A rock box is normally used when you want material on material contact to prevent chute wear at the impact zone. If segregation or different products are run in the same chute a rock box is not practicle and a better chute design is required to collect and direct the flow properly to the receiving system.

Having a very accurate trajectory of the material is key the to location of the rock box shelf. The size of the chute is based on system capacity and lump size.

My company specializes in transfer chute design and bulk flow analysis (virtual prototyping) and would be pleased to provide you with a quote to design your chute or to simulate the flow of material from a design by others to ensure the design will do what you expect it to do before you build the chute. This saves countless hours of "tweaking" an incorrectly designed chute after the installation.

Please contact me below if you are interested. ■

Granular Dynamics, International (GDI) has perfected DEM based rock degradation technology, surface wear measurements, and gas dynamics coupled to DEM. The code is trademarked ROCKY.

ROCKY can also classify lateral forces due to off-center loading and necessary power to accelerate the material being transfered onto the receiving belt.

TUNRA laboratory, a part of Newcastle University, recently studied the degradation by dropping products from multiple heights, with multiple drops of the same ore particle to characterize each stage of degradation. From these statisitics GDI perfected the JKMRC (Queensland University, Austalia) laboratory measure of rock breakage based on their T-10 properties. The JKMRC data closely aligned with the GDI rock breakage model.

Based on the above, GDI analyzed a standardized rockbox vs. a curved hood and spoon. The rockbox created 5 times as many fines as the curved hood and spoon. The product was a coal product known to TUNRA and used in their drop height experiments. This work will be published in the up comming DEM conference in Denver, Colorado this August by Dr. Alexander Potapov and Dr. Tim Donahue from TUNRA.

Any rock group can be studied, if the user is willing to do the drop test work or hire TUNRA to perform the same. TUNRA used about 50 samples to create the data for the T-10 comminution model.

Anyone wishing to become informed, please send to the undersigned.

Conveyor Dynamics, Inc. (CDI) does consult on chute design as well. For those that do a lot of chute designs, there is economy in doing the work with a competent DEM code such as ROCKY. CDI has designed many hundreds of chutes, bins, belt, apron, screw, and vibrating feeders with ROCKY. The code can also assist with vibrating screen designs, and many other types of granular flow. The code is capable of mutiple cores past 64 (Windows limit), many millions of granular particles (>6 million to date), and very complex geometries to millions of facets. ■

I can offer you physical dynamic scale modelling (DSM), DEM modelling, or a combination of both to evaluate transfer chute design and help you visualise the flow path.

Different methods have their strengths and weaknesses.

It sounds to me that perhaps at this stage you need a fairly basic view of the flow that your design might produce. Its best to start there and then you can refine the design as needs be. ■

The basics for designing a rock box type transfer is covered in our book "The Transfer Chute Design Manual" and does not require any elaborate evaluation using DEM. The process is simple and straight forward. As far as whether it will deliver a decent outcome, if the delivery belt speed is under 2 m/s and you have free flowing material. it is a good design concept. It should not be used for cohesive or adhesive materials and if material degradation is an issue then maybe there are better alternatives. Hood and spoon chutes will reduce the degradation but will be subject to wear but also have their limits as far as outcomes. The Cascade chute is a better alternative if you have free flowing abrasive rocks to deal with. The most famous of these is the WEBA chute. We will publish in the near term a very different chute concept again based on an empirical design approach that has proven far more accurate than the approach followed by those proponents of DEM but this will need to wait a little while

Cheers

Colin Benjamin

Gulf Conveyor Systems P/L

www:conveyorsystemstechnology.com ■

Originally Posted by Colin Benjamin

The basics for designing a rock box type transfer is covered in our book "The Transfer Chute Design Manual" and does not require any elaborate evaluation using DEM. The process is simple and straight forward. As far as whether it will deliver a decent outcome, if the delivery belt speed is under 2 m/s and you have free flowing material. it is a good design concept. It should not be used for cohesive or adhesive materials and if material degradation is an issue then maybe there are better alternatives. Hood and spoon chutes will reduce the degradation but will be subject to wear but also have their limits as far as outcomes. The Cascade chute is a better alternative if you have free flowing abrasive rocks to deal with. The most famous of these is the WEBA chute. We will publish in the near term a very different chute concept again based on an empirical design approach that has proven far more accurate than the approach followed by those proponents of DEM but this will need to wait a little while

