Hello Dastgir,

The only time you would be able to take a representative slice of a stockpile end-cone would be at rake (harrows) angle set equal to, or smaller than, the angle-of-repose of the material. However at these shallow angles the material would not slide easily from the stockpile face.. if at all. (especially if moist)

 A rake angle equal to or greater than the natural angle of material slide (which is usually 8-12 degrees steeper than the angle-of-repose) is required to achieve reasonable reclaimation speeds (t/h). 

In the early days, we tried many different angles between the limits of adjustment of our reclaimer rake, with very little effect on the end-cone segregation effect.

I'm afraid that other methods such as end-cone removal, or proactive correctives manipulation are the only effective means of eliminating, or at least significantly reducing, the endcone segregation effect.

 Best Regards,

 Ted.