Yeah, sand isn't really the question, its heating it with an induction plate that concerns me, the induction plate heats the metal container on top of it with the use of an induction current, the vessel heats up and so do the contents as a result, however I have not tried this with solid matter like sand. Just looking for any potential "gotcha" on this idea.
The reason I like the induction plate is that it is low profile, digital and very accurate in terms of dialing in temps. And about a third the cost of a heating mantle.