Dear Mr. LJAM,

Please mention the name of material, its bulk density and its lump density. The handling of lumps of 1500 mm by belt conveyor is a very exceptional situation. Whether the belt conveyor can deal with such lump depends upon the material. In case if you have material like lignite, one can look for the possibility of use. However if the material is like granite, the use of belt conveyor is ruled out.

Please also specify the shape of lumps i.e. expected width, length and depth for design considerations. It is understood that the 1500 mm you are referring is corner to corner largest dimensions and the maximum size lumps. Also mention the % of maximum lumps, along with average size gradation.

The material loading will require the special considerations and layout, if it is possible to handle.

Generally people put primary crusher immediately at the source of such material and reduce it to manageable size for handling by belt conveyor. This results into economical and standard way for handling such material.

The subject issue also depends upon the length of conveyor. Please mention the length of conveyor.

If the conveyor happens to be relatively short, and you have decided to handle it by belt conveyor then it is possible to have central roller of longer length.

My above information does not imply that I am agreeing to use belt conveyor for handling of lumps in your specific installation. My reply is only in context of the investigation.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Author of Book : Belt Feeder Design and Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25882916 ■

Hello LJAM

I have done such an installation before to handle 1800mm long lumps on a belt conveyor.

I am also currently involved with the design of a very wide heavy duty conveyor for huge lumps of iron ore

The secret is to load the belt correctly with the best possible chute configuration, and also use the correct idler configuration.

Don't even think of automatic belt tracking for this application.

For details of the idler configuration I have developed for this application you can send me an e-mail at gspriggs@global.co.za and I can reply directly.

(I would appreciate the duty requirements though, then I can help you properly)

Regards

LSL Tekpro ■

Dear Mr. LJAM,

We have alot of experience in the recycling business. There you also can have big lumps weighing 2.000 kgs.

My advise is to support the belt at the intake with a 20 mm thick plate and a steelplate for the rest of the belt too if th ebelt conveyor is not that long. For bigger lenght a combination of rollers and glide plates. In this case you will have no steering problems and will simple sensors and automatic steering rollers in the returm part be enough.

kind regards,

Jur Lommerts

Jansen & Heuning Bulk Handling Systems

e-mail: jfl@jh.nl

URL: www.jh.nl ■

Unfortunately we do not supply conveyor belt systems.

But if you need to install conveyor belt scrapers or need a dust suppression system, you are more than welcome to contact us.

Please refer to our website for further information (www.buwip.de)

Best regards

B+w GmbH ■

LJAM:

I agree with Graham Spriggs, that an automatic belt tracking system is not a good approach.

If large lumps are unavoidable, consider the use of a grizzly to absorb the impact and to place the lump centrally on the belt. (Trip wires, profile gates, light sensors, or other I/O device should be used to shut the system down if too big of a lump is passed to the belt. This will prevent belt or system damage.) In addition to a grizzly, design your chute so that good loading is achieved.

A major concern is the potential plugging of your load chute and grizzly, if so equipped, by oversized lumps. The answer to that concern is to prevent large lumps from getting to that point.

Regards, ■

Mr. LJAM,

I have had occasion to engineer and supply belt feeders for very severe applications, including direct loading, of blasted copper ore, by 240 ton end dump trucks and conveying the material to the mouth of a primary gyratory type crusher. Belt training is not the main worry.

The system must be designed on the one hand to minimize the impact at loading (by curved profile scallping grizzly and by special care in operational procedure) and on the other hand to absorb very high impact load since it will occur. The design included large live shaft rolls with very thick rubber lagging. These vary for severity of their location, being supported on spring suspensions at the loading area.

Joseph A. Dos Santos, PE ■

Dear LJAM

I believe the conveyor concept is feasisble and has been implemented before to handle 9.5 ton lump over 54m. There is one critical parameter you have not stated: conveyor capacity.

The belt should not run over 1 m/s similar to a belt feeder. A 6310 bearing series, with impact rubber covered rolls spaced at 1 meter centers, and belt sag control held to less than 1% need to be considered to keep the point loading within acceptable limits.

The idler transom must be engineered similar to a stockpile or under gyratory belt feeder. Past systems had the idler frame supported on a rubber shock absorber

The idlers can be designed with live shaft bearings, again similar to belt feeders if the physics didctates. The impact force on belt at the chute discharge and idlers along the length can be determined using discrete element modeling (DEM)

All speculation is meaningless unless the flow rate is known and the impact energy is controlled within reason.

There have been large rock belts designed to handle your specs as indicated by others. There are videos (movies) of their design and operation.

Chute design is the critical feature in your quest. ■