The document outlines different types of materials handling equipment, focusing on conveyors. It discusses bucket conveyors, screw conveyors, and pneumatic conveyors. For each type, it describes the basic components and operation, advantages and disadvantages, applications, and variations. Bucket conveyors use buckets to transport bulk materials vertically. Screw conveyors use rotating screws to move materials horizontally or at an incline. Pneumatic conveyors transport powdered or granular materials through pipes using air pressure differences.

1. MATERIALS HANDLING EQUIPMENT
Lecture Six
Conveyors
Outlines
 Bucket conveyors
 Screw conveyors
 Pneumatic conveyors
By: Amanuel D.
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2. 4. Bucket conveyors
• Bucket conveyors consist of endless chains or belts to which
are attached buckets to convey bulk material in horizontal,
inclined, and vertical paths.
• The buckets remain in carrying position until they are tipped to
discharge the material. Various discharging mechanisms are
available.
• is a mechanism for transportation flow able bulk materials
vertically.
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3. Cont..
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4. Cont..
Advantage of bucket elevators
Bucket elevator offers number of advantages. Here are some,
• They can elevate in all type of weather conditions
• They can carry the free flow material or material with poor
flow characteristics
• Wide range of lifting (Buckets are available in different
shapes and sizes and hence can be varied as per your
requirements)
• Large conveying capacity
• High hoisting height
• Less maintenance and long service life
• Low driving power
• Stable and reliable running
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5. Cont..
Disadvantage of bucket elevators
– Initial cost is high
– The lifting capacity is limited to about 30m
– Inclination is limited to 60 degree with horizontal
– Transfer capacity: 60 tons/hr
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6. Bucket conveyor applications
Bucket Elevators are easy to use and that’s why they are so much
popular, especially in processing industry and for bulk material
handling. Here are the common applications of Bucket Elevators,
• Mining Industries
• Construction Projects
• Large Oil Mills
• Other Processing Industries and many more
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7. Types of bucket Conveyors
Bucket elevators are classified based on bucket spacing and mode
of discharge (loading and unloading) of materials, there are three
types of bucket conveyors.
(i) Centrifugal discharge elevators:
 The buckets are spaced at a regular pitch to avoid
interference in loading and discharging.
 The materials are discharged by centrifugal action as the
buckets pass over the head wheel.
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8. Cont..
(ii) Positive discharge elevators:
 These are similar to centrifugal discharge type excepting
that the buckets are side-mounted on two strands of
chains (i.e.buckets lie between two strands of chains),
 and are provided with a pair of two slight sprockets under
the head sprockets to invert the buckets for complete
discharge.
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9. Cont..
(iii) Continuous discharge elevators :
In these elevators, V-type buckets are used without any gap
between them.
These elevators are employed for handling larger lumps and
materials that may be difficult to handle by centrifugal
discharge.
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10. 5. Screw conveyors
• A screw conveyor is a mechanism that uses a rotating
helical screw blade, called a "flighting", usually within a tube, to
move liquid or granular materials.
• The screws may operate inside tubes or U-shaped troughs,
supported every few feet by suspended bearings around which
the material flows.
• They are used in many bulk handling industries.
• Screw conveyors in modern industry are often used horizontally
or at a slight incline as an efficient way to move semi-solid
materials, including food waste, wood chips,
aggregates, cereal grains, animal feed, boiler ash, meat and
bone meal, municipal solid waste, and many others.
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11. Cont..
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13. Cont..
• To suit the screw rotation and the desired direction of material
travel, there are different types of screw used in screw conveyor.
a. Helical spiral
b. Ribbon spiral
c. Paddle-flight;
d. Cut-flight
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14. Cont..
Advantage of Screw conveyors
– Cheap initial cost
– Simple and compact
– Dust tight
– Operated at positive as well as negative pressure
– Material can be conveyed horizontally as well as vertically
– Most suitable for short distance.
Disadvantage:
– High power consumption
– Length is limited up to 30m
– High maintenance due to high wear and tear.
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15. Typical applications of Screw conveyors
Screw conveyors serve a wide variety of purpose in many industries.
Some of the application areas are:
1. When the materials are extremely hot
2. If the materials are sticky or viscous
3. When extremely abrasive materials are to be conveyed
4. When the materials are corrosive.
5. When the materials are to be mixed
6. If materials are to be heated or cooled, which conveying they
may required jacketed troughs arranged for circulating
heating or cooling media.
