Question: Is it possible to "pump" a powder the same way liquids can be pumped?

If so, what are the challenges? If not, what are some alternatives?

Answer: 
There is a key difference between liquids and powders:

* Liquids have internal cohesion and can be sucked, but with a powder, you need a carrying medium.
* The internal friction in a powder will usually be far higher than in a liquid.

In practice, this means that to pump a powder, you inject air or another gas as fluidizing agent. The pumped or blown air carries the powder, like a dust-storm within the pipe.
We have dry cement bulkers truck running on local roads, feeding dry cement to mixer factory where it is turned into wet mixed cement. Pump air into the truck to 'blow' cement out.

This [video](http://youtube.com/watch?v=p74BAe-OYq0) shows cement and sand are 'blow' by air. Powder (cement/sand) are placed in closed container. Air blow in and powder come out on, says, 2 to 3 inch diameter, tubing. Powder can be transferred in construction site, at horizontal and vertical distance of tens of meters. You can see the blue air-compressor in the video. Here is a similar [video](http://youtube.com/watch?v=p74BAe-OYq0).