I used to work at a fertilizer company... We had 3 different types of potash... Each varying in density from 63 to 95 pounds per cubic foot. The really fine stuff will be much heavier than what we had... And if it gets wet can set up some, probably even worse for fines. Every time we had a pneumatic bring us a load we just had them bottom dump it necause it either took FOREVER to blow it off or it got plugged up. I dont have any personal experience running pneumatic... But my experience being around them with potash is that it is a very slow product to blow off.