I liked the piece by Owens because it had some data that I could get my molars round. I remember when I was a nipper watching a film about the gold rush in Klondike (or was it Ballarat, or Sutter's Mill?). Some whiskery and whiskey-whiffey Old Timer bursts into the Saloon crying "Thar's ounces to the ton". It struck me then as a poor return and a helluva lot of dirt that had to be processed for a thimbleful of gold. Gold is dense (19.3 g/cu.cm) so a couple of ounces would fill 3 ml. But ounces to the ton is HUGE, because the average sort of yield from open cast gold mines like the horrendous Serra Pelada is 1g per tonne - 1 part per million. Owens points out that mobile phones in contrast contain as much as 350g/tonne and you don't have to go to some yellow-fever infested jungle to get it. Other circuit-boards might have as much as 250 ppm.
- shred a 40ft shipping-containerful of old phones
- melt it down and boil it up at 1250oC
- the valuable metals (mainly copper) sink to the bottom while a noxious slag floats
- cool and grind metals to powder
- add sulphuric acid to dissolve the copper
- do some cleverer chemistry to separate the Au, Ag, Pt, Pd
- form into ingots
- process lead, cadmium and other byproducts from the slag
- buy yacht
You can't do better than send your old phone to The Jack and Jill Foundation who will recycle it efficiently. Like OU and RNLI, the J&JF is great because it helps people find the heroic in themselves.