Now classically a digestion in nitric and cementation with copper will remove the lead from the silver but that requires a substantial chemical usage. So I went to my bookshelf and was reading in Silver by Butts & Coxe (that's really the authors names so don't ban me for this) that at the Oroya silver refinery they charge the molten metal from their thum cells with sodium nitrate to remove traces of lead and bismuth. I would prefer to remove it before it goes into a cell.
Has anyone here ever tried this method? I have access to a reverberatory furnace and plan on trying this method to clean up the bars before making them into anodes but I'm curious if anyone has tried this.