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: 
While pumping powders as a mix with swiftly moving gas is viable, one of frequently used alternatives for both powders and granular materials is [Archimedes' Screw](http://en.wikipedia.org/wiki/Archimedes%27_screw).

![enter image description here](https://i.stack.imgur.com/KE01J.gif)

Essentially, a helix in a diagonal pipe making the material "pour/roll" upwards the curve, allowing lifting it a long distance. This solution is frequently used in farming equipment for transporting grain or granulates. While it doesn't provide "pressure" for moving it through inert pipes, a "pipeline" of such screws can go a long way, and while it restricts transport angle, it provides a viable alternative especially for heavier materials where extreme air flows would be required to move them.
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).