This guy is building a 74 foot sailboat. He collected 17,000 pounds of wheel weights in 2009 and built a a wood fired pot to reduce the WW to ingots. He didn't sort anything, as is evidenced in the video where valve stems are burning off. His requirements are very different from ours so zinc in the mix won't hurt his outcome. He's very creative and every tool he makes is thought out very well.
https://www.youtube.com/watch?v=Dl-N-2Jgkr8