Material Properties of Gypsum Rock

(not verified)
Posted in: , on 23. Jan. 2003 - 02:53

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

Bruce Higgins
(not verified)

Gypsum Properties

Posted on 3. Feb. 2003 - 03:50

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

(not verified)

Re: Material Properties Of Gypsum Rock

Posted on 3. Feb. 2003 - 06:55

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

Posted on 16. Apr. 2003 - 09:57

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.

Lawrence Nordell Conveyor Dynamics, Inc. website, email & phone contacts: phone: USA 360-671-2200 fax: USA 360-671-8450