No such a thing available that I am aware of. The design of every chute is unique to the system and you would need to custom design something if it is even possible.

Your issue is most likely improper design of the chute in the first place. I would take a major look at the design of the chute before attempting to put a band aid on the problem. ■

I agree with Gary that alternative chute design would probably be a more worthwhile pursuit. I've never seen this done, but I'd wonder if you may be able to incorporate oscillating vibrators, similar to what you would see on a shaker table, on the bottom of the chute to try to keep material flowing. You'd probably have to dampen your reactions to the structure.

I've also been informed that there may be air cannon solutions, where a pneumatic cannon is triggered by a plugged chute switch and fires to attempt to dislodge the material. ■

I would be concerned with vibrators packing the chute even harder.

In addition to eshimek's comments about a pneumatic cannon - there is a company called Flow Industries that have developed a high pressure air injector that might be worth looking at. http://www.flow-industries.com/113158/Silo-Flow-new ■

Originally Posted by lukazi

Thanks for your reply. That sounds like an excellent idea. I'm just a bit suspicious how the canons would cover such a large area inside the chute and still have very high pressure.

Would you have any link to this solution?

As a disclaimer, I do not have any personal experience with these systems. So, I can not verify their viability for your application. I've included a few links to providers below. I'd imagine their reps can provide a much better idea of how effective they will be for iron ore with high moisture.

http://www.vibco.com/docs/catalogs/v...on-catalog.pdf

https://www.martin-eng.com/sites/def...w-problems.pdf

http://products.airmatic.com/categor...nnons-controls

http://www.brelko.com/download/catal...Air-Cannon.pdf

During my search, I also came across an old Bulk-Online post of an air cannon application in South Africa, through Martin Engineering:

https://forum.bulk-online.com/showth...Chute-Build-Up ■

FYI:

http://www.google.com/patents/WO2009009894A1?cl=en

Regards,

Lyle ■

Sticky ores, as we all seem to agree, stick. When the blockage is first observed compaction has already taken place and tedious vibration, poking, flushing and air blasting are usually undertaken. I have yet to see the issue of relaxing the compaction properly addressed. I once proposed relaxation by adjusting slotted holes in the impact plate (some arrogant poster tells me there shouldn't be impact....so why have a chute at all?). If the slots are long enough they will permit cleaning access. Of course you have to restore the original setting or else look daft. Accept that sticky ores will create a blocked chute condition regularly: because they have done so throughout history; do so still; and will continue to do so far into the future. Space scientists among us, and there are plenty, cannot give a straight answer to the phenomenon although they make some amusing claims. If something, however well designed, is going to fail it surely needs to be easier to fix. I must admit that I don't know what improvement slotted holes would make because the nickel miner went tits up before anything got made.

Can somebody up there please tell me why there is an enormous red patch over my right eye. That is my good/better eye and probably deserves a 95% rating. ■

Another Idea on Plugging Control:

1. We have used vibration - need to quantify frequency, amplitude, power to oscillate mass of metal impact and ore attached

2. Others have used water dribble to break adhesion with success.

3. Better to optimize the chute geometry that may eliminate (highly reduce) impact action and adhesion strength.

4. Offer this bit of tiger meat - we have been successful in calibrating ore cohesion and adhesion strengths within our DEM code ROCKY and then applied the properties to chutes that first demo or synthesize the plugging action, and then redefine the chute geometry and maybe vibration surface that shows flow can be controlled without plugging.

5. Worked in Australian, India, and China iron ore transfers along with stickier bauxite, nickel, copper concentrate, and lignite coal with success. ■

Thank you for kind drawing our attention to the sticking problems in bulk materials handling.

The best way is to decrease the friction coefficient. An other way ist to use the gravitation to change the direction.

This is an scientific area open to innovations and patents.

Thank you.

