Originally Posted by cementhead

So you are saying that you have successfully controlled electromagentic feeders to approx a 5 to 1 turndown? If you don't mind my asking, where and on what type of material? This may be a factor in their success.

For medium-sized rates we have had great success using the Arbo Engineering vibratory feeders. They have an electromagnetic design and claim 1000:1 turndown. While I have never tested that claim, I have experienced that the turndown is very impressive. Read more about the Arbo Resonant Vibratory System here: http://www.arbo-feeders.com/images/pdf/RVSdualmass1.pdf

What is the rate range you require? ■

Originally Posted by cementhead

Hello All

Looking for some feedback from equipment users.

While at Lafarge I visited many plants in North America. Back then Roberta was one. As is the case in many places vibrating feeders (aka dust generators) are used to extract limestone in the tunnels under the storage piles. I sat with the operators one day and we tried varying the signal sent to the feeders to change the flow coming from them. From what I can remember over the full signal range I was lucky if we could see a 5% variance in flow through the vibrating feeder. Later on a project in Cave in Rock the quarry wanted to replace all their feeders for aprons for the same reason and the fact that they were all at the end of their usable life.

I now have a senior supervisor telling me that he has controlled vibrating feeders and obtained up to a 5 to 1 turn down using them. I replied there must be five of them installed and you turn all but one off. Though I maybe wrong. Maybe if properly installed people can accurately control these animals. Probably not to a 5 to 1 turn down but 2 to 1 might even be nice.

I would appreciate any feedback and personal experience anyone can share on the subject.

thanking you in advance

Originally Posted by johngateley

Firstly, either the 5% variance might have been adequate: otherwise there was no point in replacing them with aprons in a similar plant. Yes, dust is a severe problem with open feeders unless the moisture is just right to balance dust and stiction. You can provide an enclosure for screens and feeders to limit the dust down to habitable levels. A diaphragm isolates the vibrator from the sealing scantling and that's about all there is to it.

A turn down of 5:1 does seem ambitious and should be academic rather than process driven.

I used electromagnetic feeders with coal, rail delivered, out of bins. Feed rate was required constant and the priority was to put a steady load on the belt, what else? So the feeder was used to iron out the discrepancies in bin outlet flow caused by the climatics. Sometimes we didn't even use a belt weigher because the feeder was either working or broken and since it was a reliable Lockers device it was never broken.

Apron feeders are a curse in open air and working in confines spaces they are even more of a curse. They are no more reliable than alternatives: they are just heavier and clumsier. Fitters love them though because they can see the overtime building up as the delivery truck approaches the mine entrance. My own jaded opinion is that apron feeders should be sold as scrap the moment they arrive. It will save money in the long run!

Originally Posted by Roland Heilmann

Hello cementhead,

there's two main drive principles to vibrating feeders, that is the electromagnetic drive and the imbalance drive principle. When the latter could reach higher throughputs, it is the former which might be regulated to the mentioned ratio, and even better if required. So those are primarily suitable for dosing purposes at lower throughput values. However, these electromagnetic driven feeders are to my knowledge not quite able to support the load of the bulk pillar out of the bin or bunker, whereas imbalance driven feeders do perform under full bulk pressure.

Regards

R.

Originally Posted by cementhead

Thank you for the feedback Roland

So you are saying that you have successfully controlled electromagentic feeders to approx a 5 to 1 turndown? If you don't mind my asking, where and on what type of material? This may be a factor in their success. I guess I am to assume you have has less luck with the electromechanical ones?

Hi John

I also see vibrating feeders as a more on/off machine and if you want to vary this flow you manually change their angle and leave it this way.

I have to say I am a little surprised with your comments on apron feeders. I have seen them successfully installed in many Lafarge installations and they get installed and forgotten about. I do agree that when wear becomes an issue they are quite the prize to work on in tunnels. Thanks for your feedback.

Liam

Originally Posted by Roland Heilmann

Hello Liam,

i did not have the controls to such a feeder, i merely wanted to clarify what seemed to me being a misunderstanding as mentioned in your primary post. So like as to ask back your supervisor if he could have had in mind just that different drive principle.

The high througput / little turndown vibrating conveyors are those to be met in the bulk industry as feeders. The small throughput / high turndown appliances with the electromagnetic drives i have seen in the cement / concrete / building materials industry --> aggregates, and heard of to be used in foundries. But this is from really quite some time ago.

Regards

R.

Originally Posted by Delmar

For medium-sized rates we have had great success using the Arbo Engineering vibratory feeders. They have an electromagnetic design and claim 1000:1 turndown. While I have never tested that claim, I have experienced that the turndown is very impressive. Read more about the Arbo Resonant Vibratory System here: http://www.arbo-feeders.com/images/pdf/RVSdualmass1.pdf

What is the rate range you require?

