As said, I think Enviro lead is a trade name. There are others like it by firms that do the same.

I think the plates in a battery are pure lead and pure zinc. I think they will separate the two metals when batteries are recycled.

There is a firm in Derbyshire that has been doing this for years. They recycle everything including he battery casing. From what it says everything they reclaim goes back into making new batteries so the lead will be separate from the zinc.