Dr. H. Ergun ■

Regarding the comparison with space travel and ore chutes the matter is quite simply the difference between miners and stargazers, as you said. Chutes were devised for coal because at the time coal was the main material handled in bulk. It still is important in some locations. It was only natural that chutes would be applied to ores as the demand for ores developed. Coal problems were already known and solutions were somewhat available. This was not so for ore handling. As commodity prices fluctuate new ore deposits are developed and new properties are exposed. Despite what experts will tell you in the coming replies there is no reliable answer to chute blocking. Chute have blocked, do block and will always block. There is no automatic method for unblocking a stuck chute. Water will play havoc with the downstream process and make an ugly plant, aren't they all, even uglier. Vibration will shake the blockage into a more compact denser mess and air cannons should be restricted to materials that can breathe. Miners are one of the ultimate conservatives and terrified of new developments so most people gave up long ago.

When something is flawed the NASA type will examine the problem thoroughly and provide whatever solutions are necessary to meet the demands. Mineral processors will pretend the problem doesn't exist: confident that they will make enough cash to overlook the deficiencies. They are covered by ore body fluctuations, climate and metal prices.

There is no need for an automatic chute clearer because the time spent clearing is compensated by the revenue gained. Ore is generally quite worthless until it has been processed and the scale of that processing is enormous. Blocked chutes are insignificant until someone has to get down to clearing the chute and in the great scheme of mining those people don't hold much sway. ■

Originally Posted by johngateley

Can somebody up there please tell me why there is an enormous red patch over my right eye. That is my good/better eye and probably deserves a 95% rating.

You are the only one that can see that John. Hold your mouse over the "red patch" and your question will be answered. Finish your " Who is Who" profile and you will no longer see it. ■

Hello,

Lignite coming from mine (at mine head) is often classified as wet, sluggish, sticky and also more abrasive than coal due to presence of sandy particles. This material is successfully and regularly handled by lignite handling system (conveyors, crushers, screens, stackers, reclaimers, and their chute work). You can visit to see the system in power plant at some lignite mine head.

As I remember, the lignite handling transfer point chute includes steps for material free fall, impact on sharply inclined face, sharply inclined chute, S.S. liners, etc. The basic design velocity of material in chute is considered comparatively higher so that it tends to create self cleaning situation all the time even though it amounts to higher velocity while landing in receiving equipment (during dry condition). This is to be taken care by proper belt and idlers.

The iron ore bulk density is about 2.5 times lignite, and is to be taken care accordingly. This means material momentum component creating sticking as well as its component resisting sticking, both will be 2.5 times. If you are handling iron ore (-) 100 mm then solution can be similar to lignite (use appropriate liner to withstand more abrasion). If it is mixture of big lumps and fines then the chute work design would defer prior to crushing and after crushing.

When chute work is designed properly at each location (case to case basis), then flow will be proper for the applicable characteristics of material. The properly designed chute (as an engineered item) also influences relative location of equipment vertically and horizontally. In case of existing plant, the modification will be more demanding in nature.

The information is to be treated as hints.

Regards,

Ishwar G. Mulani

Author of Book: ‘Engineering Science And Application Design For Belt Conveyors’. Conveyor design basis ISO (thereby book is helpful to design conveyors as per national standards of most of the countries across world). New print Nov., 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 ■

Water flushing often clears a chute. Manually of otherwise where does the water go? Into the following equipment. Is it quantified in the downstream process? Some plants thrive on salt water, others don't. Water is the biggest problem when handling dry bulk. If you dry the product in the interests of flow-ability then the chemists will be upset and the owner will be outraged by financing drying only to see the product re-moistened as required by the downstream process.

Inflatable liners promote flow for a very finite period. Then they get ripped to shreds whether the ore is wet or dry. Replacing such liners, oops, nearly said discarding, will take longer than clearing a steel lined chute. I've tried 'em all and advise that there is no known solution to ore blockages manual or otherwise. If there was most of us would be looking for jobs elsewhere.

