What can they do? Practically nothing.
You didn't include the reality-check tag, so I'm going to assume that your source is right and stable black holes this size are possible.
Now, let's get into what they can do. As my main source, I used an article by CERN about the safety of LHC:
If stable microscopic black holes had no electric charge, their interactions with the Earth would be very weak. Those produced by cosmic rays would pass harmlessly through the Earth into space, whereas those produced by the LHC could remain on Earth. However, there are much larger and denser astronomical bodies than the Earth in the Universe. Black holes produced in cosmic-ray collisions with bodies such as neutron stars and white dwarf stars would be brought to rest. The continued existence of such dense bodies, as well as the Earth, rules out the possibility of the LHC producing any dangerous black holes.
In other words, as long as there are big objects in the universe (like Earth), no black holes that tiny are going to have any measurable effect on anything. It doesn't say it explicitly (maybe it does and I just didn't see it), but here's my explanation (bear in mind it might be completely wrong): It's just too little mass to have any gravitational pull. From what I see on Wikipedia, we're talking on the scale of micrograms. The earth, to get a 1g acceleration inward, has trillions of trillions of trillions of kilograms of mass. These black holes are far more affected by other objects than other objects affected by them.
There's my best guess, I hope it helps.
But while I'm at it, I might as well give you an idea for how you could massively scale up your particle accelerator. :)
This idea is from Death's End by Liu Cixin, the third book in the Three-Body Problem trilogy (if you haven't read it, I highly recommend it). In it, they construct a massive particle accelerator that rings the entire solar system. It's not enclosed, since one of the main reasons LHC and other accelerators are enclosed are to make a vacuum, which we already have in space, and each ring speeds up whatever it is and sends it shooting off to the next ring, which continues the process. Eventually, they let it go shooting away from the solar system at near lightspeed.
Don't know if that last bit is helpful, but I couldn't resist sharing what I think is one of the coolest gadgets I've seen in sci-fi.
EDIT: Okay, so you've now told me that these can be up to trillions of kilograms. So I'm going to go with the figure of a trillion for this next bit (also please note these are guesses, we don't actually have data on this):
If fired at a person, the person would be torn apart by tidal forces well outside their Roche limit (somehow it feels a bit wrong to apply that term to people, but black holes will do that). Within a couple centimeters of the black hole, there are hundreds of m/s^2 of acceleration, but a meter away it's pretty much negligible. So if they fire for your heart, you'll pretty much have your heart ripped out as the rest of your body stays intact.
If at a planet, here's where it gets a bit interesting. I'd expect it to be like Randall Munroe's Neutron Star Bullet scenario (which I can't find online, so I guess you need the book what-if to check it out): It'll fall toward the center of the planet, ripping its way through the same way it rips through a human's body. Once it's there, it'll kinda just... stay there.
At that point I see a couple options. (1) It'll rip everything within reach and then just stay right there in the middle of the planet chilling. (2) Pressure's too much or something so that whatever's outside keeps getting pulled in. The black hole grows significantly (okay, it grew significantly in number 1 too, but not as much) and keeps growing. It might possibly get large enough to cause serious problems for us unsuspecting humans above.
Again, this is guesswork. I've never seen a trillion kg black hole and I haven't had the chance to fire them at someone (though the first test subject might be an unsuspecting little brother). If you do happen to get data, please let me know! I'd be fascinated to see real stuff on this. But I guess that's not likely.