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16. 6. Pneumatic conveyors
• Pneumatic conveyors is a method of transporting bulk materials in
the form of powder, short fiber and granules over a pipeline as a
mixture with air or due to pressure of air.
• The material is conveyed in an enclosed tube system by means
of compressed air.
• The pneumatic conveyor systems uses differential air pressure to
efficiently move materials from one point to the other.
• Since air flows from high to low pressure, its application at one
end of the pipe will move bulk materials to the other end.
• Thus any pneumatic conveyor consists of an air supply equipment
(blower or compressor), pipelines, product storages, air lock feeders
and dust filters.
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17. Cont..
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18. Cont..
There are three basic system used in pneumatic conveyors to
generate high-velocity air stream are:
1. Suction or Vacuum system
• utilizing a vacuum or negative pressure created in the
pipeline to draw the material with the surrounding air .
• The system operated at a low pressure, which is practically
0.4–0.5 atm below atmosphere, and
• is utilized mainly in conveying light free flowing materials
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19. Cont..
2. Pressure type system
• In which a positive pressure is used to push material from
one point to the next.
• The system is ideal for conveying material from one
loading point to a number of unloading points.
• It operates at a pressure of 6 atm and upwards.
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20. Cont..
3. Combination system (push – pull system)
– In which a suction system is used to convey material from
a number of loading points and
– A pressure system is employed to deliver it to a number of
unloading points.
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21. Cont..
Merits of Pneumatic Conveying
These systems have superior advantages as compared to mechanical
material handling systems.
– High effectiveness
– High durability and reliability
– Simple design
– High adaptability to harsh environment
– Safety
– Easy selection of speed and pressure
– Gives more flexibility than mechanical conveyors
– Occupy less space
– Totally enclosed
– Low maintenance
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22. The limitations of pneumatic system
– Relatively low accuracy
– Low loading
– Processing required before use
– Uneven moving speed
– Noise
– High power requirement
– Large dust collection system
– Cannot be used for:
• Large particle
• High bulk density materials
• Sticky materials
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23. Pneumatic conveyor component
A pneumatic conveyor transporting bulk materials in a stream of air
consists of the following device.
1. Intake units
• One of the most delicate problems in pneumatic conveyors is the
introduction of material to the flow of air at a regulated rate.
• There are different methods some of them are
a) Nozzle injector
– The increased velocity due to the nozzle pushes the material
into the pipe od pneumatic conveyor.
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24. Cont..
b) Rotating valve
– This is used for non-abrasive materials and a capacity less
than 15ton/hr and of conveying length 100 to 200m.
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25. Cont..
C) Stationary screw feed
– This is widely applied for cement and other powdered
materials.
– The material from the hopper is forced by high
– Speed motor drive screw through feed funnel into a mixing
chamber.
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26. Cont..
d) Suction Nozzle
– They are used to charge material into the pipe of suction
conveyors.
– They used negative pressure to pickup (suck) material by
mixing them with air.
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27. Cont..
2. Conveying pipe and change over values
• Steam less steel pipes ranging in diameter from 50 to 250mm are
used in high conveyors.
• Lighter pipes with a wall thickness of 1 to 3 mm may be used in
medium and low pressure conveyors.
• The pipes are joined with standard flanges, correspondingly
sealed.
• A changeover values serves to connect the pumping unit to one
of the branches of the pipe.
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3) Separators and dust collectors
• The material – loaded air enters the separator where the loss of
velocity, change of direction of the flux and the action of the
centrifugal force separate the material from the air stream.
• The cross – sectional area of the separator is 50 to 150 times
larger than that of the conveying pipe.
• The velocity falls as low as 0.2 to 0.8m/s which is low enough
to clean the conveying air stream even of small particles.
• The separators clean the conveying air stream even of
small particles and the dust where collect in one place
using dust collectors.
By: Amanuel Diriba

29. Cont..
Applications in the Industries
• Both dilute and dense phase conveying systems find applications in
many industries.
• Powder or particulate materials are easily moved using this
method.
• They are applied in moving construction materials such as cement
and sand; minerals such as alumina, lime, gypsum, salt, fluorspar;
powder handling equipment's; bag house dust collection systems
and raw cement during manufacture in clinker.
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