It's entirely possible to set up a workshop as effectively doing arbitrarily complex multi-stage processing...
Iron enough to make a nail,
Lime enough to paint a wall,
Water enough to drown a dog,
Sulphur enough to stop the fleas,
Potash enough to wash a shirt,
Gold enough to buy a bean,
Silver enough to coat a pin,
Lead enough to ballast a bird,
Phosphor enough to light the town,
Poison enough to kill a cow...
...I just wouldn't consider the tricky art of gunpowder-making as likely even
fictionally abstracted to block-raw in and magic-powder out. Even if there's precedent (kitchens, e.g., with that mysterious mincing stage), it seems to me to be against the game philosophy (though of course not moddability, by any given Sylvester McMonkey McBean who wishes) to have a new and potentially game-changing product so simple, unfussed and streamlined.
No, I don't expect it to actually be at risk of exploding (though, as a balancing mechanic, it would be like miasma for a butchers, only more cave-in-like... even if general grinding, even intensive flour-grinding could also be mysteriously unsusceptible). But, when it comes to the percussive pummeling of expired equines, I think I've now fully expressed my thoughts on this, to be enjoyed or ignored.