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1. MIXING
3rd Year
)

2. Definition
Definition
It is a process in which two or more substances in a separate
condition or roughly separate condition are treated in such way so
that components of one ingredient will stay near components of
other ingredients.
It is considered the most widely used pharmaceutical manufacturing
process.
It is difficult to find a pharmaceutical product in which mixing is not
done at one stage or the other during its manufacturing.
2

3. Purposes of Mixing
1. To produce simple physical mixture e.g. two powders of same
color are mixed or two powders of different colors are mixed.
2. To produce physical changes. E.g. dissolution (solid to liquid),
adding solid powder to semisolid ointment (solid to semi solid).
3. To produce dispersion e.g. suspension, emulsion
4. To promote chemical reactions e.g. mixing of catalyst to
reactant
5. Potency reduction (e.g. dilution) ---------
6. Potency increment (e.g. synergistic mixture)
7. To measure correct doses
8. To increase stability e.g. antioxidant
9. To increase palatability e. g. sweeting agents, coloring agents
3

4. Application of Mixing
A. Liquid mixing:
1. Solution-
1. To increase uniformity e.g sugar syrup (crystal growth)
2. To promote mass transfer
2. Emulsion-
1. To disperse immiscible liquid
2. To increase uniformity
3. To promote mass transfer
4. To obtain uniform dose
5. To disperse emulsifying agent
3. Suspension
1. To disperse solid drugs
2. To increase uniformity
3. To promote mass transfer
4. To obtain uniform dose
5. To disperse suspanding agent
4

5. Application of Mixing
B. Solid mixing:
1. Powder-
1. To increase uniformity e.g sugar
2. To promote mass transfer
2. Tablet-
1. To mix two or more drugs
2. To increase uniformity
3. To promote mass transfer
4. To add granulating agents/coloring agent/binder/diluting/disintegrating agent
3. Capsule
1. To mix two or more drugs
2. To increase uniformity
3. To promote mass transfer
4. To mix diluting/disintegrating agents
5

6. Application of Mixing
C. Semisolid mixing:
1. Cream, ointment, paste-
1. Mixing ingredients e.g two or more drugs
2. To increase uniformity
3. To promote mass transfer
4. To produce soothing effect.
D. Aerosol:
1. To increase uniformity
2. To increase stability
6

7. Classification of mixing
A. Mixing of solids
B. Mixing of liquids
C. Mixing of solid to liquid (suspension)
D. Mixing of immiscible liquids (emulsion)
E. Mixing of solid to semisolids
7
1. Based on ingredient to be mixed

8. Classification of mixing
A. Batch mixer
A. Impeller
B. Air jets
C. Fluid jets
B. Continuous mixer
A. Triple roller mixer
B. Baffeled pipe mixer
C. Mixing chamber with flow induced circulation.
8
2. Based on pattern of mixing

9. 3. Mixtures may be classified based on energy
requirement as follows:
a. Positive mixtures
b. Negative mixtures
c. Neutral mixtures

10. 1. Positive mixtures
 These types of mixtures are formed
when two or more than two gases or miscible
liquids are mixed together by means of
diffusion process. In this case no energy is
required provided the time allowed for
solution formation is sufficient. These types of
materials do not create any problem in
mixing.

11. 2. Negative mixtures
These types of mixtures are formed when insoluble
solids are mixed with a vehicle to form a suspension or
when two immiscible liquids are mixed to form an
emulsion. These mixtures are more difficult to prepare
and require a higher degree of mixing with external
force as there is tendency of the components of these
mixtures separate out unless they are continuously
stirred.

12. 3. Neutral Mixtures
 Many pharmaceutical products such
as pastes, ointments and mixed powders
are the examples of neutral mixtures.
They are static in their behavior. The
components of such products do not have
any tendency to mix spontaneously but
once mixed, they do not separate out
easily.

