Good catch, zxcvbob. As you pointed out awhile back in a post about using old automotive batteries:
They've changed the formula quite a bit in the last few years. Used to be, I think the plates were made with pure lead. Then they added antimony (which is still OK.) Now they harden the lead with calcium. I don't know if calcium lead is usable or not, but if it gets mixed with antimony lead, the calcium and antimony will react to form an intermetallic compound that separates out in the dross, and reacts with water to form stibine gas -- it's related to cyanide but more deadly.
Also there's really not much lead in a battery. It's mostly lead oxide paste and sulphate. That *can* be smelted back into lead, but it takes lots of high heat and it releases sulphurous fumes.
Just cut the top posts off and keep them, and recycle the rest of the battery.-zxcvbob
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