Flash of Genius: And Other True Stories of Invention,   ISBN:9780312535728

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1. Mechanical shovels load the rock into hauling trucks and delivered to the primary crusher.
2. The primary crusher possesses steel jaws and crushes the rock into fragments ¾ of an inch.
3. The rock falls on a conveyor and transported to a silo outside the mill.
4. The low-grade rock is dumped into one of four heaps with the largest heap being flatten to 30 ft in height and 100 feet in length.
5. Heap leaching. Irrigation sprinklers spray the rubble with weak cyanide. The cyanide combines with the gold. Over the next three weeks the cyanide and Gold will percolate through the pile, leaching the gold out of the rocks. The Cyanide and Gold combination is call pregnant solution. The cyanide solution reaches a sloping rubber pad at the bottom of the heap and run into sluices at the edges, to a pond, and from the pond into the mill.
6. Heap leaching cost Cordex, $5 to process a ton of ore mean a grade as low as .0125 (.0125 ounces per ton) can be leached profitably. The process is effective with invisible gold.

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I love books like these that show how regular people can create amazing gadgets. I grew up seeing my Dad fashion problem solving devices from junk in the basement. I can't get enough of books like these. I already bought and read Gadget Nation Gadget Nation: A Journey Through the Eccentric World of Invention a similar book, but a little funnier because it showcased quirky gadgets. I ended up buying a couple from the store at http://GadgetNation.net/store. Hope that helps. ;)