[zxcvbob]

Pick out all the weights that are stamped "Zn" or "Fe". Only fill your melter about 1/3 full, and heat it up kind of slow, and stir it occasionally. When the stuff melts, stir in some sawdust or some cooking grease and let it smoke, then skim out the clips. Turn it off just until the lead hardens, then add a bunch more weights and fire it up again. (if you are absolutely certain the weights are dry, you can skip the "wait until if just hardens" step)

It'll go a lot faster this time because of the residual heat in the clean lead at the bottom of the pot, and you can turn the fire up higher because you don't have to worry about any zinc weights trapped at the bottom of the pot.

Try to keep in under 700 degrees. You just need to heat past the liquidus point (when the slushiness goes away)

I have a 6 pound chunk of zinked lead that I haven't thrown away yet, cuz I can't throw anything out (you'd think I was a Great Depression baby.) I've heard that below about .5%, zinc is a good hardener, so I'm thinking about casting some half-dollar sized "coin" ingots from it and using 1 or 2 per 20# pot of soft lead. Of course 1 might be too much and then I'll really have a mess...