Recently started at a new property and they have the old style tiled surrounds. The ones that get all moldy and gross. I've got a bunch that need a lot of work, including replacing the rotting drywall behind it with something more modern.

I can't put surrounds in, it has to stay tile and a full remodel isn't in the budget. So just repairing tile is what I have to teach myself, the only other guy doesn't know how to do it and I'm the lead so I gotta figure it out.

At this point I've tried a couple smaller repairs and they look decent but the issue I'm having is removing the old grout and mortar from the tiles so I can reuse them. It's time consuming and I wasn't trying too hard since I figured it'll just get grouted over anyways. But then the tiles don't fit right which makes them not sit right when you put them back in.

I've tried a sanding stone from Lowe's, the manual grout saws and a multitool grout remover blade. They all kinda work but it doesn't really speed it up much. I've tried scraping and prying with my glazier bar which seems to be the most effective but also risks damaging the tiles of which I don't have much to spare.

I'm wondering if I can use a bench grinder, maybe that will speed up the process. Does anyone here have to rebuild tile surrounds and wanna share their experience?