[lpetrich]

Discussion of this issue may or may not be out of place here, but we had some discussion of rare earths here not long ago. We've also had some discussion of "peak phosphate".

I wish to note that most of the chemical elements that we use are mined. We look for deposits where they are relatively concentrated and then mine them. This raises the question of what we do when the ores run out. It's much like fossil fuels.

But there are sources that I haven't seen much discussion of, except in very limited contexts. Garbage, ordinary rock, and seawater. For garbage, I've seen some discussion of e-waste, but not much more. For ordinary rock and seawater, hardly any. Ordinary rocks are metal silicates, and I've found only a few things on getting the metals out. Seawater should be straightforward to refine. Boil off the water and let its salt content precipitate. The more abundant constituents will precipitate first, leaving the less abundant ones in the remaining water. But I haven't found much on that either.

Some references on mining ordinary rock, mainly in reference to living on Mars:
Aluminum Extraction From Clays - Open Source Ecology
Metal Refining - Open Source Ecology
Bringing Mars into the Iron Age - NASA Science
Homesteading the planets - NASA Science

Related ones:
From Garbage to Glass: Mining Landfills for New Materials | Architect Magazine | Technology, Architects, Recycled Materials, Green Materials, Salvaged Materials, Peter Jones, Ivan Cornejo, Colorado School of Mines, Colorado
The Oil Drum: Europe | Mining the Oceans: Can We Extract Minerals from Seawater?
Abundances of the elements (data page) - Wikipedia

These processes likely require a lot of energy, especially if one wants to recover the rarer elements.

But I think that if renewable sources can be made good enough, then they can supply the necessary energy. Thus, renewable energy may be able to solve not only our energy problems, but also our resource problems.

[GHung]

What you're talking about is using widely-dispersed low-concentration energy sources to extract and refine widely-dispersed low-concentration resources in order to try and support economies built, and run on, using concentrated cheap-to-extract energy sources to extract and refine concentrated resources. Simple physics get in the way. It's not whether or not it can be done, but if it can be done economically at a rate and scale sufficient to maintain industrial rates of consumption.

Scraping the bottom of the garbage can won't save the industrial age. The math is pretty simple.

[ROCKMAN]

I: As Ghung points out it's all based upon economics. For much of what you speak the tech has been available of many decades. It's just the question of costs. Forget the cheap stuff that can be extracted from sea water: there are billions of ounces of gold dissolved in sea water and extraction methods are well known. You just have to wait until the price of gold gets high enough to make it worthwhile. Essentially no different then what we just experienced with the shale boom in the US: the exact same dynamic.

Which is why there will always be an endless stream of snake oil salesmen pitching their latest tech "breakthrough". Such as "free energy" from water, etc. LOL. I personally like the idea of beaming microwave energy from solar panels mounted on space platforms hundreds of miles in width...beam me up...I mean sign me up, Scotty.

[vtsnowedin]

Ghung has it right. The one exception might be mining American style landfills built from the 70s to the turn of the century. There you have an "Ore" source that contains a higher percentage of copper, aluminum, iron, glass, and plastic which is higher than any natural rock formation. They will certainly be mined at some point in the future when other supplies become scarce or expensive. A landfill in Egypt on the other hand would yield a lot less as material going into it is already thoroughly picked over by scavengers.
Where recycling is practical and efficient it is already being done, witness the scrap metal and junk yard industries.

[PrestonSturges]

I've always thought someone should look into the possibility of capturing phosphorous etc from seawater via ion exchange chromatography media.

[PrestonSturges]

Hasn't that already been tried with gold?

Like anything else it's a question of cost versus more polluting practices where the public is forced to deal with the externalized costs.

Recovering gold from thiosulfate leach pulps via ion exchange
Michael J. Nicol, Glen O’Malley
Increasing environmental and occupational safety concerns about the use of cyanide in gold processing has increased interest in more acceptable alternative lixiviants, the most promising of which is thiosulfate. However, the thiosulfate process lacks a proven inpulp method of recovering the dissolved gold because activated carbon is not effective for the absorption of the gold-thiosulfate complex. This paper describes work aimed at evaluating the effectiveness of commercially available anion exchange resins for the recovery of gold from thiosulfate leach liquors and pulps

[lpetrich]

What you're talking about is using widely-dispersed low-concentration energy sources to extract and refine widely-dispersed low-concentration resources in order to try and support economies built, and run on, using concentrated cheap-to-extract energy sources to extract and refine concentrated resources. Simple physics get in the way. It's not whether or not it can be done, but if it can be done economically at a rate and scale sufficient to maintain industrial rates of consumption.

I don't share GHung's pessimism about "widely-dispersed low-concentration energy sources." Most recently, wind and solar electricity generation have gotten close to economic parity with fossil fuels (Report: Wind, Solar Costs Approach Parity With Fossil Fuels | Valley News, among other recent articles). I will concede that they still have a way to go, like energy storage and production of combustible fuels, but there is a lot of work being done on both of these, and I'm sure that they also will someday become competitive with fossil fuels.

That being said, I fully concede that ordinary-rock mining and seawater mining are doubtful prospects. Some widely-used elements are not very common in either ordinary rocks or seawater.

[GHung]

What you're talking about is using widely-dispersed low-concentration energy sources to extract and refine widely-dispersed low-concentration resources in order to try and support economies built, and run on, using concentrated cheap-to-extract energy sources to extract and refine concentrated resources. Simple physics get in the way. It's not whether or not it can be done, but if it can be done economically at a rate and scale sufficient to maintain industrial rates of consumption.

I don't share GHung's pessimism about "widely-dispersed low-concentration energy sources." Most recently, wind and solar electricity generation have gotten close to economic parity with fossil fuels (Report: Wind, Solar Costs Approach Parity With Fossil Fuels | Valley News, among other recent articles). I will concede that they still have a way to go, like energy storage and production of combustible fuels, but there is a lot of work being done on both of these, and I'm sure that they also will someday become competitive with fossil fuels.

That being said, I fully concede that ordinary-rock mining and seawater mining are doubtful prospects. Some widely-used elements are not very common in either ordinary rocks or seawater.

lpetrich; I suggest you have a problem with scale, energy, and entropy. In short, you either can't do the math, or ignore it.

[lpetrich]

(me on wind and solar becoming economically viable)

lpetrich; I suggest you have a problem with scale, energy, and entropy. In short, you either can't do the math, or ignore it.

That does not account for the emerging economic viability of wind and solar.

BTW, I've been perusing the abundance figures in Abundances of the elements (data page) - Wikipedia, and some of the numbers are rather interesting. It has numbers for the Earth's bulk crust, its upper crust, and its oceans, and also for Solar-System averages. For instance in the Earth's crust, such recently-prominent elements as neodymium and samarium (for permanent magnets) and gallium (for LED's) are about as abundant in our planet's crust as long-used elements like copper. Also, aluminum, magnesium, and iron are *very* common there, not far behind silicon. In the Earth's oceans, phosphorus and iron are *very* rare, despite their importance to organisms' biochemistry. However, another biologically-important element, sulfur, is not much less common than chlorine, the most common dissolved element.