Types of Bucket Elevators

What is a Bucket Elevator?

A bucket elevator, is a mechanism for transfer of flowable bulk materials vertically.

Bucket elevators are designed to move flowing powders or bulk solids vertically. Bucket elevators use an endless belt or chain and have a series of buckets attached to it. Bulk material is fed into an inlet hopper. Buckets (or cups) dig into the material and convey it up and over the head sprocket/pulley, and then throw the material out a discharge chute or throat.

It consists of:

1. Buckets to contain the material
2. A belt or chain to carry the buckets and transmit the pull
3. Electric Motor and Gear Box to drive the belt
4. Accessories for loading the buckets or picking up the material, for receiving the discharged material, for maintaining the belt tension and for enclosing and protecting the elevator.

Bucket elevators are not self-feeding, and are fed at a controlled rate. The buckets are usually where the chain or belt path is vertical or steeply inclined in a single plane. The buckets are returned back down to a tail pulley or sprocket at the bottom.

There are four broad classifications of bucket elevators: centrifugal, continuous, positive, and internal discharge. The most commonly used are the centrifugal and continuous discharge elevators.

Centrifugal Elevators

Centrifugal bucket elevators are most commonly used to convey all free-flowing, powdered bulk solids such as grains, animal feed, sand, minerals, sugar, aggregates, chemicals, etc. They operate at high speeds, which throw the materials out the buckets into discharge throats by centrifugal force. Centrifugal Discharge Bucket Elevator can have buckets mounted at intervals on chain or belt. Centrifugal Discharge Bucket Elevators are used to handle bulk materials which can be picked up by the spaced buckets as they pass under the boot wheel and discharge by centrifugal forces as the buckets pass over the head.

A centrifugal discharge elevator may be vertical or inclined. Vertical elevators depend entirely on the action of centrifugal force to get the material into the discharge chute and must be run at speeds relatively high. Inclined elevators with buckets spaced apart or set close together may have the discharge chute set partly under the head pulley. Since they don’t depend entirely on the centrifugal force to put the material into the chute, the speed may be relatively lower.

Continuous Elevators

Continuous bucket elevators are used to handle friable, fragile materials because they minimize product damage or are used to handle light fluffy materials where aeration of the product must be avoided. Continuous bucket elevators may be used to handle the same kinds of material as the centrifugal type, however they are recommended especially for handling materials that are difficult to pick up in a boot or friable materials. Continuousbucket elevators have buckets spaced continuously on chain or belt and operate at slower speeds. The continuous bucket placement allows the force of gravity to discharge their load onto the inverted front of the proceeding bucket. The bucket then guides that material into the discharge throat on the descending side of the elevator.