Looking For Help - Safe Paint Removal



I'm looking for some confirmation on what I'm trying to do, I have a large cast iron grate that was used as a vent for a historic business building that I got from an auction in town. They say it's cast iron but it's rusted as hell on the unpainted side and another side has some thick brown paint on it.

My main question is: Can I simply burn the grate at a hot enough temperature for a long enough time to get rid of the paint on it or is there some method that will make sure it's safe to use?

Also, is there a way I can confirm it's cast iron? I just don't want to take the chance of it being some kind of metal that's actually not safe to use.