I'm surprised that rocks melt at such a low temp. Steel just starts to have pockets of it melt at that temp, I would have thought a natural ceramic would be more. I can't imagine getting spatter on myself.
It really depends on the rock composition. It wasn't provided in the video. Pyrometer readings weren't shown either so it's hard to say. One thing's for sure though; it was hot enough to burn your leg off!
Imagine if they had a sufficient furnace and mass to create lava bombs that could be launched a few hundred meters in the air!
Wow had no idea you could reach that point with induction. It's something I kinda want to mess around with one of these days. 60kw though, might need a hydro upgrade for that one.

And to win the lotto to pay for that bill.
Induction can go much higher but it's probably more efficient from operating cost perspective to use a gas fired burner. And much easier for a backyard experimenter. 100# propane cylinders are cheap and easy to transport and will provide plenty of fuel for hours long runs. Whether you're heating up scrap to displacement castings of ant colonies or casting parts for engines, it'll do just fine.
If one did have three phase power on premise with a 100kVA or larger transformer to supply the furnace operating costs for four hours wouldn't break the bank. Unless the bank is really small.

60kWx4h = 240kWh. At higher rates (net $0.18/unit) that's $43.20 for a furnace run. A 250mbh burner (output) can run off a 20# BBQ type tank but it won't run that long due to pressure issues. They ice up very quickly under such flow. That's the nice thing about electric - it just works.
Did you change your avatar??
I don't think so.