Blending often implies selective extraction for downstream mixing. Portal scrapers usually work a full pile face which compromises selective extraction. Bridge mounted bucket wheels are more able to extract selectively when they traverse the pile face.

BUT...Do not confine blending examinations to an ability to extract from a stockpile or bunker selectively. Stockpile construction is also important to blending. If the machine cannot get to a few fines at the top of a coarse pile then the blending needs to be reconsidered.

It all depends on what you are stocking and what you need to do with it. In this business want is not the same as need. ■