13. A. Mixing of solids
• In the manufacture of tablets or granules normally a number of additives
are added. Therefore mixing of powder becomes essential part of the
process.
• Mixing is considered as a critical factor, especially in case of potent
drugs and low dose drugs where high amounts of adjuvants are added.
• The diverse characteristics of particles such as size, shape, volume,
surface area density, porosity, and flow charge affects the solid mixing.
• Depending on their flow properties solids are divided into two classes
as cohesive and non cohesive.
13

14. Interparticle interactions & segregation
Inertial forces:
These forces hold neighboring particles in fixed relative position.
E.g.: Vander Waal forces, electrostatic forces, surface forces.
Surface forces:
Cohesive forces and frictional forces results through surface-surface
interactions which resist the movement of particles, hence they should be
minimal.
During mixing, through surface forces a charge is develop on surface which
produce particle-particle repulsions, which make random mixing impossible.
These depend on surface area, surface roughness, polarity, charge, moisture.
14

15. Segregation
• Poor flow properties.
• Particle size difference.
• Difference in mobilities.
• Differences in particle density and shape.
• Long transporting stage.
• Dusting/abrasion stage.
 It may occur even after mixing.
15
causes:
During mixing operation one type of material when separated from other type
of material because of gravitational force or repulsive force, the phenomenon
is known as segregation.

16. Mechanism of mixing of solids
1. Convective mixing/Macro mixing:
Inversion of the powder bed using blades or paddles or screw element, in
which large mass of material moves from one place to another.
2. Shear mixing:
In this type, forces of attraction are broken down so that each particle
moves on its own between regions of different components and parallel to
their surface. This usually happen through the use of slipper bed.
3. Diffusion mixing/Micro mixing:
Involves the random motion of particle within the powder bed, thereby
particles change their position relative to one another. This due to the
concentration difference of different particles.
16

17. Mixing process - steps
• In the solid-solid mixing operations , four steps are involves.
These are:
1. Expansion of the bed of solids
2. Application of 3-dimensional shear forces to the powder bed.
3. Mix long enough to permit true randomization of particles.
4. Maintain randomization.
17

18. Degree of mixing
1. Ideal mixing or perfect mixing:
2. Acceptable mixing: 2 types
A. Random mixing
B. Coating mixing
18

19. Factors influencing mixing
• State of aggregation
• State of segregation
• Nature of the surface
• Density of the particles
• Particle size
• Particle shape
• Particle charge
• Proportion of materials
• Friability
• Presence of moisture
• Time of mixing 19

20. EQUIPMENT
Criteria:
1. Powder bed should not be filled for more than 60%
2. Particles should be subjected to movement in three
directions
3. Shearing force should be sufficient to prevent
aggregation.
4. There should be no centrifugal effect
5. Forces should not cause breakage of the particles.
6. The mixing process should be stopped abruptly.
20

21. Classification of equipment for solid mixing
• Based on flow properties:
1.Mixer for free flowing solids:
e.g.: V cone blend , Double cone blender
2.Mixer for cohesive solids:
e.g.: Sigma blender, Planetary mixer
• Based on scale of mixing:
1.Batch type (small scale) mixer:
e.g.: Mortar and pestle, V cone blender, Double cone blender,
Ribbon blender, Sigma blender, Planetary paddle
2.Continuous type (large scale) mixer:
e.g.: barrel type, zigzag type
21

22. Classification of equipment for solid mixing
• Based on movement of mixing chanber:
1.Moving mixing chamber mixer:
e.g.: V cone blend , Double cone blender
2.Stationary mixing chamber mixer:
e.g.: Ribbon mixer
22

23. Twin shell blender or V cone blender
• It is V shaped and made up of stainless
steel or transparent plastic.
23

24. Twin shell blender or V cone blender
24
strand
shaft
• It is V shaped and made up of stainless steel or transparent plastic.

25. Twin shell blender or V cone blender

26. Twin shell blender or V cone blender

27. Twin shell blender or V cone blender

28. Twin shell blender or V cone blender
Operation:
• Material is loaded through shell hatches and
emptying is normally done through an apex
port.
• The material is loaded approximately 50-
60% of the total volume.
• Small models – 20 kg , rotate at 35rpm
• Large models – 1 ton, rotate at 15rpm
• As the blender rotates , the material
undergoes tumbling motion.
• When V is inverted, the material splits into
two portions. This process of dividing and
recombining continuously yields ordered
mixing by mechanical means.

