User:Andbrew.downes/Sandbox.Grain bulk handling

=Grain Bulk Handling= In previous times grain was packed in bags for transport and storage and this needed lots of manual labour, the process requires equipment and manpower whenever the grain needs to be moved. http://en.wikipedia.org/wiki/Break_bulk_cargo

The change to bulk handling since the 1960's has enabled larger tonnages of grain to be transported and stored with fewer losses and using skilled operators and fewer labourers.

Horizontal grain transfer
Belt conveyor

Chain and flight conveyor 0.1 to 0.6 m/s

Chain and flight conveyors are used for horizontal and low incline grain transfer in silo elevator and mill galleries. Conveyors may be reversible so to transport products in both directions.

Screw conveyor

Vertical grain transfer
Bucket elevators

Pneumatic conveyors

Magnets
Magnetic separation used to remove magnetic metals from the grain to prevent sparks that might trigger a dust explosion. For this reason they are normally placed as close to the start of the bulk handling system as possible. Some plants have magnets before each bucket elevator.

There are two main types of magnetic separators:
 * Rotating magnets - that are self cleaning.
 * Permanent magnets

De-stoners
De-stoners use a strong updraught of air to create a fluidised bed and the vibrating screens separate the more dense stones from the lighter grain.

On the top deck most of the grain flows down the screens, while the the more dense grains and the stones are transferred to the lower deck where the lighter grains move downwards and the more dense stones are knocked upwards.

The key process parameters for the correct functioning of this machine are:
 * sufficient airflow through the screens to create a fluidised grain bed,
 * the angle of the screens,
 * the length of the stroke
 * the grain feed rate (in tons per hour).