What? There's no such thing. There won't be any of the disk left over on the pan after your done grinding. And you clean the pan before seasoning it. And seasoning it will burn away/encapsulate anything left over. Stop being such a worry wart.

Yeah, it’s metal man. You’d be shocked at how many non food safe implements of destruction have touched that pan in its fabrication. Being metal, it’s easy to clean up to become food safe. A little oil, maybe a little salt scrub, a rinse, then low heat with some oil for a while to drive out the moisture and start the season.