Re: Angle Of Repose
Here is one reference (refer (b)):
http://www.ckit.co.za/secure/conveyo...properties.htm
The angle of repose is generally used for "static" applications (i.e. stockpiles etc). Surcharge angle is used in "dynamic" applications, such as when being transported on a conveyor, to account for the observation the angle will generally reduce due to dynamic effects etc.
You mentioned "steep angled" conveying. The effects of loading on an inclination and or allowable inclination angle are other issues again and have been covered previously, refer here as a start (I guess the above has probably been disussed here before somewhere or other also):
https://forum.bulk-online.com/showthread.php?t=4338
Regards,
Lyle ■
Re: Angle Of Repose
Hi Lyle,
Many thanks for your valued information.
Attached is the cross section of sidewall conveyor belt, the dynamic repose angle is similar like the surcharge angle. From my experience, there may be some difference when the material are conveying by sidewall conveyor belt and general flat belt.
Waiting for your kind comments.
Best regards,
Luke
(cnplusu@gmail.com)
Attachments
sidewall conveying capacity (JPG)
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Re: Angle Of Repose
The fill geometry must be corrected for rock size and shape. Take the given thread geometry and apply a nominal rock size that is located where its center of gravity or geometry is just below the sidewall lip. In such a configuration, the material will build up behind this rock position, supported by the sidewall higher than your projected repose angle line. ■
Repose Angle
It has been said many times, but worth repeating. The angle of repose of a bulk material is dependent on both the manner and form of formation. The most common method of measuring an angle of repose is to form a conical pile by way of gentle pouring, but this only provides a consistant value with relatively coarse material, as the behaviour of fine powders tends to vary considerably according to their stste of dilatation. Where a material does form a consistent slope, the planar angle of repose tends to be slightly steeper than a poured cone and the inclination is steeper still for a drained cone repose angle, the differences arising from the diverging and converging flow regimes.
An inclined slat conveyor is usually filled dynamically and may suffer a small degree of vibration so it is difficult to advise, particularly without knowing the material being used. A simple test replicating the conditions in the feed system is suggested as the best means to secure a rough value. ■
Re: Angle Of Repose
Kind attn.: Luke,
In the previous information, I missed to mention following, for general clarity:
For bulk material handling equipment, the surcharge angle implies as stated and as understood by bulk material handling engineers.
In case of civil engineering, the retaining wall / surface holds the back filled bulk material. The back filled material sloping surface to horizontal is also called surcharge angle in civil engineering. The civil engineering surcharge angle can be positive or negative, as per planned filling. Obviously its maximum value will be like repose angle, positive or negative.
Regards,
Ishwar G Mulani.
Author of Book : Engineering Science and Application Design for Belt Conveyors.
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: parimul@pn2.vsnl.net.in ■
Surcharge Angle On Sloped Belts With Cleats & Flexible Sdewalls
Most of the visual diagrams are conceived in 2-Dimensions. In order to obtain a meaningful surcharge angle representation, it must be in 3-Dimensions.
If the Flex-wall Cleated belt is loaded from the side as opposed from an in-line postion, the surcharge angle may dominate the stable filling evaluation. Thus, defining the free-flowing rilling angle must be defined from the material's heap geometry on the Flex-wall belt.
A DEM model can clarify the result, given you believe in such tools. ■
Re: Angle Of Repose
Hi All,
I have come into this a bit late but the angle of repose of a material is also important in transfer chute design. We in fact put a significant section in our appendices on the subject. There are two good papers on the subject which we referenced, one by Tegzes in 2002 (Avalanche dynamics in wet granular materials. Physical Review letters, 89 094301-1-4) and another by Nowak in 2004 (Investigating the Angle of Repose and Maximum Stability of a Cohesive Granular Pile. BSC Thesis, Dept Physics, MIT)
Trust this helps
Col Benjamin
Gulf Conveyor Systems P/L
www.conveyorsystemstechnology.com ■
Re: Angle Of Repose
Kind attn.: Luke,
I would like to mention briefly the difference between repose angle and surcharge angle.
When material is dropped on a stationary surface, it will form the conical type of heap. The angle of the sloping face / line to the horizontal is repose angle. As an example, conveyor is discharging material on ground. Regarding the test for deciding repose angle please refer national standards which will specify specific conditions / modality to be followed while deciding the repose angle.
For the material resting on moving surface, the free standing surfaces will settle down (spread out) and its angle to the horizontal will be less than the repose angle. Such moving surface creates agitation (subtle vibration) and so the material tends to spread out. As an example, the material resting on moving belt will have free sides inclined at surcharge angle. The other example is material loaded into truck (in heap form). The free surface of material will have surcharge angle applicable to that application (situation). Regarding belt conveyor, the surcharge angle value is influenced by the belt speed, the sag being considered and how long it remains on the belt i.e. short conveyor or long conveyor. Well this is a finer aspect about the selection of the surcharge angle, beffitting to the application. The influence is limited to certain percentage reduction. The surcharge angle is for the material being carried by the moving surface and not when the material is dragged on the surface.
Regards,
Ishwar G Mulani.
Author of Book : Engineering Science and Application Design for Belt Conveyors.
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: parimul@pn2.vsnl.net.in ■
Angle of Repose
repose angle of differnent material and ration of static and dynamic repose angle?
Hello every one!
As mentioned in title. It is a puzzle quesion for me.
For steep angle bulk solid material conveying, the repose is angle is very important factor for the volume of bulk material conveying per hour.
If you have the data about the repose angle, please tell me, your kind work is highly arreciated!
By the way, I have a puzzle about the repose angle and slope angle, is the slope angle is the surchage angle, is there difference between surchange angle and repose angle, what is the most important for the bulk solid material conveying.
Many thanks & best regards,
Luke
cnplusu@gmail.com
(professional conveyor belt manufacture) ■