Many usual flow promotion pundits are noticeably absent from this thread. If they have given up what chance have we mortals? ■

Dear Lukazi,

Transfer chute cleaning is just part of your problems. We have successfully designed, installed a number of transfers with very sticky ores in the iron ore industry that NEVER block regardless. We do this through controlled flow through the chute, we have a paper in this Forum on it and have recently published a further paper. Instead of looking to a remedy, try a solution. Chutes can be designed for wet sticky ore that do not block, load centrally and without impact so you do not need impact idlers nor hard faced skirt systems and where maintenance overall is minimal. We continue to have success in this area to the point we now guarantee such outcomes.

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

You might as well give Colin's methods a try because they should be cheaper than the methods you have so far.

Even if it doesn't live up to claims exactly then you can go back to hoses.

If improved chutes only reduce blockage frequency by 20% the saving on downtime will be very pleasing. ■

Originally Posted by lukazi

Hello everyone,

I work in iron ore industry and one of the biggest problems we have, with a heavy impact on production, are chute blockages. They cause massive amount of delays. The way we deal with this at the moment is simply by opening chute doors and cleaning them manually. We require very high water pressure and often a lot of time to clean only one chute, due to sticky ore and heavy bulldup.

Is anyone aware of any automatic cleaning technology?

Added by Adminstirator as an example only:

Conveyor Design Software

I have read all the advice given and agree to the content of each of the subscribers comments. I also have had sticky product to handle, Mangrove Mud, Mineral Sands, Clay, Coal & Metalliferous Products. There are some aids to reduction in the blockage systems and it really depends on a competent chute design as a start. I personally have used a modified impact plate design and a non-foaming 'BP Comprox' dishwashing solution with a continual low pressure spray into specially designed cavities to add aeration to the flowing product over the impact plate design. The BP Comprox breaks the surface tension of the stickiness of the inherent contained water moisture allowing the product to become somewhat non-packing and this aids in reducing blockages. It also aids in the reduction of the cleaning energy necessary to clear the blockages as they (the blockages) will always happen to some degree due to 'Murphy's Law' "What can go Wrong, Will go Wrong".

The BP Comprox useage will attract cost but will definately cheaper than the labour etc of cleaning.

Les ■

Originally Posted by lukazi

Thanks for your invaluable comment, as well as to the other posters.

So my understanding is that the slotted holes have never been trialled?

I'm just finding it hard to comprehend that we can spend people to space but we can't stop chute blockages..

How about multiple high pressure water nozzles strategically positioned inside the chute?

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

The only way you are going to clear the build up in the chutes is

to use a hot water steam cleaner like a Steam Jenny and use

Dawn Dish Soap to cut the clay.

The Steam Jenny needs filtered softened hot water to prevent the

hot water coils from plugging from lime scale.

www.steamjenny.com ■

As our experience for iron ore concentrate (below 70 micron with moisture content of about 10%), TIVAR(Tough Inert Very Abrasion Resistant) liner is very good.

TIVAR is one kind of UHMWPE.

Meanwhile I suggest take a look on Martin Foundations book, which include a chapter for engineered flow chutes. ■

Hi..

I think, You need some Polymer liner like UHMWPE or Poly eurethane liner with air blaster/vibrator .but design change is also a option but it requires detail checking by some material handling expert.

Regards,

Subho ■

Originally Posted by Gary Blenkhorn

No such a thing available that I am aware of. The design of every chute is unique to the system and you would need to custom design something if it is even possible.

Your issue is most likely improper design of the chute in the first place. I would take a major look at the design of the chute before attempting to put a band aid on the problem.

I agree with Gary that vibrators may cause more compaction, especially if the material has no where to go. You may look into Single Impact Knockers that can deliver one strike on a timed interval. These are our weapon of choice for sticky material that tends to compact under continuous vibration. You get one jolt every few seconds to break material bonds and let gravity take over between strikes.

