When I smelt , I use wood and the alloy melts first before the zinc . The Zinc just floats with the rest of the junk and just skim it off. I do all my smelting outside in a open fire , it works for me. Also that is how I was taught by my dad that use to work in the foundry many years ago before me. He taught me how to cast lead for sinkers and then I went to what I am doing now like the rest of you. In my bullet stop is where I do my berm mining when I change the board of only the alloy I find for when I have the dirt drop out. I save the rest for hard times. also for what is going on at the time.