Originally Posted by douglnij

Dear All

I enclose detail report for your reference. Please could help me to resolve this problem

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Am I correct in assuming the entire hopper is not lined with Tivar? If this is so you need to line the entire interior of the hopper over the weigh feeder

If the hopper is not fully lined with tivar it will stick and stay there.

There are several grades of Tivar including what is referred to as greased lightning tivar liner material. you may not have the right Tivar for the hopper.

finer particles will separate much quicker as they will behave like water and follow the easiest path as they have les surface area.

1. Short of relining perhaps an air cannon in the corners is the quick and the best answer short term.

2. Possibly simply blocking the corners with AR plate to act as baffles and reduce build up by eliminating the corners in the hopper is an answer as well.

3. Speeding up the weigh feeder is another option if possible weighing smaller batches continuosly ■

Originally Posted by douglnij

The dropping material from conveyor falls on it and may damge the TIVAR surface.

This is a problem as UHMW type materials suffer from wear from material impact. A common remedy is to locally replace the UHMW with abrasion resistant steel at the impact point retaining the UHMW for it's flow properties in the remainder of the hopper section. ■

Originally Posted by douglnij

Thanks for your suggestions.

We dropped down the TIVAR installation because it does not suitable for the following situation. The dropping material from conveyor falls on it and may damge the TIVAR surface. Also, we could use th Air cannons because we installed load cell to measure bin capacity with controls.

Could you detail the installation procedure of AR plate in coners. It will help us

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Greetings and salutations,

Adding the AR plate is easy to do just time consuming,

by welding or bolting a wedge of AR plate at each corner it does not allow the ore to fall to the corners.

If it were me-

1. Measure the vertical interior height of the hopper from the bottom of one corner to the top of the hopper-assuming you wish to stop with the AR plate at the joining seam; this will give you the height of the triangular piece of AR plate.

2. cheat and get some cardboard cut it to size for a triangular wedge and place it in one corner of the hopper to see if that amount of AR plate(height) would be enough to help remove the problem of bridging.

3. settle on one size of AR plate for one or two corners, cut the plate using the narrow cardboard triangle as a template.

4. tack weld it into place and run a load or two in it to see if the flow behaves, if you are satisfied finish the welds.

by closing off the corners there is less room for the ore to slide and if near vertical no where for it to go but down.

leon ■

The hopper design looks good TIVAR only lasted six week as polymers are not very good with erosive wear. SS plate option on impact region is good. You can also maintain a level in the silo so that the material does not fall on silo walls to reduce wear. Hopefully you can go back to mass flow with no problems

In my opinion you should also look at the apron feeder silo interface bit more closely. Is it drawing material across the whole outlet? or it is developing stagnant zones in the silo. If the silo is mass flowing, segregation will not be a problem as the material will be drawn evenly and concentration of fines to coarse will be consistent downstream. ■

Basically, the aspect ration of the hopper outlet (length/width) is too great for a simple feeder as indicated. To get good discharge you need to extract some material from the entire length of the outlet. I would suspect (but you can advise) that material feeds preferentially for the back of the hopper (the end away from the feeder discharge).

Suggest you discuss the problems with the hopper designer and the feeder manufacturer and ask for their solutions to the problems. ■

Originally Posted by douglnij

Please see the attachment

Could you please add the direction of movement of the feeder. ■

Originally Posted by designer

Could you please add the direction of movement of the feeder.

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Mantoo is right as far as shorting the silo to aid in feeding more material consistantly by the flow always chasing the demand from the apron weigh feeder.

It may be much simpler to short the silo(reduce feed into weigh feeder and deliver the lower tonnage without doing any work and possibly adding an air cannon on the front side of the hopper to dislodge any build up.

designer-I think the flow is toward the filled end of the hopper in the first photo strictly from the way it appears.

leon ■

Originally Posted by lzaharis

designer-I think the flow is toward the filled end of the hopper in the first photo strictly from the way it appears.

That's what I would expect, but I just wanted clarification.

