If lightning finds its way 2 the ground through shortest route possible then how could it have caused...?

Question

the Sago mine explosions? Can someone please explain how that make sense. Is there some kind of positive charge in mines that would attract lightning?

Answer 1

It does not.
Lightning will repeatedly hit a shorter tree in a forest of quite tall trees. It can also hit a tree, travel along the ground, through some people, and back into the ground. It can induce electrical currents elsewhere, as well.
Lightning is odd. It is a lot of current and can act quite strangely.

Answer 2

It could have hit ventilation fans or power wires going into the mine or tracks or just about anything.