Hi there Shakee..

Without wishing to appear rude, if you have to ask such a question, I suggest you get someone who has done it before to design your downhill conveyor for you..

I say this because these conveyors can be quite tricky, and you have to analyse them dynamically for all load cases for starting and stopping.

Only then can you re-arrange the hardware to best serve the conveyor.

We have done quite a lot of them, but they still take me a lot of time to optimise them to eliminate all possible operational risks.

Cheers

LSL Tekpro ■

Shakee,

If you are designing a down hill conveyor system, let us take a look at your requirements. We designed a DSI Gently Pressed Snake for a gold mine in Mexico. It was to carry material down the side of a mountain directly to the leach pads at a 37 degree angle. DSI was awarded the contract, but unfortunatley, the DSI GPS was abandoned because of the geology of the mountain. The reports showed the stability of the mountain off by 1 degree so they abandonded the idea. Instead DSI was commissioned to install an overland conveyor with horizontal curves and a series of trippers to replace the use of an agglomerating drum in the prior system.

I've attached a press release about this particular project.

Please contact DSI and allow us to review the requirements of your project. We look forward to hearing from you.

Best Regards,

Amy Duncan

www.dossantosintl.com

aduncan@dossantosintl.com

Attachments

los filos complete (PDF)

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Hello,

As for allowable inclination, there is no distinction whether conveyor is up-incline or down-incline. So you can use allowable inclination as per published literature.

It is understood that while choosing the inclination and drive type, the designer will take care of material stability on belt during acceleration / deceleration i.e. starting / stopping.

- For incline up conveyor, the start up acceleration should not be very sharp / large, such that material slides back on belt.

- For incline down conveyor (decline conveyor), the stoppage deceleration should not be very sharp / large, such that material will slide forward on belt.

For sufficiently decline conveyor (which is regenerative or which can be classified as a regenerative conveyor by conveying friction coefficient 0.012), the conveyor becomes economical with good performance when drive unit is at tail end.

Regards,

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

Who is Who: Ishwar G Mulani

https://who.bulk-online.com/profile/...-g-mulani.html

https://who.bulk-online.com/discussi...-g-mulani.html ■

A downhill slope criteria is not simple as noted by Graham. There are many factors that influence the design criteria. Here are a few:

1. Shape of rock - round, prills with slight oblongation, natural crushed rock,

2. Size distribution of rock

3. Speed of conveyor

4. Braking control method - deceleration rate and jerk action - hydraulic circuit speed and PID controller details.

5. Degree of ore particle-to-particle confined stress

6. Trough shape (affects confined stress) - 25 degree, 35; 45 degree, equal length rolls, shorted center roll

7. Alternative belt crossectional shapes - 3 roll, 4 roll, 5 roll, and six roll cross-sections

8. Moisture -surface %

9. Cohesiveness & Elasticity of contacts - aids in binding

10........

Conveyor Dynamics, Inc. (CDI) has designed 100's of downhill systems starting back in 1975. We hold the record for the largest tonnage downhill at C=12,500 t/h, among highest speeds > 7 m/s, highest belt strength, most advanced fail-safe brake control system.

Having said the above, I am in doubt Mr.Shakee is in search of a downhill conveyor expert. ■

Larry makes a good point regarding the complexity of the material stability analysis. The detailed DEM analysis is relatively new and the conveying angles listed by CEMA (Conveyor Equipment Manufacturers Association) are not based on DEM. They are empirical, inconsistent and very limited in the materials for which there is a recommendation. In practice many use a downhill incline angle which is 3 to 5 degrees less than the recommended angle for up hill conveyors. This is to reflect the control (or lack of control) over the conveyor's operation. Normal operating control can limit the stopping time to limit accelerations but emergency stops and power outages, for safety reasons, cause the engagement of the brakes which apply more severe stopping forces.

Regarding the best location of the drive (or drives) it is merely a matter of looking at the tension distributions throughout the total operating range.

Joe Dos Santos ■

A long, extensive questionnaire will not cover everything because you really need to know everything about the conveying path, the material, the rate and the customer's objectives and constraints. This really means as many drawings as it takes to fully define the path and the topography along that path. You must know everything about the material (bulk density, size, nature ie rounded angular, etc, moisture, etc). You must develop the required design rate. Once all available information is in hand, except for a very simplistic profile, you must run many analyses to determine the best driving and take-up arrangements and the the required tension controls. Only in very simplistic cases are these obvious.

You must hire a good consultant. You may want to consider Dos Santos International. ■