Seeing that we are steadily depleting our planet’s sourcesof raw materials, I wonder why we cannot profitably mine the old dumps. For example, you can profitably mine copper ores that are less than 0.1% copper, and iron ore is now mined that is of even lower concentration.
Old landfills contain junked cars, plumbing, and scrap brass and bronze. In addition, there is probably a lot of lead and aluminum in these old dumps.
So, could they be mined profitably? How would one go about obtaining mining rights to a landfill?
And, what unpleasant things are likely to turn up in an old dump (I can picture me unearthing the remains of the late Jimmy Hoffa, for example!).
Is mining dumps a good idea?
The problem witt mining landfills is that they are usually being used. Around here, landfills are turned into golf courses or housing developments. That makes them a little difficult to mine.
I’m pretty sure we have a fairly efficient car recycling industry in this country. I saw a documentary on them a couple of weeks ago. Cars are often taken to “Pick-A-Part” yards where people can scrounge them for parts. Other cars are dismantled and the parts sold that way. After a certain amount of time, the most efficient junkyards crush the cars regardless of if they have more usable parts on them. This allows more room for new wrecks coming in. Once the cars are crushed/shredded, they are formed into blocks and melted down to be used again.
I saw a lot of junked cars on my recent long drive, so not all junkyards operate the same way; but I think that generally you are not going to find many cars in landfills.
You have a point about aluminum and other metals, but I think it would not be economically feasible to “mine” them. There might be something to recovering methane gas, though. (They might already do this. I don’t know.)
Well, first, copper mining isn’t terribly expensive, nor is copper a scarce resource.
Second, mining process are well-adapted to dealing with the typical minerals and waste matter/metals found in natural ore deposits. Dealing with the huge amount of various metals from the alloys in a dump is not going to be very easy to separate out, and some new methods would have to be moved into large scale.
Aluminium is a separate issue, since processing of aluminum ore into aluminium metal is quite energy intensive, whereas recycling of it can be done economically. It is often said in the industry that aluminum is the only thing currently recycled in the US which makes economic sense at this time.
There are a bewildering array of Federal, State, and local EPA and environmental restrictions to use of landfills. Whether it’s siting issues, health and safety of the workers (OSHA), emissions of HAPs released whilst processing - it takes a bit of doing sometimes.
In certain areas large landfills have been tapped for methane to power small IC engines for power. Typically, when you include the total capital, legal, permitting, and O&M costs these barely go above break-even. Some cases where the regulatory restrictions have been streamlined and there has been substantial cooperation from the authorities have been quite a bit more successful.
Nasty things you find in landfills are going to include such items as mercury, lead, cadmium, antimony, selenium, tin, arsenic, and an entire zoo full of carcinogenic compounds and toxic substances.
The only nitpick I have is that steel is also routinely recycled…we just don’t call it recycling because the steel industry does it voluntarily and makes a profit on it.
I think landfill mining will have to wait a few more years before it becomes profitable…I’m imagining a fleet of insectlike scavenging robots that are programmed to gather one particular material each.
If you have an abandoned dump accessable to you, you can “mine” it for old discarded items that are antiques now, such as glass bottles.
When nanotechnology finally makes its debut, all waste dumps will be mined for molecular disassembly. The human race will eventually realize the insane extravagance of throwing away a single item. Small self-replicating molecular sized disassembly nano-robots will cheaply convert entire landfills into valuable raw materials.
The biggest problem is making sure the disassembly nano-bots are properly contained. Some current projections have found that if such self replicating recycling nanotechnology got loose from controlled conditions, they could convert the entire face of the earth into grey slime over a couple of weeks.
Landfills are being mined as we speak. And for the Most Valuable Stuff In The Universe: Dirt!
No kidding. A NYC area landfill is making money by digging up the dirt that was used to cover the new trash each day and selling it to still running landfills. (The old landfill can cover the trash it exposes with a single layer. The rules state it has to be covered by night. It doesn’t specify how deep it can be before being covered. So operating landfills use a lot of dirt.)
