If a micro black hole was dropped from the surface of the Earth, and that it was too small to absorb particles and eat the Earth, it would fall until emerging from the other side, then fall again and so on...

One would think that it may however collide with particles on the way, which would slow it down and make it ultimately settle in the center of the Earth.

How large would be such an effect, if existing at all? How long would a black hole take before settling depending on its mass?