Feeders plugged

Posted in: , on 2. Apr. 2007 - 11:12


we currently have a problem with our feeders plugging off. for example we will run out of coal on a previous shift, we will leave about ten to twenty tons of raw coal on top of the three foot by three foot opening leading to the feeder. after we wash out the next day underground will dump anywhere from eight to twelve thousand tons on top of them. when we fire up later that day we start the feeders but we soon find out about three feet above the surface they bridgeover. currently we use a high pressure water hose to unbridge. this creates build up on our belt lines and other chutes to plugg off. we also have tried to put a bucket of coarse coal and or rock on top of them to prevent this occuring. ideas greatly appreciated. thanks

Re: Feeders Plugged

Posted on 3. Apr. 2007 - 05:57

Redesign the bin bottom. A 3x3 opening implies a poor design. The slot opening in the horizontal and vertical planes are not arranged according to your dimensions.

In addition, the internal wall geometry and wall liner surface is implied to be incorrect born from the same design as the opening .

It sounds like you need a good bin designer that also understands the belt/feeder aspect.

Lawrence Nordell Conveyor Dynamics, Inc. website, email & phone contacts: www.conveyor-dynamics.com nordell@conveyor-dynamics.com phone: USA 360-671-2200 fax: USA 360-671-8450

Feeder Type

Posted on 3. Apr. 2007 - 06:29

I assume these are Mechanical pan feeders or are they BELT feeders?

I agree with Nordell :

- the opening to me seems undersized

- the angle of repose of the sidewalls could be shallow

- If designed properly the problem should not exist

I assume these are belt feeders vs mechanical pan feeders?

Best Regards, George Baker Regional Sales Manager - Canada TELSMITH Inc Mequon, WI 1-519-242-6664 Cell E: (work) [email]gbaker@telsmith.com[/email] E: (home) [email] gggman353@gmail.com[/email] website: [url]www.telsmith.com[/url] Manufacturer of portable, modular and stationary mineral processing equipment for the aggregate and mining industries.

Feeder Drives

Posted on 3. Apr. 2007 - 06:30

Are they designed with adequate drives to handle the task?

Best Regards, George Baker Regional Sales Manager - Canada TELSMITH Inc Mequon, WI 1-519-242-6664 Cell E: (work) [email]gbaker@telsmith.com[/email] E: (home) [email] gggman353@gmail.com[/email] website: [url]www.telsmith.com[/url] Manufacturer of portable, modular and stationary mineral processing equipment for the aggregate and mining industries.

Re: Feeders Plugged

Posted on 3. Apr. 2007 - 11:45


You should have your material tested before you redesign your chutes and you'd be interested in Flow Function - instantaneous and after some time of storage, let say 3 days to take into account long weekends or maintenance break. It will tell you the relationship between Unconfined Yield Strenght and Major Consolidation Stress for the critical moisture content - the higher the stress the bigger bridge it will be able to support. You can try easy solutions first - line your hopper with ceramics or poly - it may help but you should have a chute designer to have a look into it.

Ziggy Gregory www.vibfem.com.au

Re: Feeders Plugged

Posted on 3. Apr. 2007 - 02:10

they are mechanical pan feeders. we have had the same set up for about fourteen years. but those fourteen years we ran seven days a week twenty four hours a day. we was only down for necessary repairs. but in recent months we have washed all of our stock pile and run out of coal on a weekly basis. before there was so much coal and so little down time that the feeders never bridged over. but now its a different story. thank you for everyones input.

the chute leading to the feeder is approx. 3x3x3 square chute in the ground. we have a reclaim tunnel where the feeders are. the chutes are in concrete about three feet thick. basically its a metal lined hole in the roof of the tunnel where they stuck a feeder under. i agree it is a very bad design. using the water hose to me seems a little dangerous when you six feet on a ladder sticking a water nozzel in the chute and opening the valve. you dont necessarly get hit with material but...your next to a bouncing feeder and a running belt line. i was just wondering if there was anything we could do. i will look into it some more. i greatly appreciate everyones input.

Re: Feeders Plugged

Posted on 4. Apr. 2007 - 01:32

If you ran continuously without plugging it suggests that the hopper is OK as long as material keeps moving and is not allowed to compact for very long.