http://www.clevelandvibrator.com/Pro...5/1500-SI.aspx ■

Hi, read your thread on chute build up. Something you may want to consider is utilizing a product manufactured by Benetech Inc, Aurora IL. They have a small compact air blaster that blows high pressure air (80-100 PSI) radially along a chute wall. Can be installed in all types of chute material liners. Best thing I see with this product is they can be placed where the build up first occurs (dog leg, ledge, impact zone etc) and don't require an outage to install. As you have experienced, your buildup is starting in one location and then builds upon itself until the entire chute is plugged. I have recommended these devices to many of my consulting customers working with high clay content materials. They have proved very successful. The manufacturer will provide a 100% money back guarantee if they will not remove your buildup, keep the chute, hopper,ect open, Worth a call, could solve your problem and eliminate down time, confined space/safety problems. ■

Originally Posted by AES Consulting

Hi, read your thread on chute build up. Something you may want to consider is utilizing a product manufactured by Benetech Inc, Aurora IL. They have a small compact air blaster that blows high pressure air (80-100 PSI) radially along a chute wall. Can be installed in all types of chute material liners. Best thing I see with this product is they can be placed where the build up first occurs (dog leg, ledge, impact zone etc) and don't require an outage to install. As you have experienced, your buildup is starting in one location and then builds upon itself until the entire chute is plugged. I have recommended these devices to many of my consulting customers working with high clay content materials. They have proved very successful. The manufacturer will provide a 100% money back guarantee if they will not remove your buildup, keep the chute, hopper,ect open, Worth a call, could solve your problem and eliminate down time, confined space/safety problems.

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

Of all the respondents, in principle, I agree with Colin more than most others.

We do handle highly concentrated fine ground minerals of many types with chute flow simulation. These materials have aggressive cohesive and adhesive strengths, dependent on moisture and particle size distribution. I offer to simulate your worst chute, free of charge, to demonstrate its present behavior and then to show, by simulation, with same ore properties, a solution. If you use the solution and it is successful, you agree to pay the cost of the design. ■

Hi Larry,

The only way your simulation can be seen to work is they build a transfer. Your colleagues at Tunra and elsewhere have been trying to use DEM simulations to solve the design enigma of adhesive and cohesive materials and failed miserably, creating transfers that are maintenance nightmares. We have designed and built transfers for the most cohesive materials imaginable and with varying ore properties and the solutions resulted in very low maintenance, highly reliable transfers. I am not going into the issues with DEM here but we successful installations, where are yours

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

Originally Posted by Colin Benjamin

Hi Larry,

The only way your simulation can be seen to work is they build a transfer. Your colleagues at Tunra and elsewhere have been trying to use DEM simulations to solve the design enigma of adhesive and cohesive materials and failed miserably, creating transfers that are maintenance nightmares. We have designed and built transfers for the most cohesive materials imaginable and with varying ore properties and the solutions resulted in very low maintenance, highly reliable transfers. I am not going into the issues with DEM here but we successful installations, where are yours

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com

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

I will let Tunra and others answer your snarky comments about their failures. You make generic claims. Why not be bold and label the installation failures of the others and your claim to make right the same installations demonstrating your superior capabilities. Seems like a cheap shot by you, if you cannot demonstrate the claims.

Your first comment: Have we build chutes transporting wet sticky ores showing proof of ROCKY DEM principles - YES, many times.

You are becoming less professional in your responses - you seem to portray yourself as the only one with answers on chute flow. Too bad for your credibility. We cannot and have not argued with your success or lack of. This takes someone in your area to know about your results. Likewise, you do not work in our area of expertise, and know little about what we do. As such, how do you become an expert on our capabilities? I assume you do not have the necessary information to make such a claim. Prove me wrong.

For your information we have much success in the cement industries (wet, fine, limestone, clay, clinker) at multiple plants - iron ore concentrate, copper concentrate, moist potash, bauxite, moist alluvial dam and airport runway fill, ..... ■

Larry,

I am not going to get into another slanging match. The Transfer Chute performances in the Pilbara with below water table ores attests to the repeated failure of conventional and long accepted design methodologies to solving the design challenges that complex ores present especially when water is present and through this creating highly cohesive and sometimes adhesive ores. We will fully publish in due course but we have patented what we have developed using our research and the patent has now been granted in Australia and should follow soon elsewhere. There are just so many engineers blinded today by the computer generated magic of colored flow models on screens that they are not asking themselves why then does this not translate when the materials are complex. That is what we did and we could not find the answers by manipulating the algorithms in a DEM software package

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

Colin,

I believe we all wish mud slinging will stop. When you make Grand Claims at the expense of other engineers, it's only fair to backup your claims.

