Author of Book: ‘Belt Feeder Design And Hopper Bin Silo’ Advisor / Consultant for Bulk Material Handling System & Issues. Conveyor design basis is ISO (thereby book is helpful to design conveyors as per national standards of most of the countries across world). Mulani Author of Book: ‘Engineering Science And Application Design For Belt Conveyors’. So inherently there will be some variation in the projected results. These will vary according to material condition (moisture content in the material or season, etc.). Also, repose angle or sluff angle are not very rigid figures. It is not for the purpose of sale and money payment.
You are estimating this quantity just for the purpose of knowing self reclaimable capacity. The material within these planes and hopper face is reclaimable material (live reclaimable material). From the reclaimed hopper edges draw the reclaiming planes at sluff angle. I think sluff angle is few degree more than repose angle. I think there is concept of sluff angle which is applicable to zone being reclaimed by collapsing stationary material. The material repose angle is in context of stockpiling or stacking operation and then resulting face angle to horizontal. However following information may be of use to you. Hello, I do not have a direct answer to your question.