These mini black holes everyone is freaking out about happen every day when cosmic rays hit particles on the earth/in the earth's atmosphere. The world hasn't disappeared yet, so I think we're safe with these particle accelerators.
I went through the calculations to see what it would take to create a catastrophic black hole for a science project a few years ago. At the time I did the calculations for the Fermilab accelerator, but we compared our calculations to the estimated capacities of the LHC and it was still many orders of magnitude away from being even close to something that could possibly be dangerous.