29. Double cone blender
• It consists of double cone on rotating shaft.
• It is operated using a motor connected to
the shaft.
• Motor, double cone drum and shaft are
suspended above platform using stand.
• Material is loaded and emptying is done
through the same port.
Double cone
blender 29

30. Double cone blender
Operation:
• The rate of rotation should be optimum
depending upon the size, shape of the
tumbler and nature of the material to be
mixed.
• The rate of rotation commonly ranges from
30-100rpm.
• Mixing occurs due to tumbling motion.
Double cone
blender 30

31. Advantages of V cone blender and double cone blenders:
• If fragile granules are to be blended, twin shell blender is suitable
because of minimum attrition.
• They handle large capacities.
• Easy to clean , load, and unload.
• This equipment requires minimum maintenance.
• Economic
• May be baffled and unbaffled
Disadvantages of V cone blender and double cone blenders:
• Twin shell blender needs high headspace for installation.
• It is not suitable for fine particulate system or ingredients of large
differences in the particle size distribution, because not enough shear is
applied.
• If powders are free flowing, serial dilution is required for the addition
of low dose active ingredients.
31

32. Drum Mixer
Angularly positioned
drum mixer 32
Horizontally positioned
drum mixer

33. Tumbling blenders with agitator mixing
blades (Baffles)
33

34. Advantages of Drum mixer:
• Baffles are useful for both wet and dry mixing.
• Wide range of shearing force can be applied with agitator bars permitting
the intimate mixing of very fine as well as coarse powders.
• Simple apparatus.
• Economic mixer
Disadvantages of Drum mixer :
• Attrition is large, size reduction of friable particles results.
• Cleaning may be a problem,
34

35. Ribbon blender
DESIGN
Consists of U-shaped horizontal cylindrical vessel
usually open at the top.
It is fitted with two helical blades, which are
mounted on the same shaft through the long axis of
the trough.
Blades have both right and left hand twists.
It can be loaded by top loading.
The material is discharged through one or more
discharge valves located at the bottom most
point of the vessel.. 35

36. Ribbon blender
OPERATION:
MECHANISM OF MIXING:
Ribbon blenders operate on the two principle of mixing: convection and
diffusion.
Convective mixing is the macro movement of large portions of the solids.
Convection mixing occurs when the solids are turned using helical blades
horizontal axis of the agitator assembly.
The other type of ribbon mixing is diffusion mixing which is the micro mixing
that occurs when individual particles are moved relative to the surrounding
particles. In the ribbon blender diffusion occurs when the particles in front of
the ribbon are moved in one direction while nearby partials are not moved or
lag behind.
36

37. Working:
Uses:
 Used for mixing of finely divided solids, wet solid mass, and
plastic solids.
 Uniform size and density materials can be easily mixed.
 Used for solid – solid and liquid – solid mixing.
37

38. Advantages of ribbon blender:
• High shear can be applied by using perforated baffles,
which bring about a rubbing and breakdown of
aggregates.
• Headroom requires less space.
• Wet solid and plastic solid material can be mixed.
Disadvantages of ribbon blender:
• It is a poor mixer, because movement of particles is
two dimensional.
• Shearing action is less than in planetary mixer.
• It has fixed speed drive.
38

39. Sigma blade mixer
DESIGN
It consists of double tough shaped stationary
bowl. There is an opening between the two bowls.
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 or by bottom discharge valve.
Two blade in each tough are arranged in such way,
so that movement of one blade lead materials
from center to the sidewall of the vessel and
movement of other blade lead materials from near
the sidewall of the vessel to other tough.
Sigma blade mixer 39

40. Sigma blade mixer
40

41. Sigma blade mixer
OPERATION
In operation, material is loaded through the top of the container to typically
40 to 65 percent of the mixer’s total volumetric capacity.
The rotation of the blades is through heavy duty drive systems typically
consisting of a motor, and gears.
Mixing may be carried out at ambient temperature or under controlled
temperature conditions. The mixer troughs can be provided with jackets for
circulation of hot or cold media to maintain the required temperature
conditions within the mixer.
The discharge of the material from the mixer container is either by tilting of
the mixer container, bottom discharge valve, or through an extruder.The
mixer may be equipped with any one of these discharge arrangements.