I observe you continue to claim special knowledge that are superior to all others and also claim to publish the results. I see none of it here in this forum or elsewhere. I believe I have read all of your posts and do not find your recent claims. You have used the same words in the past - "in due course you will witness our superior capability". However, nada. Everybody is waiting on these claims to see how you have made these great strides, others are not able to do. Good for you if you can do it. Nobody wishes you negative success. Prove you have it or stop talking about it, it's just baffle gab.

I did notify Tunra of you dissing their capabilities on chute modeling. I expect you will see a response from them soon. They know not what you claim. ■

Larry,

There is a paper I published sometime ago on the Forum (White Paper section), there is a recent article in the Australian Bulk Handling Review which I am more than willing to put on the Forum and then there is my patent which is in the published arena for those who want to look and given it is 68 pages and quite detailed, it also gives a lot of background to our work and where we have got to. So it is totally ingenuous to say we have not published, we have. Just most do not want to accept what we are saying. We have a lot more work to do and the more we do the more we realise how profoundly wrong some of the underlying tenets of the current "accepted" design approach to transfer design is. It also has very significant ramifications for the design of most other components in the material handling system but that is another story we will work on later.The fact you can get good results with reasonably simple materials really reflects the evolution of the mathematics rather than anything that has an underlying compelling logic. We have a great deal of work on right now and all going well we should have some very interesting things to report most probably next year

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

Dear Colin,

I have read the old white paper you published and did not find the explicit science that distinguished your technique. I have have not found your reference. Please offer the reference for this, and for any other relative reference you have published for all forum readers to gain access to.

In addition, can you offer the Patent No. you also reference.

I and others would be thankful for your cooperation. ■

Originally Posted by nordell

Dear Colin,

I have read the old white paper you published and did not find the explicit science that distinguished your technique. I have have not found your reference. Please offer the reference for this, and for any other relative reference you have published for all forum readers to gain access to.

In addition, can you offer the Patent No. you also reference.

I and others would be thankful for your cooperation.

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

Colin,

I poorly stated the above request. Can you reference where to find the White Paper you refer to? In addition can you offer the reference on other publications? ■

Larry,

If you go to the section on papers in the Forum and go to now to page 2 you will see the original paper and a reply by Peter Donecker. I previously referenced to you and others when we last had a discussion on transfers. The latest paper is in the Australian Bulk Materials Handling Journal that comes out every 2 months and was in the November/December issue of 2014, page 65 I believe. I will however look at putting this on the Forum although it is a relatively long paper. The patent can be accessed by doing a patent search under my name or Gulf. With all this however it is but a small part of what is the science of granular physics and to fully appreciate what we are saying and what we have done you need to read up on some of the latest books such as "Granular Media" by Andreotti, Forterre and Pouliquen. Published last year. Then you will get an appreciation as to why the complexity of granular flow does not lend itself at this stage to mathematical solutions as the simplification of the mathematical models require too many heroic assumptions. Sure for simple materials we can get some reasonable outcomes but do we need a computer to help us with these? I do not think so. I am where I am at not because I would not like a simple computer generated solution but because the computer generated solutions did not produce reasonable solutions. Through this I now question many of the underlying tenets we have used for flow modelling going back 30 odd years.

