from a old thread on a similar subject, Jay did a few calculations.
Not to criticize, but these numbers don't look right. For starters, the atom-sized black-hole would have a mass of around 10^-15 kg, not 10^15 kg.
10^-15 kg is about the same mass as 1000 billion hydrogen atoms, which sounds right if you consider the micro black-hole has no vacuum between its nucleus and electron cloud like atoms do (that vacuum would be all filled with collapsed atoms). "minus" is but a dash, but here it's dash that translates into 30 orders of magnitudes !
By comparison, the mass of the Earth is 6*10^24 kg.
Also, I don't think it's meaningful to calculate the damage a black hole can do based solely on how much matter per second its surface area allows it to gobble. In case you haven't noticed, demolition explosives do a lot more damage than the dump trucks which carry out the debris. Black holes "in the wild" sort of rearrange matter around them into an accretion disk and THEN suck it down. If we had a black hole on Earth, it would probably break the planet into bits quickly, and then it really wouldn't matter how much time it would take for it to swallow the bits.
But let's assume Jay's assumptions are correct and a micro black-hole won't eat up much of our planet... that'd forgetting the LHC is estimated to generate one black-hole per second. I think we all know the damage difference between a muzzle-loaded single-shot rifle and a belt-fed machine gun.
I can't be bothered enough to whip-up Matlab, but I'm pretty sure everyone talking about the LHC's micro black-holes today are talking out of their @$$es. Need I remind you how much of particle physics is based on theories and indirect evidence ? Or what the Heisenberg principle of uncertainty means ? It's not like we've ever put a black-hole sample under the microscope... actually that's why we need to build and USE machines like the LHC.
So, like I said, let's switch on that bad boy and see what happens
and tell me beforehand so I can plug my ears, ya know, just in case.
Nefastor