Gypsum Properties
We had lab testing done on ROM gypsum at a mine in Nova Scotia. The materials engineers recommended that an internal friction angle of 50-60 degrees was appropriate until a plane of failure formed, then 40 degrees as sliding occurred. For wall friction, an angle of 30 - 35 degrees was recommended for AR steel walls.
We assume that the above is for dry conditions, and that moisture could significantly affect these criteria.
Bruce Higgins ■
Re: Material Properties Of Gypsum Rock
Thanks for the info Bruce.
Do you know the size of the product that was tested?
My understanding is that product tested in the lab is usually smaller in size as it is difficult to test larger size product. For larger size material I would imagine that these values would be less.
J. Pope ■
Material Trajectory Off Truck Dump
Dear J.
Standard trajectory calculations will not give good results. The nature of the trajectory is more dependent on the onset of shear. This cannot be calculated without knowing the dynamic behavior of the particle flow stream and the aggregate of particle shapes.
This said, we can model the event using DEM. See our website.
We will do this once for no charge to also gain an understanding of another application in the field of granular mechanics.
If interested, contact the undersigned.
Lawrence Nordell
Conveyor Dynamics, Inc.
www.conveyor-dynamics.com ■
Material Properties of Gypsum Rock
I am trying to calculate the material trajectory of gypsum rock from mining trucks. In order to calculate the velocity I need to know the internal friction of the gypsum and the dynamic wall friction angle. I do not have these material properties for this specific material but am looking for information that may provide a range of data. The angle of repose is approximately 45 degrees with top size around 48" and down to fines.
Any information or ideas would be much appreciated.
J. Pope ■