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

Originally Posted by Colin Benjamin

Larry,

If you go to the section on papers in the Forum and go to now to page 2 you will see the original paper and a reply by Peter Donecker. I previously referenced to you and others when we last had a discussion on transfers. The latest paper is in the Australian Bulk Materials Handling Journal that comes out every 2 months and was in the November/December issue of 2014, page 65 I believe. I will however look at putting this on the Forum although it is a relatively long paper. The patent can be accessed by doing a patent search under my name or Gulf. With all this however it is but a small part of what is the science of granular physics and to fully appreciate what we are saying and what we have done you need to read up on some of the latest books such as "Granular Media" by Andreotti, Forterre and Pouliquen. Published last year. Then you will get an appreciation as to why the complexity of granular flow does not lend itself at this stage to mathematical solutions as the simplification of the mathematical models require too many heroic assumptions. Sure for simple materials we can get some reasonable outcomes but do we need a computer to help us with these? I do not think so. I am where I am at not because I would not like a simple computer generated solution but because the computer generated solutions did not produce reasonable solutions. Through this I now question many of the underlying tenets we have used for flow modelling going back 30 odd years.

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com

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

Thanks for the postings.

I will read them with interest.

I will leave you with your technology.

We believe in what we have done and what we are about to do. You can do the same. You can continue to downplay other technologies. Time will decide the greater good. ■

Originally Posted by Colin Benjamin

Hi Larry,

The only way your simulation can be seen to work is they build a transfer. Your colleagues at Tunra and elsewhere have been trying to use DEM simulations to solve the design enigma of adhesive and cohesive materials and failed miserably, creating transfers that are maintenance nightmares. We have designed and built transfers for the most cohesive materials imaginable and with varying ore properties and the solutions resulted in very low maintenance, highly reliable transfers. I am not going into the issues with DEM here but we successful installations, where are yours

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com

Hi Colin,

I don’t participate in these forums but Larry has made us (TUNRA) aware of your comments. I have elected to respond on behalf of TUNRA, with the full support of my colleagues, as your comment regarding our capabilities is both disappointing and unprofessional. I agree wholeheartedly with Larry; I don’t understand the need for you to be negative about others for you to discuss your success.

Under the guidance of Prof Alan Roberts, TUNRA was formed to provide a service to Industry, which we have been doing successfully for 40 years. We continually improve our analysis methods through research with the University as well as run courses to educate Industry. We are always learning and our interactions with Industry are what allows for further development of analytical methods. We don’t pretend to have all the answers, rather we actively engage in improving the current understanding of materials handling. In fact, the advancement of bulk materials handling is what drives our group.

To reply to your post more specifically, you should know that the Discrete Element Method (DEM) is an internationally recognised research and consulting tool studied across numerous fields – if you want to search “DEM” and “cohesive” using google scholar there are many listed Academic papers showing the use of DEM with cohesive materials. We have many colleagues in different groups, from all over the world, who use DEM to solve industrial problems like we do. Keep in mind when you publicly criticise us you are also criticising them as well. You might also be interested to know that the University of Newcastle now includes DEM as part of its materials handling course offered to undergraduate students.

For your information, my colleagues and I at TUNRA have been involved in over 50 transfer chute projects (totalling over 100 chutes) in the last 2 years alone. In that period, we have had one Client come back to us with commissioning issues (due to new information) which we worked through with them and now have a successful installation. We are aware of no other issues with any of our designs; we are confident that had there been such issues we would have been contacted by the Client.

As I said, I do not frequent this forum so if you would like any further discussion I invite you to contact me directly. ■

Originally Posted by Tim Donohue

..... You might also be interested to know that the University of Newcastle now includes DEM as part of its materials handling course offered to undergraduate students.

......

I'm vaguely interested. To what depth is this inclusion?

There are 2 ways of looking at this development, probably more. It is rather premature to seduce students into reliance on a technology which, however laudable, is just emerging from infancy and not yet reached adolescence.

First option is that students will be reliant on unproven technology. Experienced engineers will then delight in rebuking the shortcomings even though it will be costly. That's engineering progress in a nutshell!

Secondly it could be interpreted as a sales pitch. It is one thing to introduce 3D cad packages to engineering students in general. It is quite another thing to expect firms to lash out on costly undeveloped software so that the undergraduates can demonstrate user ability.