42. Uses of sigma blade mixer:
• 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.
• Adhesive materials, rubber materials, chewing gum, food and
confectionary materials can be easily mixed using sigma blade
mixer
42

43. Advantages of sigma blade mixer:
• It can be used for wet solid and rubber like materials which are
difficult to mix by other solid mixer
• Sigma blade mixer require a minimum dead space during
mixing.
Disadvantages of sigma blade mixer:
• Sigma blade mixer works at a fixed speed.
• More expensive than drum mixer, double cone blender etc.
43

44. Zigzag continuous blender
• Material undergoes tumbling
motion.
• It is rotating shell type having
several V shaped blenders
connected in series.
• When V section is inverted the
material splits into two portions ;
one half moves backward while
another half moves forward.
• As the first V section clears the
charge, a fresh feed enters, hence
used for continuous blending.
• It consists of a long shell, which takes the shape of several V shaped blenders connected in
series.
• At one end of the shell a chamber for feeding hopper is attached.
• The other end allows the discharge of material through a discharge outlet.
• The shell is inclined towards to discharge end.
Zigzag continuous blender
44

45. Advantages of zigzag continuous blenders:
• It is a continuous type mixer.
• They handle large capacities.
• Easy to load, and unload.
Disadvantages of zigzag continuous blenders :
• Twin shell blender needs high headspace for installation.
• Some times difficult to clean.
• Expensive than batch type mixer.
45

46. Muller mixer
46
Design:
plow
plow

47. 47
Principle:
Muller mixer consist of two heavy wheels that mix solid or rubber or paste
materials by rubbing over inner wall of the mixing chamber similar to mortar
and pestle.
Operation:
Advantages:
1. Heavy solid, paste and rubber like materials can be mix.
2. By adjusting wheel and mixing chamber batch size can be adjusted easily.
Disadvantages:
1. Need heavy duty motor.
2. Maintenance cost is high
3. Not so efficient, so prolonged mixing time is required.

48. 48
Double Muller mixer
Advantages:
1. Heavy solid, paste and rubber like materials can be mix.
2. By adjusting wheel and mixing chamber batch size can be adjusted easily.
3. Efficient, so mixing time is less
Disadvantages:
1. Need heavy duty motor.
2. Maintenance cost is high

49. 49
Twin rotor mixer
Design:
It consist of two shafts where paddles or cylindrical screws are attached. Two
shafts are rotating in opposite direction. The space between shafts can be
adjusted based on materials to be mix. Shaft speed ranging low to moderate.
Application:
It is normally uses for continuous mixing
of free flowing solids.
Often little amount of liquid is added to prevent attrition of product.

50. 50

51. B. Mixing of Fluids
Mechanism:
• Bulk transport: Movement of large portion of a material from one location
to another location in a give system. Rotating blades and paddles are used.
• Turbulent mixing: Highly effective, mixing is due to turbulent flow which
results in random fluctuation of the fluid velocity at any given point within
the system. Fluid velocity at a given point changes in 3 directions (X, Y and
Z).
• Laminar mixing: Laminar mixing processes are based on the repeated
separation of the flow into layers, followed by redistribution and
recombination parallel to the flow direction.
• Molecular diffusion: Mixing at molecular level in which one types of
molecules among others.
51

52. Mixing Apparatus for fluids
• A Container and
• A Mixing Device or
impeller
• Baffle
• Shaft
• Motor
52

53. 53

54. Mixing Device
• Based on shape and pitch , the are classified into 3
types,
»Propellers
»Turbines
»Paddles
54

55. Propellers
• It consists of number of blades, generally 3 bladed
design is most common for liquids. Blades may be
right or left handed depending upon the slant of their
blades.
• Two are more propellers are used for deep tank.
• Size of propeller is small and may increased up to 0.5
metres depending upon the size of the tank.
• Small size propellers can rotate up to 8000rpm and
produce longitudinal movement.
55

56. 56

57. Advantages of propellers:
Used when high mixing capacity is required.
Effective for thin liquids which have maximum viscosity of 2.0
pascals.sec or slurry up to 10% solids of fine mesh size.
Effective gas-liquid dispersion is possible at laboratory scale.
Disadvantages of propellers:
Propellers are not normally effective with liquids of viscosity greater
than 5pascal.second, such as glycerin castor oil, etc.,
57

58. Turbines
• A turbine consists of a circular disc to which
a number of short blades are attached.
• Blades may be straight or curved.
• The diameter of the turbine ranges from 30-
50% of the diameter of the vessel.
• Turbines rotates at a lower speed than the
propellers (50-200rpm).
• Flat blade turbines produce radial and
tangential flow but as the speed increases
radial flow dominates.
• Pitched blade turbine produces axial flow.
• Near the impeller zone of rapid currents, high
turbulence and intense shear is observed.
58

