Conveyors: power-driven – Conveyor having impinging fluid to feed – shift or discharge... – Having cleaning means
Patent
1993-05-12
1995-08-15
Dayoan, D. Glenn
Conveyors: power-driven
Conveyor having impinging fluid to feed, shift or discharge...
Having cleaning means
198561, B65G 4731
Patent
active
054411440
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
The present invention relates to spillage from conveyor belts such as are used to convey coal or like material such as mineral ores and other particulates. In particular, the present invention discloses a method and apparatus for reducing spillage of the conveyed material from such conveyor belts.
BACKGROUND ART
Conventional conveyor belts comprise an endless loop of conveyor belt which passes over various rollers. Despite various drive roller, head roller and tail roller configurations the belt essentially consists of two runs which are positioned one above the other and extend between a source location and a destination location. In operation the belt travels in opposite directions on the two runs.
The coal, iron ore, bauxite or similar mineral or other particulate material is loaded onto the upper surface of the upper run at the source location and is discharged from this material conveying surface at the destination location. On the lower (return) run, the material conveying surface forms the lower surface.
The conveyed material which is not discharged at the designation location continues with the belt and is termed "carry over". This carry over material which adheres to the belt, often despite the actions of a scraper blade positioned to scrape the material carrying surface of the belt at the destination location, is subject to all the vibration which the belt on the return run experiences. Accordingly, this carry over material is dislodged from the lower surface of the belt during the return run and falls downwardly to the floor of the mine, or working surface of the stockpiling operation.
Such spillage represents a substantial volume, up to 2%, of the total material conveyed. Accordingly, it is not unknown for the depth of such spillage to reach, and even exceed, the height of idler rollers over which the return run of the belt moves. A substantial cost of any such mining or conveying operation is the cost of removing such belt spillage. In a typical Australian underground coal mine utilising longwall mining techniques, approximately 2 million tonnes (tons) are produced each year. The conveyor line to convey this material often consists of eight individual conveyors with a total transport distance from coal face to stock pile of approximately 8 kms (5 miles). It is not unknown for the cost of returning the spillage to the upper surface of the upper run of the conveyor belt to cost more than the spilled material is worth.
In an effort to reduce the volume of carry over material, the material carrying surface of the conveyor belt is normally scraped. Such scrapers fall into two distinct categories. One category is the light scraper which uses a wire, rubber blade, or similar relatively flexible scraper which is intended primarily to dislodge any loose material from the belt surface. The other category of scraper is a hard scraper having a blade of tungsten carbide, or similar. Although such hard scrapers reduce the volume of carry over material, they also substantially contribute to belt wear, by up to 30% under normal operating conditions. In the event of some malfunction, the hard scraper can tear or rip a belt to an extent that it has to be replaced.
In addition to the above mentioned problems of loss of yield, the cost of cleaning up, and the wear of the belt caused by hard scrapers; the problem of carry back and subsequent belt spillage produces other undesirable side effects. In particular, with coal the presence of fine coal dust on the floor of the mine constitutes a substantial fire hazard. In addition to the belt being progressively buried by carry back material, the carry back material also interferes with the operation of rollers, tail tensioners, and other standard items of conveyor apparatus since the material is continually being showered in fine particulate and generally abrasive material.
The carry back of fine particulate material on the return run of conveyors is a much greater problem to present day conveyor operators than in years past. There are two basic
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patent: 2007874 (1935-07-01), Redler
patent: 2375697 (1945-05-01), Sinden
patent: 4068755 (1978-01-01), Parkes et al.
patent: 4366628 (1983-01-01), George
patent: 4921089 (1990-05-01), Teske
Barnett Investments Pty Limited
Dayoan D. Glenn
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