Cheers

Colin Benjamin

Gulf Conveyor Systems P/L

www:conveyorsystemstechnology.com

Nothing in this realm can be completely quantified. No amount of ore charactersation can be translated directly in to end results for transfer chute behaviour. Those with any experience will realise that. And those that haven't will wonder what to do about the ultrafines analysis. Others will gaze at the clouds and spout nonsense. Their predecessors will perhaps cling with affection to the Coulombic rhetoric that has ruled the roost for so many lost years.

What Colin says is right. Empirical methods, in combination with experience and site feedback are powerful design aids.

It is both interesting and rewarding to see it evolve. ■

Dear Bulkoholics,

I need some book or olher think about discharge chute. Can we help me? I'll going to travel for training operate a program of chute analysis,

but I don't know details about chute analysis.

Please, send to address: keninhapx@gmail.com

Thanks!

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We all have our experiences, preferences and biases on chute design and tools of the trade. Some simple comments when evaluating the tools are:

1. Historical experience and complexity of the chutes in question

2. Degradation of product is quantifyable by simple tests and measurements

3. ■

Dear Nivea Pacheco,

Please go back 4 posts from this one and read:

Colin Benjamin

Registered User

The basics for designing a rock box type transfer is covered in our book "The Transfer Chute Design Manual"

You find more details here:

https://forum.bulk-online.com/showthread.php?21113



You may also want to study this material:

https://who.bulk-online.com/tagdiscu...fer-chute.html

An do not forget to check how Google sees Transfer Chute Design on this Portal:

http://www.google.de/search?client=s...ulk-online.com

http://www.google.de/search?q=transf...=lnms&tbm=isch

Reinhard Wohlbier

Administrator ■

3. Ability to analyze all forms of particle geometry (round and non-round) and, within a finer particle set, demonstrate accuracy with laboratory testing of flow properties

4. Method of analysis vetted by independent academic studies that verify technique and results

5. Method of analysis is reasonably fast and accurate -

6. Instructions on design procedures are clear and comprehensive as set forth in a users manual

7. Analysis can be performed by reasonably competent designer with basic engineering skills and drafting tools

8. Analysis can handle dry and wet products with rheology modeling capability that mimics laboratory testing

9. Analysis can digest large and small flow regimes

10. Modeling tool can evaluate moving surfaces such as flop gates, starting and stopping of flow field

11. Vibration analysis, if required

12. Dust analysis, if required

13. Comminution properties are quantifiable by others which have historical data base and industry respected protocol for breakage properties

14. Wear model is quantifiable for liners and belt surfaces

15. Model can capture forces on all chute, bin, gates, surfaces which then allows the meshed force field applied, to these surfaces, to be analyzed by FEA (ANSYS, ABACUS, ...) that render stresses and deformation of all surfaces

16. How large a rock size (small to large) can the model handle: comprehensive models can easily handle 20:1 size ratio (i.e. 200 mm to 10 mm) without large execution time to solve.

17. Create geometries with known CAD packages that you can build parametric models to import into: AutoCAD, Solidworks,

18. Know what the future may hold: elastic, plastic, viscoelastic, elasto-plastic, ....modeling capabilities

19. Purchase a DEM code that fits your budget and that can grow as you grow

It should be noted, there are two or more methods to determine product comminution, degradation or breakage:

a) Capture and analyze force interaction spectra that can be later quantified by laboratory test which shear attrition and impact fracture are definable

b) Model properties that result in physical breakage of particle sets

Test drive a DEM model before purchasing to see if it fit your future. How many particles can it handle ( millions if required), what size ratio can it efficiently handle in time ( hours, days, weeks, months) and provide the comprehension on moisture (adhesion, cohesion), agglomeration, deglomeration, fracture, dust, .... and other factors as noted above.