59. 59
Pitched blade turbine

60. Advantages of Turbines:
• Turbines give greater shearing forces than
propellers through the rpm rate is less.
Therefore suitable for emulsification.
• Effective for high viscous solutions with a
wide range of viscosities up to 7.0 Pascal.
Second.
• In low viscous materials of large volumes, turbine create a strong currents
which spread throughout the tank destroying stagnant pockets.
• They can handle slurries with 60% solids.
• Turbines are suitable for liquids of large volume and high viscosity, if the tank
is baffled.
60

61. Paddles
• A paddle consists of a central hub with
long flat blades attached to it vertically.
• Two blades or four blades are common.
sometimes the blades are pitched and
may be dished or hemispherical in shape
and have a large surface area in relation
to the tank in which they are used.
• Paddles rotates at a low speed of
100rpm.
• They push the liquid radially and no axial action unless blades are pitched.
• In deep tanks several paddles are attached one above the other on the same shaft.
• At very low speeds it gives mild agitation in unbaffled tank but as for high speeds
baffles are necessary.
61

62. Uses of paddles:
Paddles are used in the
manufacture of viscous liquids
such as antacid suspensions, agar
and pectin related purgatives,
antidiarrheal mixtures such as
bismuth-kaolin.
Advantages of paddles:
Vortex formation is not possible with paddle
impellers because of low speed mixing.
Disadvantages of paddles:
For efficient mixing baffled tanks are required.
62

63. Flow pattern during mixing
1. Tangential component or
circular path:
Acts in the direction tangent to the circle of
rotation around the impeller shaft. If shaft is placed
vertically and centrally, tangential flow follows a
circular path around the shaft and creates a vortex in
the liquid.
2.Radial component:
Act in the direction towards the wall
of the container. Excessive radial
flow takes the material to the
container wall then material falls to
the bottom and rotate as the mass
beneath the impeller
63

64. 3. Axial component or longitudinal or
vertical: Acts in the direction parallel to the impeller shaft.
Inadequate longitudinal component causes the liquid and solid to rotate
in layers without mixing. Adequate longitudinal pattern is best used to
generate strong vertical currents particularly when suspending solids are
present in a liquid.
Impeller type Flow component
Propellers Axial
Turbines Axial or tangential or both
Paddles Radial and tangential
Paddles with pitch Radial, tangential and axial 64

65. Vortex formation
• A strong circulatory flow pattern sometimes
manifests into formation of a vortex near the
impeller shaft.
Vortex can be formed when-
• Shaft is placed symmetrically in the tank.
• Blades in the turbines are arranged
perpendicular to the central shaft.
• At high impeller speeds
• In unbaffled tanks
65

66. Disadvantages of vortex formation
• Vortex formation reduces mixing efficiency by
reducing velocity of the impeller relative to the
surrounding fluid.
• When vortex reaches the impeller, air from the
surface of the liquid are drawn and air bubbles
are produced.
• Air bubbles in the fluid can create uneven
loading of the impeller blades.
• Entrapped air causes oxidation of the
substances in certain cases.
• Overflow of liquid from the mixing container.
66

67. Prevention of vortex formation
1. Impeller should in any one of the position that can avoid symmetry such as
off central, inclined, side entering, etc., and should be deep in the liquid.
2. Baffled containers should be used. In such case impeller can be mounted
vertically at the center.
67

68. Return flow with Draft tubes
Uses:
• Draft tubes are fitted to equipment used in the manufacture of certain emulsions.
• When solid particles tend to float on the surface of the liquid, they are dispersed
using draft tubes.
Disadvantage:
• Draft tubes add to the fluid friction in the system.
• These reduce rate of flow.
• Draft tubes are used to control the
direction and velocity of the flow
around the impeller.
• These are mounted around the
propeller. In case of turbines, draft
tubes are mounted immediately
above the impeller.
68

69. Factors influencing mixing of liquids in tanks
 Material related factors-
– Properties of liquids: physical properties of materials to be mixed.
e.g.: Density, Viscosity
 Equipment related factors-
– Shape of impeller: Propeller type, straight, vertical, curved, or pitched.
– Position of impeller: Central, off-center, side entry, vertical or inclined etc.,
– Shape and size of the container: cylindrical or other geometric forms.
– Presence or absence of baffles..
 Process related factors-
– Speed of rotation of the impeller.
– Time required for mixing.
– Batch size.
69