My personal opinion as I said before is that the aspect ratio (about 5.7:1) is too high for this feeder type. I think the only type of feeder to extract from the full outlet length so keeping all material 'live' to avoid arching across the outlet would be a screw feeder with varying flight pitch and/or varying core diameter. ■

Hello Douglnij,

As I understand, you did not install a TIVAR lining into the raw mill feed bin. Is my understanding correct? While TIVAR and other grades UHMW do not stand up to severe impact abrasion, they work well in sliding abrasion. If there is an impact area, we typically install an AR steel impact plate or ceramic embedded urethane plate in the impact zone and line around it with TIVAR. We also fabricate and supply TIVAR corner clean-out plates to install in corners to eliminate sticking in and around corners. We have successfully lined limestone bins in the past experiencing no problems with flow, ratholing, or segregation.

May I suggest you contact Frankie Neo with Manga-Tag Pte Ltd. Manga-Tag is a SystemTIVAR distributor and installer of TIVAR linings systems.

Frankie Neo

Mobile: 9639 1989

80 Genting Lane, #07-02 Genting Block, Ruby Industrial Complex,

Singapore 349565

Tel: (65) 6745 2988

Fax: (65) 6841 0301

email: magnatag@singnet.com.sg / frankieneo@kalasia.com.sg ■

The problem is likely to be with the transition to the apron feeder. The details were not given, however, with the 6.5 aspect ratio of length to width, the transition will have to be correctly designed to result in an even draw along the length of the slot. Without an even draw, the apron feeder pull material from the most upstream section, filling the available space and not allowing any material to feed from the downstream section of the slot. This will create an active flow channel approximately equal (in diameter) to the width of the slot. If the critical arching dimension is smaller than this channel, flow will be interrupted. If not, the active flow cannel will empty a rathole to the top surface of the hopper.

A proper transition design will draw equally along the length of the slot. If the critical arching dimension is less than twice the slot width, no arch will occur. If the critical rathole dimension is less than the diagonal length of the slot, no rathole will occur and the material active flow channel will likely extend to the hopper walls (mass flow). The properties for the critical arching, ratholing and wall friction angle should be determined from the fines at the maximum anticipated moisture level and clay content.

The key step is to be certain that the transition is properly designed. We can provide this type of design if you are interested.

tel: 805-544-3775

FAX: 805-549-8282

email: info@diamondbacktechnology.com ■

Originally Posted by ldudley

The key step is to be certain that the transition is properly designed.

I'm sure we would all be interested to hear your concepts for the bunker/feeder transition with such a high aspect ratio. ■

Originally Posted by douglnij

the feed direction in long side , reference to first photo- from bottom to upward

That's interesting, so the arching is over the "back" of the feeder (where the empty feeder apron enters the bunker) not the "front" (where material is being discharged) as I had speculated.

Have you done as I suggested and contacted the hopper designer and feeder manufacturer? ■

Primasonics Acoustic Cleaners can provide a very effective and automated solution to this problem just as we have done previously. If you are interested in our ecomonical proposal, please e-mail me at - don@primasonics.com - and I will be pleased to outline our proposal. Simply by using the correct frequency of sound waves for a few seconds at periodic intervals, all internal material build up will be prevented fro occuring in the first place.

I look forward to receiving your e-mail and in the meanwhile please have a look at our web site - www.primasonics.com

Best regards

Donald F Cameron

Primasonics International Limited ■

Douglnij:

I believe CDI can show the following using Discrete Element Modeling:

1. Modeling of slot opening and present behavior that does not achieve mass flow

2. Simple modification to slot that provides mass flow, assuming rock size is in necessary range - model same that demonstrates proposition - I believe this will also achieve a better size distribution balance

3. Reason for segregation and corrective action required - will need dimensional details of discharge pulley and feed chute its orientation along with belt speed, width, transition idler configuration and rock size details

4. Ratholing deposition has been spoken about in earlier postings - seems memories and cognition are short - once ratholing is understood the task of eliminating it will be easier

Having said the above, I offer a guarantee - no benefit, no pay - achieved state of benefit is paid for by time applied. We can be contacted from the below email. ■

forgot item 5:

Item 5. Use of an alternative liner that is more resistant to scoring than UHMW plastic and has a lower sliding coefficient of friction. ■

hi sorry to hear about your problem, there will be an engineering soloution around the corner so to speak!!if this problem escalated and the need arises to clean /remove product. please give me chance to quote on this taskwe are an industrial silo cleaning company with many discaplines under our belt also many lkarge scale clean outs ranging from 20 tonne bins to 4000 tonnes silosregards Scott BeechingProjects Managerscott@intechenvironmental.com...ironmental.com ■