Battery plates are sintered, not cast and contain liquid inside them. When the liquid flashes to steam as can happen when a plate is melted it can and does throw molten alloy many feet. Another problem is the alloy contains cadmium, arsenic, selenium, and some toxic stuff, too.
In short, NO !, do not try to salvage battery lead.
Of course, we are going to hear from the "It's ok, I done it." crowd shortly on.
And they probably did, just like the guy who cleans his guns without checking to see if they're unloaded. He'll get away with it, too. For a while.
They're your eyes, your skin, and your health. Do what you wish.
Three Hawks