You seem to be leaving a small amount of material in the hopper at the end of the run, presumably to prevent flushing material through the feeder when more material is dumped in. It is the settling of this material which seems to start your problem.

We have built hoppers which are designed to be emptied after each truckload is put through. We install a motorized gate to close off the feeder opening. After material is dumped in, the gate opens to the desired height then feeding starts. When the hopper is empty, the gate automatically closes before the next truck dumps.

Don't know if starting from scratch each time will work for you but you could try it under controlled conditions (ie run the hopper out, then dump small amounts until the opening is covered)

Another Possibility

Posted on 14. Apr. 2007 - 05:27

Rereading some of the answers again......i still get the feeling the system was in fact running fine for a long time.

Maybe, try troubleshooting the feeders:

You said mechanical.........by electric motor or ELECTRO MAGNETIC STYLE?

What type of spring system? I assume cable hung from above the reclaim belt below. It is possible...these feeders may not be vibrating FREE FLOATING. If material is flushed or compacted around the vibrating body or an interference fit the feeders will not FEED PROPERLY.......and the material will BACKUP and plug mr. feed chutework.

SPRINGS could be baked, tired, worn-out in need of new springs. If springs are LAX...the feeder is LAZY...AND will not deal with the tonnage. If electro magnetic....they may need to be shimmed to maintain the proper GAP for proper vibration to the pan. A stroke check would be very helpful to identify the stroke on the body.

DID you add any extra liners to these feeders.....from original? If you did you could have KILLED the stroke and caused a problem.

Feeding lots of questions to ponder for your review.....

Best Regards, George Baker Regional Sales Manager - Canada TELSMITH Inc Mequon, WI 1-519-242-6664 Cell E: (work) [email]gbaker@telsmith.com[/email] E: (home) [email] gggman353@gmail.com[/email] website: [url]www.telsmith.com[/url] Manufacturer of portable, modular and stationary mineral processing equipment for the aggregate and mining industries.
(not verified)

Plug Feeders

Posted on 14. Apr. 2007 - 03:43

Hello Coal processors,

I clicked on the Plug feeder forum because I design and build my own plug feeders, hoping to learn something from you guys, but I am not in the coal business..., and unfortunately, it does not look like I can learn anything from you.

The bulk solid we handle is ground up aromatic Cedar (10 mesh and under), which has a "bridging" problem much worse than coal.

Therefore we decided long ago to get V-shaped hoppers out of our lives..., except for very small 200-400 cuft hoppers with heavy duty, 1/4 pitch hard-surfaces screws, with vigorous vibrators on the V-sides of the open-top hopper.

Such small hoppers which feed continuously into our steam stripping process through a home-made plug feeder (the only one that seems to work), are fed either from large square, flat-bottom boxes with live bottom chains, or with a front end loader taking the chips from a huge pile (pile is under a covered metal shed).

Sure, huge hoppers eliminate one man on a front end loader, but this is an easy and popular job, easy to fill, and loaders are everywhere. We found that the cost of one man and one simple loader is easily offset by the loss of income from downtime, and repairs.

Forget the 1000 tons hoppers, and live happily.

Good luck

Gueric Boucard, Pres.

Texarome Inc.

Re: Feeders Plugged

Posted on 15. Apr. 2007 - 12:17

Hi Jnole,

Trying to modify a system to correct an problem elsewhere can be stressful, costly and ineffective. Your plant ran well before you changed the operation so leave it as is.

The problem stems from running fines and slop onto the left over coal in the hopper. This fills the gaps between the coal particles and allows it to set. You coal is acting like a sieve allowing water through and retaining the solids. When the good sized coal arrives it is loaded onto the sticky mess in the hopper encouraging it to set as it dewaters. When you have sufficient material to start the bridge has already formed.


Introduce de-watering chutes or other devices on the conveyors feeding the hopper. By taking the water out of the equation you should end up with a thin layer of debris on top of the retained coal which will not form a bridge and will dissipate as the coal draws down from the hopper.

Engicon specialises in correcting non-performing plants and low cost de-bottlenecking of systems.