70. Other Equipment for Liquid
mixing
1. Air jet mixer
2. Jet mixer
3. Flow mixer or line mixer or pipe mixer
70

71. Air jet mixer
• Design:
-Air inlet
-Top filter
-Product outlet
-Mixing vessel
-Nozzles (to control flow of air)
-Air exhaust
71
• Principle: It is a batch type mixer,
where mixing of solid to liquid or
liquid to liquid is carried out by
passing high speed air that fluidized
mixing materials.
Top filter
Air exhaust

72. Air jet mixer
• When compressed air jets are passed
from the bottom of a vessel, air bubbles
are formed in the liquid phase.
• The suplying high pressure air
makes high speed vortex flux flow at
the bottom of vessel by special
designed nozzles. Therefore, the
solids are fluidezed as like a "tornado",
and return to this center of this vortex
flow repeatly.
•So, these agglomarated fine particles
are dispersed by centrifugal force.
72

73. 2. Jet mixer
• It consists of a vessel and a mixing device
known as Jet.
• An individual jet has two concentric
nozzles with a suction chamber between
them.
• Two liquids are introduced into the mixing
tank at different velocities.
• One liquid is pumped through a small
nozzle at uniform high velocity.
• The fast moving liquid impinges on slow
moving liquid at high velocity.
73

74. C. Mixing of immiscible Liquids
Carried mainly in the manufacture of emulsions, and the
equipment used for the preparation of an emulsion is known as emulsifier. Also
known as homogenizer as it results in fine emulsion.
Fine emulsion is prepared in 2 stages.
In 1st stage coarse emulsion is prepared by using one of the following
process:-
– Mechanical blender
– Hand homogenizer
– Porcelain mortar and pestle
– Milk shake mixer
– Propeller in a baffled tank
the 2nd stage to get fine emulsion by using following process:-
– Silverson emulsifier
– Colloidal mill
– Rapisonic homogenizer
74

75. Equipment
• Silverson emulsifier
• Colloidal mill
• Rapisonic homogenizer
75

76. Mixing of immiscible Liquids
Silverson mixer -Emulsifier
• It produces intense shearing forces and turbulence by use of
high speed rotors.
• Circulation of material induced mechanically by emulsifier
head. Head carries turbine blades
• Circulation of the material ensures rapid breakdown of the
dispersed liquid into smaller globules.
• It consists of long supporting columns and a central portion.
Central portion consists of a shaft which is connected to
motor at one end and other to the head.
• Turbine blades are surrounded by a mesh, which is further
enclosed by a cover having openings.
76

77. 77

78. Uses:
• Used for the preparation of emulsions and creams
of fine particle size.
Advantages:
• Silver son mixer is available in different sizes to
handle the liquids ranging from a few milliliters
to several thousand liters.
• Can be used for batch operations as well as for
continuous operations by incorporating into a
pipeline, through which the immiscible liquids
flow.
• Disadvantages:
• Occasionally, there is a chance is clogging of
pores of the mesh.
78

79. 79
Paste Mixer
Classification:
A. According to arrangement of equipment-
1. Change can mixer
e.g. change can mixer with planetary motion
2. Stationary can mixer
e.g. Anchor mixer, gate mixer
B. According to Mode of operation-
1. Batch mixer
e.g. Bambury mixer
2. Continuous mixer
e.g. twin screw continuous mixer

80. 80
Anchor Mixer
Because of special shape of impeller as anchor, it is known as anchor mixer.
This is heavy duty impeller used for mixing viscous liquid.
Power: 1-500 HP
Design:
-Impeller is anchor shaped and possess grilled
blade. Blades are flat, which are arranged in
impeller with enough gap between them through
which liquid can pass.
-Shaft
-Motor
-mixing chamber
Principle:
Operation:
Advantage: viscous/paste can be mix, vortex formation is low.
Disadvantage: rpm is low (15-45), high energy motor is required, more time consuming,
side mixing is not efficient.

81. 81
Gate Mixer

82. 82
Change Can Mixer

83. 83
Change Can Mixer
Classification:
A. According to arrangement of equipment-
1. Simple change can mixer
2. Change can mixer with planetary motion
3. Change can mixer with rotating turntable

84. 84
Change Can Mixer
Design:
-Change an mixer is a verticle batch
type mixer, where container is a
separate unit placed on the platform
-Impeller or agitator is made up of
three angularly fixed blades
connected by a frame to flateform via
a motor, and wheel.
-Wheel allow the agitator to move up
and down
-Mixing chamber can be equipped
with heating system using a jacket
type container wall through which
hot/cool water can be pass.
Operation: Materials to be mix is placed in the can. By using motor and wheel
agitator move upward and set the container on the frame. Then mixing carried out for
sufficient time. After mixing agitator move upward and container is removed. A
separate container containing a new batch to be mix is then placed for the operation.

