It makes perfect sense to me. But what I am wondering is how well it would function if the entire tube wasn't turning, but just the scoops at the bottom. Sure, there would be additional friction of the product against the sidewalls, but by acting as a fluid the product should still be able to rise almost as easily. This could reduce the need for moving parts drastically. It would essentially all be stationary like a spiral slide, but the scoops produce an inward pressure at the bottom that forces the material to go up the slide rather than down.,(reply>), You're adding a seal, at least one bearing, forcing the drive mechanism to be down near the product, etc etc. It's actually far simpler to do it this way, and allows the pickup to be easily immersed down in very fine material.