We know of five competing commercial DEM codes: ROCKY (Granular Dynamics International), Chute Analyst (Overland Conveyor), Newton (AC TEK), EDEM (DEM Solutions), Chute Maven (Hustrulid Technologies), Helix DEM (Helix Technologies). GO to the websites and witness differences. Obtain a demonstration package to compare results. See claims and obtain references that you can call and discuss efficacy. Best to talk to those that have compared all viable DEM Codes. See support and evaluate update path. ■

Hello!

I need to know some details about cohesive and adhesion coefficients to calculate and simulate a chute at software Bulk Flow Analyst. Someone makes this calculation at this software and knows these parameters?

■

Some interesting reading for you.

Do some research on Hauser Ratio and Carr's Index.

http://www.ckit.co.za/secure/conveyo...i1-paper04.htm

Attachments

129-136_cleary (PDF)

■

We will publish a paper in September that will be very relevant to your question Nivia. What I will say now is that I seriously question the accuracy of any published figures giving the so called adhesive or cohesive values. The complexity of the flow dynamics in transfer chutes is such that computational flow models such as DEM are at their very best approximations and of absolutely no use to any designer when applied to cohesive or adhesive ores. We have been working in this area now for 30 years and it has taken us all this time to work through these complexities to come up with a workable and logical design approach. We also now have actual working examples that clearly demonstrate the accuracy of our approach, in fact the results have been compelling.

All the best

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

Thank you Gary for an interesting attachment. Somebody had done quite a bit of homework.

Colin says "...absolutely no use to any designer when applied to cohesive or adhesive ores." and I agree if we omit "absolutely". The software is just emerging from infancy, perhaps reaching adolescence and definitely deserves a chance to mature. At present, as said, cohesive forces seem to be the stumbling block. A little water is a bad thing. Plenty of water aspires to pulp.

My last job was to audit a nickel project in Indonesia. Wet ore would not come clean out of tipper truck bodies and the truck suppliers advised against large scale trucking. Across the bay the Chinese were using tipper transport with some success. I witnessed both sides of the coin, can I say Nickel? It was true. So there are at least 2 ore bodies with different properties. How can you design for such situations where the very chute geometry changes in accordance with degrees of accretion and incoming water content? The client continued with an overland conveying proposal, secure in the knowledge that it wouldn't work.

Would DEM simulation adequately solve those cases where material builds up: constricts chute geometry and either blocks the chute or periodically detaches from the chute wall and significantly thumps the surroundings? I do not have DEM expertise so I have no answer, but perhaps others have.

To get back to the original question all I can say is that rock boxes would not have helped my Client at all. ■

John, I will argue that not only is DEM in its infancy but some of the basic premises on which the computational models are derived are wrong when it comes to cohesive or adhesive ores. Most of the literature on this subject suggests that the flow model for transfer chutes should be based on dense granular flow wherein we can show that flow in transfer chutes can be either dense granular flow or quasi static flow dependent on the design and nuances of the design. If this is the case which flow model do you use in your computation. The mathematics is extremely complex when it comes to cohesive materials and frankly it is impossible to create a satisfactory mathematical model without a myriad of extreme assumptions that basically renders the flow model useless in all but very basic design work.

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

As I stated in an earlier posting we would publish more information about the work we have been doing on transfer chute design. I suggest for those interested you read the paper in the technical articles section of the Forum along with Peter Donecker's comments and additions, click here:

https://forum.bulk-online.com/showth...r-chute-design

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

Hello,

It is difficult to describe in the forum the complicated (acrobatic) design procedure for the subject matter to derive optimum result. However, basic principles are as below:

1) One has to plot material discharge trajectory from pulley.

2) Then he decides suitable location for impact shelf (stone box).

3) From there the material may have free fall and sliding motion or alternatively sliding motion only, etc., in any number of combinations.

4) The designer calculates the material flow velocity in each segment of the path, step by step, in accordance with the increase / decrease in kinetic energy.

5) The designer concludes the chute arrangement by trial and error such that the material velocity at chute outlet, has desired magnitude and direction. The velocity magnitude and direction needs to be suitable to the equipment being fed (whether conveyor, crusher, etc.). The conclusion should also result into proper position of the equipment and economy of the arrangement In totality (including chute and particularly transfer house).

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 ■