I got a three-legged, rounded bottom, black cast iron Dutch oven-type thing at an estate sale and I would like to know how old it is. The lid has No. 3 on it along with the D.R. SPERRY BATANIA, IL imprint. There also is a small curved rectangle imprint on the lid but I can't decipher any letters or words. The lid is concave like for campfire cooking. The handle on the lid is attached with a screw and a square nut. The cauldron has a wire handle and 9BB imprinted on the bottom where the three little legs are. Would appreciate any help in dating this piece.