Neither of these conflicting technologies work well enough and I urge you to admit it collectively, retreat into your ivory towers and let the mainstream continue to try to avoid or rectify the situations which you all claim to be able to solve with varying high degrees of success. May I point out that this thread started by asking about 'Automated Cleaning of Chutes.'. It has deteriorated into the usual slanging match and in this land of the blind, one king has a good right eye and the other has a good left eye. Would both dynasties care to reveal their costs? I am guessing that a textbook will work out cheaper then a DVD, outside a SE Asian Shopping Mall where the eventual cracked software will indubitably come out on top: for better or worse.

Academia should be left to....academics. Joan Rivers agrees. ■

it is interesting that thoughout this long discussion no one has mentioned measuring the 'stickiness' of the material being handled, the difference between static and dynamic friction and values of relative contact surfaces and finishes, or the merits of radius corners to avoid the large surface effect of square corners. Likewise, the influence of impact angle and velocity, acceleration of curvature are factors amenable to analysis, at least as a starting point for design. It would be widely useful to establish some basic design principles and perhaps examples of successful designs by users who do not have a commercial interest in chute design. ■

Originally Posted by Lyn Bates

it is interesting that thoughout this long discussion no one has mentioned measuring the 'stickiness' of the material being handled, the difference between static and dynamic friction and values of relative contact surfaces and finishes, or the merits of radius corners to avoid the large surface effect of square corners. Likewise, the influence of impact angle and velocity, acceleration of curvature are factors amenable to analysis, at least as a starting point for design. It would be widely useful to establish some basic design principles and perhaps examples of successful designs by users who do not have a commercial interest in chute design.

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

Hi Lynn,

Many have commented on Sticky particles as cohesion (particle to particle) and adhesion (particle to wall). What is not introduced is time or rate dependent properties of particle interactions such as Bingham Fluid, visco-elastic, visco-plastic, rheology models. These usually are secondary order effects. The magnitude of the properties requires knowledge of the model mechanics. Models differ.

All of your comments above are part of the practices many now implement in chute modeling. We use ROCKY. Would you like to try it free of charge for a month. Two months if you report back to the forum on your observations. ■

Hi Lynn,

If you get a copy of the book "Granular Media" you will start to realise that the ore variability as far as size and moisture content makes the measurement of "stickiness" unrealistic. The actual flow complexity of granular mechanics is an enormous challenge and it is only when we are dealing with reasonably uniform material sizes that we can simplify the mathematics to the point that we can create accurate flow models. As you state in your recent white paper once we have material size variations we also have to deal with material segregation and the fact that larger particles will have a far different trajectory than smaller particles and then if you add water the variations are even more extreme. The common factors when we are looking at cohesive ores is having a significant proportion of particles of a size of less than 200 micron and water. The finer the ore or greater proportion of say nano fines the more cohesive the ore for a given moisture content. It may well be possible to develop some form of measurement that will allow us to compare the relative "stickiness" as we vary water content and particle size and this could be useful but I do not believe we can quantify this measurement into a useful number that can then be inputted into some sort of flow equation. The reason I say this is that our work has shown that even material where you say have all the particles in the ore at -6mm you will get an enormous separation between particles that are 6mm and particles that are say 20 micron so we end up with a very complex dynamic. The consequence is we have relied totally on empirical work to create the flow models that allow us to design transfers focusing on the extremes rather than the average. It has allowed us to find some rather unique properties that we can now use providing we maintain a dynamic flow environment. We have started talking to a University in regard to taking this work and creating a different flow logic than what has traditionally been used and from this hopefully we may create something that works a lot better on cohesive ores but this is a fair way off.

In so far as your comments on using basic common sense in a transfer design (no 90 degree or less corners) etc to avoid build-up, that is a given and we agree

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

Thanks for the offer, but my real point is that the relative low capital cost of chutes bears no relation to their process importance and the design attention merited. Great strides have been made in modelling but, at the end of the day, design boils down to employing the relevant parameter values. ■

Hi Lyn,

Your comments on low capital cost of transfer chutes when compared to their importance is no better emphasised than in the iron ore industry which has moved towards mining much more variable ores, ores that contain a high proportion of fines and water. The consequence is that 30 years ago transfers were not even considered that important, today they are the single largest maintenance issue across the Pilbara iron ore province in WA and the single largest constraint to fix plant capacity due to their reliability issues. There is no simple mathematical solution today, if there was we would not have the problems that are so evident.

