Below is an infographic giving information on recycling of an iPhone. It is interesting to see how much many rare minerals are used to produce an iPhone. The infographic also give valuable information on what is done with recycled iPhones.
iPhone 3G is the most recycled phone in US valued at USD 45/- per phone. iPhone 4 fetches the highest recycle value at US8 178/- per phone. 90% of the second hand iPhones are refurbished and sold while only 10% of them are recycled.
You should also check out an infographic on what Minerals is your iPhone made of.
Source : 911metallurgist