Once two metals are alloyed, they are molecularly one. There is no settling of the pure lead and floating of the lighter tin or zinc or Linotype
After doing some reading about alloys, I agree. Looks like separating the lead out of a lead/whatever alloy is like separating the white out of a cloud. I found a good description here:
An alloy is a mixture of fairly-pure chemical elements, which forms an impure substance that has the characteristics of a metal. Alloys are made by mixing two or more elements; at least one of which being a metal. This is usually called the primary metal or the base metal, and the name of this metal may also be the name of the alloy. The other constituents may or may not be metals but, when mixed with the molten base, they will be soluble, dissolving into the mixture.
The article seems to be saying that the atoms of the components of the alloy disperse themselves evenly within the mixture and it becomes homogeneous in consistency. Thats not to say that oxides of one or more of the components of the alloy don't form when heated in the presence of oxygen and become a non-soluble substance that will float to the top if it is less dense than the alloy.
Wrapping my mind around this, it looks to me like the oxides will form and float, since lead is denser, and you can skim them off...but you'll never get all of the "impurities" out of the mixture because the atoms of the metal you don't want are evenly distributed with the atoms of the metal you do want.
Am I understanding this correctly or have I missed something obvious? I'm no chemist, or metalurgist...
I guess I'll be casting some rifle bullets out of my alloy...you can never have too much ammo anyway.