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

Originally Posted by Colin Benjamin

Hi Lynn,

If you get a copy of the book "Granular Media" you will start to realise that the ore variability as far as size and moisture content makes the measurement of "stickiness" unrealistic. The actual flow complexity of granular mechanics is an enormous challenge and it is only when we are dealing with reasonably uniform material sizes that we can simplify the mathematics to the point that we can create accurate flow models. As you state in your recent white paper once we have material size variations we also have to deal with material segregation and the fact that larger particles will have a far different trajectory than smaller particles and then if you add water the variations are even more extreme. The common factors when we are looking at cohesive ores is having a significant proportion of particles of a size of less than 200 micron and water. The finer the ore or greater proportion of say nano fines the more cohesive the ore for a given moisture content. It may well be possible to develop some form of measurement that will allow us to compare the relative "stickiness" as we vary water content and particle size and this could be useful but I do not believe we can quantify this measurement into a useful number that can then be inputted into some sort of flow equation. The reason I say this is that our work has shown that even material where you say have all the particles in the ore at -6mm you will get an enormous separation between particles that are 6mm and particles that are say 20 micron so we end up with a very complex dynamic. The consequence is we have relied totally on empirical work to create the flow models that allow us to design transfers focusing on the extremes rather than the average. It has allowed us to find some rather unique properties that we can now use providing we maintain a dynamic flow environment. We have started talking to a University in regard to taking this work and creating a different flow logic than what has traditionally been used and from this hopefully we may create something that works a lot better on cohesive ores but this is a fair way off.

In so far as your comments on using basic common sense in a transfer design (no 90 degree or less corners) etc to avoid build-up, that is a given and we agree

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com

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I succumbed to your emphasis on superior knowledge buried in books. I bought the "Granular Media" book based on your holy grail guideline and find we already incorporate most of what they describe in their text. Our main criticism is their world is more 2-dimensional.

Further we have not met a material we cannot calibrate and therefore model. I am sure they exist. When we meet them, refinement will follow. ROCKY is built to be refined to the latest standard which can be measured. At present, all ores tested have been modeled, by ROCKY, with success. Somewhat like Dr. Tim Donohue described. ■

Originally Posted by lukazi

Hi Colin,

Sorry for getting back to the topic after a while.

I understand that your company had a lot of success with the design of transfers. I also read that one of your most successful projects was chute design at FMG port. Would you have any data available of the blockage frequency with their older chutes and with the ones you designed?

Many thanks

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Lukazi:

I make you an offer. Send me a image and drawing of the plugging (dwg. or Inventor or Solidworks) of your most troubling chute. I will model it for free and demonstrate/simulate its present action. After observing we can model it with appropriate accuracy, we will undertake a solution. If we find one, we will so note.

CDI has not met a chute, with sticky material, we cannot correct the flow regime. No need to build models of failed systems. We can send you a procedure to obtain the sticky parameters where you can build in the shop and test for material properties.

Lawrence Nordell

Conveyor Dynamics, Inc.

360-671-2200 ■

Dear Lukazi,

CDI is a design firm who practices chute designs for new green field and problems with existing installations.

We have client ore calibration methods to guide our simulation modeling.

The easiest program is to fix known blockage.

Your question on statistics of time lost due to blockage has not been our concern. I agree it is of interest to clients with the problem and we should garner such data. However, our primary concern and charge is to quickly fix the problem.

Good Luck in your pursuit. ■

Dear Lukazi,

We have no record of our chutes continuing to block after design modifications. We have experience with chutes blocking when a contractor did not follow the design and did their own invention that did not work. Client comes to us with a claim of poor design. Drawings show we are not at fault and when corrected to our design, problem is solved. ■