85. 85
Change Can Mixer
Advantage:
1. Separate container allows the batch to be carefully measure the weight before and
after the mixing operation.
2. As mixer chamber can be remove from the mixer, so easy to clean.
3. Relatively inexpensive
4. During mixing materials in the mixing chamber can be monitored.
5. Heating or cooling system can be incorporated if necessary
Disadvantage:
1. Paste adjacent to the wall of container difficult to mix, some times long spatula needed
to lead the materials at active zone of the mixer.

86. 86
Change Can Mixer with planetary motion
It is a modified form of change can mixer where impeller blade rotate on its own axis as
well as impeller can move from one place to another place that allow efficient mixing of
materials adjacent to the wall of the container.

87. 87
Change Can Mixer with planetary motion
Advantage:
1. Separate container allows the batch to be carefully measure the weight before and
after the mixing operation.
2. As mixer chamber can be remove from the mixer, so easy to clean.
3. Paste adjacent to the wall of container difficult to mix, some times long spatula
needed to lead the materials at active zone of the mixer. Relatively inexpensive
4. During mixing materials of mixing chamber can be monitored.
5. Heating or cooling system can be incorporated if necessary
Disadvantage:
1. Relatively expensive

88. 88
Change Can Mixer with rotating turntable
It is a modified form of change can mixer where a rotating turntable is added on the frame
below the agitator. The motion of rotating turntable allow efficient mixing of materials
adjacent to the wall of the container.

89. 89
Advantage:
1. Separate container allows the batch to be carefully measure the weight before and
after the mixing operation.
2. As mixer chamber can be remove from the mixer, so easy to clean.
3. Paste adjacent to the wall of container difficult to mix, some times long spatula
needed to lead the materials at active zone of the mixer. Relatively inexpensive
4. During mixing materials of mixing chamber can be monitored.
5. Heating or cooling system can be incorporated if necessary
Disadvantage:
1. Relatively expensive
Change Can Mixer with rotating turntable

90. 90
Triple roller mixer / Roller mixer
1. Roller mills consisting one or more rollers, usually three rollers. All rollers have equal
diameter.
2. The space between roll and platform vary.
3. In case of roll adjacent to hopper have highest space between roll and platform. This
space is lowest between discharge roll and frame.
4. Rolls are moving at counter current motion (direction). Speed of receiving roll is
slowest and discharge roll rotate fastest.
5. There is a scrapper knife to cut product film.
Design:

91. 91
Triple roller mixer / Roller mixer
Materials to be mix is feed into mixer through hopper. Materials are allowed to mix for a
specific time. Mixed material is discharged from the mixer as thin film, which is cut using
scrapper knife.
Operation:

92. 92
Advantage:
1. Mixing efficiency is high.
2. Size reduction of materials is possible
Disadvantage:
1. Motor should be heavy duty to rotate rolls
2. Operation cost is high due to high power consumption.
Triple roller mixer / Roller mixer

93. 93
Bambury mixer
1. It is a heavy duty paste mixer consist of a large chamber, which is the combination of
two round chambers.
2. There is no partition between these two chamber.
3. Each chamber has a oval shape heavy weight blade (around 1000 pound wt) .
4. There is opening at the top to feed materials and an opening at the bottom to discharge
finished product
Design:

94. 94
1. Materials to be mix is feed into mixer through the top opening. Heavy weight blade
usually rotate at 20-50 rpm.
2. Rotor blade rotate at opposite direction that lead movement of materials from one
chamber to another.
3. After sufficient mixing materials are discharged through the bottom opening.
Operation:
Bambury mixer

95. 95
Advantage:
1. Mixing efficiency is high.
2. Mixing time is less around 10 minutes
3. Paste and rubber like materials can be mix.
Disadvantage:
1. Motor should be heavy duty to rotate rotor blade
2. Operation cost is high due to high power consumption.
3. Usually use for small batch materials.
Bambury mixer