It is already being done. Dealing with old piles of trash is somewhat dangerous (all sorts of volatile gasses build up there) but once you get around this you can burn the thrash (releasing quite a bit of energy) and go through the ashes later. The ash can be used for various purposes, such as construction, but needs to be sorted by grain size first. While going through the ashes you do indeed encounter precious metals. I recently read about a company that performs this sorting as a service. They are not paid for the work directly, but get to keep the gold (and possibly other metals?) they find. Apparently you can expect to find a gram or two of gold in a tonne of ash.

That doesn't sound like much? That's less than 100USD per tonne (approx $40/g current gold price)

Is there much other valuable stuff in the ash to make the venture worthwhile?

I dug up the original article for some fact checking, and it seems my previous post has a few mistakes in it. There are "grams" of silver and gold (each or together? The article does not specify.) and "kilograms" of copper in a tonne of ashes. Other metals are also extracted, but their amount or value is not specified.

It further turns out that there is a monetary payment for the service, but it is low because of the valuable metals. The article also tells that the machine can sort around 100000 tonnes of ashes annually.

According to this article, a good open-pit gold mine has deposits of about two grams per tonne.

http://www.mining.com/web/making-the-grade-understanding-exp...

I'm interested! I've done small-scale precious metal reclamation, also silver castings and home forgings. Basically that makes me an expert ;)

As someone with no knowledge of this, how do you do small-scale precious metal reclamation and how did you get into home smithing?

Here is a link to a popular scientist YouTuber who has done significant work in this area

https://www.youtube.com/playlist?list=PLKhDkilF5o69PqPy-oMCC...

Well worth the watch

I built a forge a few years ago with a bucket, plaster of paris, some quartz sand, some iron pipe and a blow dryer. Then I started hammering on steel when it turned red.

Metal reclamation is just chemistry so youtube and grainger are all you really need.