Originally Posted by cementhead

In the past the feeder tonnages I was working with on limestone were in the 200 to 300 tph each range. I currently have an application where I will be in the 3000 tph - 6000 tph range each on iron ore and am working with suppliers to see what and or if they can supply.

========================================================================================

Hagglunds, NICO and METSO apron feeders come to mind in this instance

Even though my dear friend john and are at polar opposites about

apron feeders the issues of ore transfer from stockpiles or bunkers

are enormous and complicated.

John has discussed this in great detail illustrating issues with

controlled mass flows, surge flows, bridging, ratholing,

moisture content of ores and last but not least the sizing issue

which John will agree tends to make manure flow up hill to the

management if transfer problems exist or deaths occur.

IF the recieving bin is not designed properly where the draw point diameter

is not sized to properly to create mass flow at the bottom of the hopper all hope

is lost!!!!!! ■

Originally Posted by cementhead

Hello All

Looking for some feedback from equipment users.

.... From what I can remember over the full signal range I was lucky if we could see a 5% variance in flow through the vibrating feeder. Later on a project in Cave in Rock the quarry wanted to replace all their feeders for aprons for the same reason and the fact that they were all at the end of their usable life.

I now have a senior supervisor telling me that he has controlled vibrating feeders and obtained up to a 5 to 1 turn down using them. I replied there must be five of them installed and you turn all but one off. Though I maybe wrong. Maybe if properly installed people can accurately control these animals. Probably not to a 5 to 1 turn down but 2 to 1 might even be nice.

I would appreciate any feedback and personal experience anyone can share on the subject.

thanking you in advance

Firstly, either the 5% variance might have been adequate: otherwise there was no point in replacing them with aprons in a similar plant. Yes, dust is a severe problem with open feeders unless the moisture is just right to balance dust and stiction. You can provide an enclosure for screens and feeders to limit the dust down to habitable levels. A diaphragm isolates the vibrator from the sealing scantling and that's about all there is to it.

A turn down of 5:1 does seem ambitious and should be academic rather than process driven.

I used electromagnetic feeders with coal, rail delivered, out of bins. Feed rate was required constant and the priority was to put a steady load on the belt, what else? So the feeder was used to iron out the discrepancies in bin outlet flow caused by the climatics. Sometimes we didn't even use a belt weigher because the feeder was either working or broken and since it was a reliable Lockers device it was never broken.

Apron feeders are a curse in open air and working in confines spaces they are even more of a curse. They are no more reliable than alternatives: they are just heavier and clumsier. Fitters love them though because they can see the overtime building up as the delivery truck approaches the mine entrance. My own jaded opinion is that apron feeders should be sold as scrap the moment they arrive. It will save money in the long run! ■

Hello,

Vibrating feeders (electromagnetic or mechanical type) are recognised equipment for controlled feed to the receiving equipment. These are extensively used for such application. It is well known that vibrating feeder can vary the discharge from dribble to full capacity. However, every type of feeder has also limitation for application, which will amount to poor performance as end result.

1) For this particular case, one has to see whether vibrating feeder is suitable for the application (material size, adequate space for proper layout, etc.).

2) In case of vibrating feeder, the layout arrangement is crucial for feeding of material onto the tray. Firstly, the feed chute should direct the material onto the tray at proper velocity, including direction. It should not come at more speed such that it will get discharged on its own. The stagnant material (when feeder is not working), should rest on the tray keeping at least 300 to 400 mm clearance from the tray edge, according to repose angle of the material. There should be one control gate to choose the opening height above tray, for optimum performance of the feeder. Bulk materials are heterogeneous in nature and it is difficult to predict exact behaviour of the particular material, as to be handled, and so such gate is essential as a remedial measure during installation and commissioning. In general, such gate will remain in the same setting, unless there is need to adjust later.

The vibrating feeder if installed at more inclination, will give more capacity and economy. But this should be avoided. The feeder proper inclination will depend upon material.

3) The feeding condition should be stabilised in nature, to facilitate the proper performance of vibrating feeder. The residual material in hopper or above the feed chute should always be there, to the extent possible. In case of hopper this can be achieved by low level switch, if feasible.

Lesser inclination of the tray and also longer tray will result into better control of the discharge, but make the VF more expensive.

4) The vibration frequency and amplitude should be suitable for the application.

Ishwar G. Mulani

Author of Book : Engineering Science And Application Design For Belt Conveyors (new print November, 2012)

Author of Book : Belt Feeder Design And Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Pune, India.

Tel.: 0091 (0)20 25871916

Email: conveyor.ishwar.mulani@gmail.com

Website: www.conveyor.ishwarmulani.com ■

I have operated and maintained few vibrating feeders supplied by Ms Hewitt Robbins in1965.They were working on unbalanced wight principle.It was driven by Slip ring motors for speed control. The vibrating feeders required good condition monitoring, not FIT and FORGET. The material handled was Iron ore both lumpy and fines.

