Refix slate slips around wood burner?

Hi,

The top slate slip has come loose above our inset wood burning stove. What would be the best stuff to use to refix it in place.

I'm guessing I will have to try to remove some of the existing cement from the back of the slip so that it sits at the same level as the other slips. Hammer and chisel don't seem sensible, what a bout the ubiquitous angle grinder?

Small chisel and lots of small tapping so as not to disturb the other tiles if any Go get some proper fire brick mortar mix from a specialist company and ask their advice

Slate is quite hard to fix. Go to a tile/flooring shop and askfor advice there regarding a fixative.. Cement alone won't do it.