A belt conveyor system consists of an endless belt of resilient material connected between two flat pulleys and moved by rotating one of the pulleys by electric motor. Normally material is fed on the belt near the other end pulley. The moving belt carrying the material towards the driver pulley is likely to sag between the two end pulleys due to its self weight and pay load. That is why the belt is supported both on the carrying side and the return side by a number of rollers, called the idlers. As the belt is always under tension, it is prone to elongation resulting in slackness over the pulleys and loss of tension and power. That is why some kind of device for tensioning the belt is incorporated in the system. This tensioning device is known as take up arrangement. The system is inherently very simple.
Belt conveyors have attained a dominant position in transporting bulk materials due to a number of inherent advantages like the economy and safety of operation, reliability and practically numerous processing functions while supporting a continuous flow of material between operations. Low labour and low energy requirements are fundamental with belt conveyors as compared with other means of transportation. The reliability of belt conveyors has been proved over decades and in every industry. Belt conveyors are environmentally more acceptable than other means of transport. They neither neither pollutes the air nor deafens the ears. Conveying of a wide variety of materials is possible with belt conveyor, and belt conveyors are capable of transporting at a hourly rate much in excess of any practical requirement. Belt conveyors can deliver materials at a great distance from the loading point covering all odd terrain.
Essential components of a belt conveyor:
Belt conveyors consists of a driving pulley at the head end, and take up pulley at the tail end, both being accommodated in a steel frame. An endless belt connects the two pulleys on both runs and supported by suitable roller type supports, called the idlers. At the upper side of the conveyor also called the carrying side, because the pay load is carried on this side, the belt is supported by idler. At the other side also called the return side because usually there is no pay load, the belt is supported by idlers. In some designs the belt is supported by a stationery runway instead of idlers. In some special installations both the upper and lower sides transport loads (usually unit load) simultaneously in opposite directions. The driving pulley receives its rotation from drive unit.
The material to be conveyed is loaded on the belt by one or more feed hoppers mounted over the conveyor belt line normally placed at the tail end side. The load conveyed by the moving belt is discharged over the driving pulley into discharge spout. However discharge can be arranged at any point along the conveying run by means of special discharge devices. At the tail end side a device called the take up arrangement is attached with the take up pulley to keep the belt under a minimum tension so that the belt does not slip over the pulleys due to extension of its length. Belt cleaner removes material adhering to the outer belt face. It is usually located near the driving pulley.
Application of belt conveyor:
Belt conveyors are employed to convey a great variety of bulk materials and also unit loads along a horizontal or gently inclined paths. Such duties can be performed within the factory shed or in outdoor work. Within the factory shed belt conveyors are also employed to carry articles of light weight in line production from one operation to another. Belt conveyors are used to mechanize material handling operations in foundries to distribute moulding sand, mould cores and cast articles. Belt conveyors are used for carrying coal, ores, and minerals in power plants, mining industries, and metallurgical process plants. For handling food grains and building materials belt conveyors are frequently employed.
Capacities of a belt conveyor system may range from 500 to 5000 m3 / Hr. and more. The distance covered for a belt conveyor system may be as small as 50m (for indoor work) to 5 Km for supplying raw material from mine area.