350,000 phones were being into landfills every day in 2010. Fuck Apple's "thinnest phone ever", it's not worth the social cost. Dumb consumer vanity isn't the metric for optimization here.
iPhone users either get the battery replaced, sell the phone, or they trade the phone in. The trade in then gets sold again, and likely again after that. The iPhones resale value makes sure it is a long time before any are simply thrown in the trash.
These recycled phones either end up as refurbished phones in other markets, or are taken apart by their special robots down to the individual pieces, which are then recycled themselves.