drive.
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14. Working:
Material is loaded in the vessel.
Paddle is rotated at a slow speed.
The small clearance between the mixing vessel and paddle provides a kneading and
shearing action which ensures mixing of the material.
Intermittent scrapping also required to ensure perfect and uniform mixing.
Planetary mixer tend to be better of mixing drying powders in a horizontal plane
than in a vertical plane and so may require a distinct dry blending step prior to wet
granulation.
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15. Advantages:
Speed of rotation can be varied at will.
More useful for wet granulation process.
Disadvantages:
Mechanical heat is buildup within the powder mix.
It requires high power.
It has limited size and is useful for batch work only.
Uses:
Break down agglomerates rapidly.
Low speeds are used for dry blending and fast for wet granulation.
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17. Sigma blade mixer
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Principle: Shear.
Construction andWorking:
It consists of double tough shaped stationary bowl.
Two sigma shaped blades are fitted horizontally in each tough of the bowl.
These blades are connected to a fixed speed drive.
Mixer is loaded from top and unloaded by tilting the entire bowl.
The blades move at different speeds , one about twice than the other, which allows
movement of powder from sides to centers.
18. The material also moves top to downwards and gets sheared between the blades
and the wall of the tough resulting cascading action.
Perforated blades can be used to break lumps and aggregates which creates high
shear forces.
The final stage of mix represents an equilibrium state.
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Fig.9: Sigma blade granulator
19. Advantages:
It creates a minimum dead space during mixing.
It has close tolerances between the blades and the sidewalls as well as bottom of the
mixer shell.
Disadvantages:
Sigma blade mixer works at a fixed speed.
Uses:
Used in the wet granulation process in the manufacture of tablets, pill masses and
ointments.
It is primarily used for liquid – solid mixing, although it can be used for solid – solid
mixing.
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20. Fluidized Bed Granulator
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It is a multi-purpose equipment in that mixing, granulation and
drying are all carried out in the same equipment.
Granulation in a fluidized bed granulator is achieved by
suspending the powder in the air of the fluidized bed and then
spraying the binder solution from nozzles that are either
positioned above or below the powder bed depending on the type
of the granulator.
Fluidized bed granulator normally operates in a bubbling bed
regime.
21. Principle
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The powder is fluidized by the hot air in fluid bed granulator.
The binding liquid such as solution ,suspension is sprayed on the fluidized
powder to build liquid bridges among them to form agglomerates.
The liquid bridge that serve to hold the particle together in two ways:
1) By surface tension at the air liquid interface
2) By hydrostatic suction
• The liquid bridges are dried by the hot fluid air to stick the powder together.
• While the liquid sprayed continuously, the particles grow bigger to a desire
granule size.
The process is carried out continuously.
• Finally it forms uniform porous granules.
Fig.10: Mechanism of granules formation in FBG
22. construction
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The granulator is made of stainless steel or plastic.
It consist of hollow vertical chamber where dry, heated air enters
through the bottom of chamber and exhaust air exists through the
top of the chamber.
A detachable bowl is placed at the bottom of the dryer, which is
used for charging and discharging.
The bowl has a perforated bottom with a wire mesh support for
placing materials to be dried.
A fan is mounted in the upper part for circulating hot air.
Fresh air inlet, prefilter and heat exchanger are connected serially
to heat the air to the required temperatures.
The temperature of hot air and exit are monitored.
Bag filters are placed above the drying bowl for recovery of fines.
24. working
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A suction fan mounted at the top portion generates the airflow necessary for
fluidization of powders.
The air used for fluidization is heated to the desired temperature by an air
heater.
The liquid granulating agent is pumped from its container & sprayed as a fine
mist through a spray head onto the fluidized powder.
The wetted particles undergo agglomeration through particle contacts.
After appropriate agglomeration is achieved, the spray operation is discontinued
and the material is dried and discharged from unit.
25. Types Of Fluidized Bed Granulator
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Based on types of spray system, fluidized bed granulator are classified as:
1. Top spray FBG
2. Bottom spray FBG
3. Tangential spray FBG
Fig.12: spray
patterns in
FBG
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Advantages:
Easy to control Rapid mixing, uniform temperature and concentrations.
Resists rapid temperature changes, hence responds slowly to changes in operating
conditions.
Applicable for large or small scale operations.
Continuous operation.
Ease of process control due to stable conditions.
Heat transfer in fluidized bed granulator is 2-6 times greater than that generated by
tray dryer.
The process can be automated once parameters are optimized.
Drying occurs uniformly and the process prevents mottling.
27. Disadvantages:
Particle comminution (breakup) is common.
Pipe and vessel walls erode due to collisions by particles.
Non-uniform flow patterns (difficult to predict).
Size and type of particles, which can be handled by this technique, are limited.
Due to the complexity of fluidized bed behavior, there are often difficulties in
attempting to scale-up from smaller scale to industrial units.
Fluidized bed granulator is expensive to acquire.
There is tendency of filter clocking, demising, electrostatic charge and solvent
explosion is high.
It also produces low-density granules.
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28. Equipments in dry granulation
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A. Slugging (Old Method):
Material to be granulized is first made into a large compressed mass or "slug" typically
by way of a tablet press using large flat-faced tooling.
Disadvantages of Slugging:
Single batch processing
Frequent maintenance changeover
Poor process control
Poor economies of scale
low manufacturing output per hour
Excessive air and sound pollution
Increased use of storage containers
More energy and time required to produce 1 Kg of slugs than 1 Kg of roller compact.
30. Roller compactor/chilsonator
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Material particles are consolidated and densified by passing the material
between two high-pressure rollers.
Densified material from a roller compactor is then reduced to a uniform
granule size by milling.
capable of handling a large amount of material in a short period of
time
Invented by Francis Xavier Chilson.
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The compaction force of the roller compactor is controlled by three
variable:
1. The hydraulic pressure exerted on the compaction roller,
2. The rotational speed of the compaction rolls,
3. The rotational speed of the feed screws.
Advantages:
Increased production capacity
Greater control of compaction pressure
Dwell time and no need for excessive
lubrication of the powder.
33. Melt Granulation
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Melt granulation is a process in which the binder solution of the standard wet
granulation process is replaced with a meltable binder such as a wax or
polyethylene glycol (PEG), which is generally added in solid form, and melted
during the process by adding the necessary energy.
The most common production technique for melt granulation uses extruders
and spheronizers.
34. extruder
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Extrusion is method of applying pressure to a mass until it flows
through an orifice or defined opening.
Most common method for making multi particulate dosage forms.
Involves following steps:
Dry powder mix
Wet granulation
Extrusion through an extruder
Spheronization
Drying
35. Types of extruder
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1.Axial extruder: A screw extruder where material is extruded in the same
direction as it being transported by screws.
Fig.17:Axial screw extruder
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2. Dome extruder: A screw extruder with dome shaped extrusion area.
3.
Radial extruder: A screw extruder where material is extruded radially to the
direction as it is being transported by screws.
Fig.18: Dome extruder
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4. Basket extruder: Extruder using oscillating or circular blades to wipe material
through a perforated screen.
Fig.19: Radial extruder Fig.20: Basket extruder