These VF were installed under 200tons surge bins (loading capacity 2500TPH). The unbalanced shaft failed after about 10years of operation and were replaced with VOLTAS make shafts. The system with proper/timely maintenance was working well for over 20 years.

Dust,sound and vibration of the structures are issues which I felt serious matters to be considered in case of VF.

Narayanan Nalinakshan.

Originally Posted by I G Mulani

Hello,

Vibrating feeders (electromagnetic or mechanical type) are recognised equipment for controlled feed to the receiving equipment. These are extensively used for such application. It is well known that vibrating feeder can vary the discharge from dribble to full capacity. However, every type of feeder has also limitation for application, which will amount to poor performance as end result.

1) For this particular case, one has to see whether vibrating feeder is suitable for the application (material size, adequate space for proper layout, etc.).

2) In case of vibrating feeder, the layout arrangement is crucial for feeding of material onto the tray. Firstly, the feed chute should direct the material onto the tray at proper velocity, including direction. It should not come at more speed such that it will get discharged on its own. The stagnant material (when feeder is not working), should rest on the tray keeping at least 300 to 400 mm clearance from the tray edge, according to repose angle of the material. There should be one control gate to choose the opening height above tray, for optimum performance of the feeder. Bulk materials are heterogeneous in nature and it is difficult to predict exact behaviour of the particular material, as to be handled, and so such gate is essential as a remedial measure during installation and commissioning. In general, such gate will remain in the same setting, unless there is need to adjust later.

The vibrating feeder if installed at more inclination, will give more capacity and economy. But this should be avoided. The feeder proper inclination will depend upon material.

3) The feeding condition should be stabilised in nature, to facilitate the proper performance of vibrating feeder. The residual material in hopper or above the feed chute should always be there, to the extent possible. In case of hopper this can be achieved by low level switch, if feasible.

Lesser inclination of the tray and also longer tray will result into better control of the discharge, but make the VF more expensive.

4) The vibration frequency and amplitude should be suitable for the application.

Ishwar G. Mulani

Author of Book : Engineering Science And Application Design For Belt Conveyors (new print November, 2012)

Author of Book : Belt Feeder Design And Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Pune, India.

Tel.: 0091 (0)20 25871916

Email: conveyor.ishwar.mulani@gmail.com

Website: www.conveyor.ishwarmulani.com

■

I am agree with Mr. Mulani that you should consider vibrating feeder and bin arrangement. Maybe your bottleneck is bin discharge dimension not the vibrating feeder to receive the capacity.

Meanwhile for 3000 ton per hour capacity, I think the only choice is unbalanced motor vibrating feeders not electromagnetic. for unbalanced motor you can change the capacity with frequency converter online and changing unbalance offline. ■

A vibrating feeder should work for what you are trying to do. With the correct vibratory feeder, good electromagnetic drive, and good feeding controller, you should be able to get the feed rate that you want. You should check out 3Sigma's Geomate Vibratory Feeder. There are also case histories of the feeder on the website.

www.3sigma.biz ■

Dear Sir: mostly ELECTROMAGNETIC feeders are the common type used for these apps. FEED rate can typically be fixed speed and or variable by control as the norm. Biggest problem I see in my travels is the EM Feeders are typically NOT maintained properly hence it proves to be difficult to vary the federate period. Quite often can be a problem especially in a BIG union operation or just a big operation...due to the fact EM feeders need to be GAP SHIMMED TO maintain proper stroke and proper feed rate. When opening the motors..they are kinda part mechanical shimming fix and oops.....some electrical aspect which one of those 2 trades leave something short of a full fix quite often.

The Electromagnetic feeders do a great job normally...usually installed at about 10 slope heading to the belt and multiple feeders depending on the TONS being fed to mr conveyor belt.

They are efficient, not overly expensive and if properly gapped, should be easy to vary the feed rate. APRON feeders for that app are somewhat of a mechanical overkill.

George Baker

MODERATOR

Originally Posted by cementhead

Hello All

Looking for some feedback from equipment users.

While at Lafarge I visited many plants in North America. Back then Roberta was one. As is the case in many places vibrating feeders (aka dust generators) are used to extract limestone in the tunnels under the storage piles. I sat with the operators one day and we tried varying the signal sent to the feeders to change the flow coming from them. From what I can remember over the full signal range I was lucky if we could see a 5% variance in flow through the vibrating feeder. Later on a project in Cave in Rock the quarry wanted to replace all their feeders for aprons for the same reason and the fact that they were all at the end of their usable life.

I now have a senior supervisor telling me that he has controlled vibrating feeders and obtained up to a 5 to 1 turn down using them. I replied there must be five of them installed and you turn all but one off. Though I maybe wrong. Maybe if properly installed people can accurately control these animals. Probably not to a 5 to 1 turn down but 2 to 1 might even be nice.

I would appreciate any feedback and personal experience anyone can share on the subject.

thanking you in advance

■