If you ever decide to stop doing that, please destroy the skillet or drill holes in it so nobody else will inadvertently restore it and start cooking with it and get lead poisoning. (Yes it happens.)The only cast iron piece I currently own is a small Wal-Mart special frying pan. It worked excellent for a lead smelting pot for pouring jig heads and split shot.
Usually skillets used for lead smelting will have white residue stuck to the cooking surface.