Screw conveyor

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First Grain Auger circa 1945

Screw conveyor

A screw conveyor or auger conveyor is a mechanism that uses a rotating helical screw blade, called a "flighting", usually within a tube, to move liquid or granular materials. 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.

History

The first type of screw conveyor was the Archimedes' screw, used since ancient times to pump irrigation water. Archimedes' screw consists of a screw (a helical surface surrounding a central cylindrical shaft) inside a hollow pipe. The screw is turned usually by a windmill or by manual labor. As the shaft turns, the bottom end scoops up a volume of water. This water is then pushed up the tube by the rotating helicoid until it pours out from the top of the tube.

Design and Function

Screw conveyors can be operated with the flow of material inclined upward. When space allows, this is a very economical method of elevating and conveying. As the angle of inclination increases, the capacity of a given unit rapidly decreases. The rotating part of the conveyor is sometimes called simply an auger.

Components

The main components of a screw conveyor include:

• Screw (Flighting): The helical blade that rotates to move the material.
• Trough: The housing that contains the screw.
• Drive Mechanism: The motor and gear system that powers the screw.
• End Bearings: Support the ends of the screw and allow it to rotate.

Applications

Screw conveyors are used in many industries, including:

• Agriculture: For handling grains, feed, and fertilizers.
• Food processing: For moving food products and waste.
• Mining: For transporting bulk materials like coal and ore.
• Wastewater treatment: For conveying sludge and other waste materials.

Advantages

• Simple and robust design.
• Can handle a wide variety of materials.
• Can be used to mix and blend materials.
• Can be used to control the flow of material.

Disadvantages

• Limited to relatively short distances.
• Can be prone to wear and tear.
• Not suitable for handling abrasive materials.

Related Pages

• Archimedes' screw
• Bulk material handling
• Conveyor system
• Material handling equipment