As for re-using the more obviously useful materials, it’s the old boot-strap problem. No one builds plants to extract stuff since no one is recovery huge amounts of raw trash, no one extracts stuff since there is no plant to send it to. But one day it will start small and grow from there.
Weird… I have been saying almost exactly these words to people for a while now; did we both read the same SF story (I can’t remember reading one on this subject), or do great minds really think alike?
My husband used to work in the garbage industry. He says that there is talk of digging up old landfills to feed incinerators in the future. Modern incinerators–now called waste-to-energy facilities–have magnets to pull out metal after everything else has been reduced to ash. It would then be much simpler to sort.
Assuming regulations had been adhered to, digging into recent landfills should not be a problem because the methane should have been vented out. But it could be a problem in older, pre-reg landfillls.
The story I’m referring to is:
Assemblers of Infinity
by Kevin J. Anderson
There was a company in Massachusetts that attempted to do this in the Town of Fairhaven. BIOSAFE began mining the landfill then compressing the remaining material. It was expected to add 10 years to the life of the old landfill.
A local group of paranoids, fearful that BIOSAFE was going to contaminate more than it cleaned (the landfill being only a few hundred yards from the Middle School) got the project closed down.
Don’t know what’s up with BIOSAFE these days, but the Fairhaven, MA, landfill has been closed and capped, so now folks are dumping their trash in the woods, on conservation land, by the side of the road, etc.
However, the magnets only remove the ferromagnetic materials, and the process is still a low-efficiency one. Even austenitic (read: food grade) stainless steel isn’t really magnetic, and it would be left behind. Not that some metal is all that bad - the WTE furnaces are designed to handle quite a bit, and the molten metal is captured as slag. The main problem is in processing the fuel in the first place so it can burn well enough - I mean, you can dump trash on a travelling grate stoker furnace, or even a fluidized bed, but it sure burns much more efficiently if you can hog it or even fluff it prior.
The big thing is going to be mercury and other air toxics. There is mercury in an alarming array of compounds that are in landfills, and since it is pretty much certain there will be some tight mercury regulations within the next few years, this is going to put a damper on things.
Don’t some plants absorb and concentrate metals through their roots? Could you plant them on dumps and use them to collect minerals, or would they not go deep enough down or collect enough to be worthwhile?
it is possible to electromagnetically separate non-ferrous metal objects too; I’m unsure of the precise details, but it has something to do with Lenz’s law - inducing a current in a conductor, making it into a tiny electromagnet to which force can be applied - I remember seeing a practical application of this that sorted aluminium and steel cans from mixed garbage - because of the degree to which the different metals were deflected, they ended up in different bins.
Well, there’s a few things wrong with using plants like that. One is that many of the items are contained in a way that plants would not extract them - cadmium, lead and mercury in batteries; arsenic in industrial chemicals, zinc in galvinized metals, vanadium and chromium in baby food (j/k), etc. Then of course a typical “mature” landfill may be hundreds of feet deep, with many alternating layers of soil/trash/soil/trash, which would be hard to get down through.
I have seen a similar line of conversation used to justify not participating in community recycling. It went like this (quoting a neighbor):
(I don’t have an opinion on this - I just nodded blankly).
I don’t think the grey goo scenario has much going for it other than shock value. After all, do we expect our cars to fend for themselves in the wilderness, feeding on tree sap and performing complex self-repairs?
Also consider that nanoids have been around for nearly four billion years already, and they haven’t slimed the planet yet. The only difference is that we call the nanoids that already exist “bacteria”.
I don’t think it’s fair to use “current projections” as a synonym for “bad science fiction”.
And when Chronos agrees with you on a matter of science, you know you’re doing plenty right.
Anyway, my point is this: Even if we postulate highly biological nanites with the ability to self-repair and self-replicate, and even if we throw in the ability to evolve as a fringe benefit of the two previous abilities, we still can’t reasonably expect them to so profoundly out-evolve everything else to the degree where they become the only viable lifeform on the planet. This planet handled the Cambrian Explosion without becoming monospecies, and there was more evolution going on then than there’s ever been before or since. The fact is, life on this planet has been around far too long to be elbowed out by anything we can create.