Rockwool for floor sound insulation

Just looking for any feedback with regard to the use rock wool as a sound insulator.

Quite a lot of acoustic and structural noise travels between my flat and the flat below.

I have gotten a price quote to have rock wool pumped under my floorboards. I want to have it pumped as taking up all the floorboards would be too disruptive. The tradesman said pumping it would only require a couple of boards to be raised.

Has anyone had this done? Was it effective?
Thanks.