I have an industry whose station is getting pretty overloaded. What I'd like to do is create a second station in the vicinity of the industry and use the stations exclusively for unloading of raw materials and loading of goods, respectively. Can it be done?
You can't manually control what stations collect what goods, it's not a function the game provides, but stations simply react to vehicles and will attempt to get any type of good that a vehicle tries to take, once a station starts to collect a good it will do so forever (until it is fully destroyed).
So, if you create two stations a ways apart, and then tell vehicles to only load at one, and only unload at the other:
Then it should work like you want:
See how Grutburg gathers passengers, and Grutburg Central doesn't?
You can indeed! Order your raw material trains to Unload and leave empty; order your finished goods trains to load. Yes, if you switch around and cease loading at the "producing" station then, for some time, goods will pile up there. But eventually that station's rating for that cargo will drop so low that this becomes a non-issue; production will go (more or less) only to the new pickup station.
Note that this isn't really necessary, though; you can just make a bigger station. Increase station spread and turn Allow joining stations not directly adjacent ON. Now you can build two physical stations joined into one logical station; just hold Ctrl while building. Use waypoints and via orders to direct traffic.
Also note that if your trains and platforms are different lengths, short trains will prefer the short platforms and long trains, the long ones. You can adjust the penalty for stopping at the "wrong length" platform if you're willing to edit
openttd.cfg by hand.