A bucket elevator is a conveyor for carrying bulk materials in a vertical or inclined path. Bucket elevators for the mechanical, vertical transportation of materials have become a crucial link in the production process in many industrial sectors.
Typical elevator consists of:
1. An endless belt,
2. A chain or chains, to which buckets are attached,
3. Necessary loading and discharging terminal machinery,
4. A drive arrangement,
5. Supporting frame or casing.
Material is fed into an inlet hopper. Buckets (or cups) dig into the material, and convey it up to and over the head sprocket/pulley, then throwing the material out the discharge throat. The emptied buckets then continue back down to the boot to continue the cycle.
Industrial Bucket Elevators are made in a variety of shapes, weights and sizes, utilizing centrifugal buckets or continuous buckets. The belt can be made of natural fibres, rubber, plastic or metal.
Centrifugal Bucket Elevators are most commonly used to convey free flowing materials. They operate at high speeds, which throw the materials out the buckets into discharge throat by centrifugal force.
Continuous Bucket Elevators have buckets spaced continuously and operate at slower speeds. The continuous bucket placement allows the force of gravity to discharge their load onto the inverted front of the preceding bucket. The bucket then guides that material into the discharge throat on the descending side of the elevator. They minimize product damage or are used to handle light, fluffy materials where aeration of the product must be avoided.
The motion of belt or chain is un-directional. Bucket elevator is a very simple yet reliable device for lifting of bulk materials. Bucket elevators enjoy a few advantages, which include simplicity of design and fabrication, requires minimum floor space, low initial investment.
Types of bucket elevators:
Often bucket elevators are classified according to the bucket spacing and mode of discharge. They are:
1. Centrifugal discharge elevators
2. Gravity or Continuous discharge elevators
3. Positive discharge elevators
Components of bucket elevators:
The essential components of a bucket elevator are:
2. Carrying medium
3. Boot arrangement
4. Head arrangement
Typical average materials which can be conveyed by bucket elevators are:
· Lime stone crushed to 25 to 30 mm size,
· Foundry sand,
· Animal feed
· Phosphate rock,
· Cement mill clinker
· Fragile materials
· Plastic Granules
Limitations of the system include the following points:
· Lump size should be under 100mm
· The material should not be very sticky
· The temperature of the materials should be ambient or slightly above
· The materials should not be excessively corrosive or abrasive
Advantages of belt system over chain system:
The traction element may be either endless belt or endless chain, but belt system is preferred under certain conditions for the following reasons:
· Higher speeds possible
· Quieter operation
· Possess better abrasive resistance to materials like sand, coke etc.