"It is believed that the Large Hadron Collider (LHC) could produce one of these micro black holes, but this is highly unlikely due to the relatively small size of the collider. (It is theorized that to create a micro black hole with currently-available materials would require a circular accelerator roughly 1000 light years in diameter). Although the Standard Model of particle physics predicts that LHC energies are far too low to create black holes, some extensions of the Standard Model posit the existence of extra spatial dimensions, in which it would be possible to create micro black holes at the LHC[2][3][4] at a rate on the order of one per second. According to the standard calculations these are harmless because they would quickly decay by Hawking radiation."
Quoted from the wikipedia section "Micro_Black_Holes." Most important part bolded for emphasis.