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.
In food process you can "pump" powder with vacuum, sugar works very well, and some other products need sometimes some technical adjustment (pression or open/close cycles valves) .
But water in the pipes is ban and last point it's only for small quantities and short distance 20meters max i think.