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Comment by londons_explore | Hacker News Reader

Sounds like a case of "it's too expensive to deal with this wastewater, so let's just put it in a big pond and hope the dam bursts and we can claim it was all a big accident"

Mining industries are especially famous for this - there are ponds of waste that are 70 years old, just waiting for their moment to escape...

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There's not much that can be done with it because essentially (not basically) it is acid. Phosphate mining uses sulfuric acid to extract the phosphates. These are large scale operations and produce a lot of water with a pH of 1.5-2. There's no comparable industrial process that can consume it as input. So it sits.

The gypsum stacks are the other waste byproduct. But it's less problematic because it doesn't flow, it just sits. The low level radiation prevents it's incorporation into commodity products such as gypsum wall board.

The byproducts get conflated because for convenience the radioactive gypsum waste from phosphate mining is used to contain the acidic sludge from phosphate mining. But it's the acidic sludge that is the fast acting ecological disaster. The gypsum will give you cancer of course, but as Joe Jackson sings everything gives you cancer. [1]

[1]: https://www.youtube.com/watch?v=WsQyru5ACmA

> There's not much that can be done with it because essentially (not basically) it is acid

Couldn't you neutralize it by (say) dumping in a bunch of baking soda? Or lye? (Hm, what actually happens if you mix sulfuric acid with lye? Do they neutralize each other, or turn into something even nastier than the sum of its parts? That'll teach me to blow off high school chemistry.)

There's far to much phosphate sludge for me to tackle. I don't have access to that much lye.

Anyway, far brighter minds than mine have been looking at for at least fifty years...Florida got serious about phosphate ecology and water quality in the 1970's. The gypsum stacks and sludge ponds exist because of water quality regulations not the good will of industry.

https://floridadep.gov/water/mining-mitigation/content/phosp...

> what actually happens if you mix sulfuric acid with lye

This reaction produces sodium sulfate (a salt) plus water and heat [1]. No idea if this is practical, though. Maybe it’s difficult to source sufficient quantities of some base to neutralize the acid.

[1] https://en.m.wikipedia.org/wiki/Sodium_sulfate#Chemical_indu...

There are alkaline wastes. Steelwork slag, power plant fly ash, residues from concrete production, and, the big one, what's left of bauxite after making aluminum. It's probably possible to build a plant to combine them and get some neutral-pH solid out. Still have a heavy metal problem, though.

Florida does not have steel production because it is distant from both coal and iron ore. Same for Aluminum.

It does have portland cement production due to the abundance of limestone near the surface. However, portland cement production is more or less local globally...or it's usually made relatively close to where used. Conversely Florida's phosphate industry is a major source globally. The scales are incomensurate.

Wouldn’t you get the same reaction as the baking soda and vinegar volcano experiment but on a huge scale?

Is this the kind of mines that produce phosphate for fertilizer?

Yes. That’s exactly what it is used for. I don’t recall the exact amounts, but the Tampa Bay area produces a sizable share of all phosphate in the world.

> because essentially (not basically) it is acid'

Haha, I see what you did there...lol. Touche, good sir.

The trick is to make sure there are a few leaks in each containment pond so the waste slowly leaks into the water table.

Then when it rains the volume of waste doesn't increase.

Do you have some more information about where those old ponds are located? Thanks!

Coal operations have slurry ponds where they store the sludge from washing the coal. And coal power plants have fly ash ponds which are bad for the environment. We’re shutting down the coal plants but these ponds will be around forever.

Here is a map of ash ponds from power plants

https://earthjustice.org/features/map-coal-ash-contaminated-...

Here’s a link to the slurry spill I lived through with no water for days

https://en.m.wikipedia.org/wiki/Martin_County_coal_slurry_sp...

And here’s some pictures of the “impoundments” https://earthobservatory.nasa.gov/images/8693/coal-sludge-im...

Edit to add this quote:

“ Although coal impoundments have a relatively low rate of failure, their extreme size—some hold more than a billion gallons of sludge—makes any breach potentially devastating.”

Another large spill that hardly anyone has heard of:

https://en.m.wikipedia.org/wiki/Kingston_Fossil_Plant_coal_f...

I am curious what you could do with all this. I was under the impression that ash could be composted pretty well. It is organic material after all. Or is the issue the other added chemicals?

Ash from wood may be compost-able, but I think the leftovers from burning coal can contain arsenic, mercury and lead among other things. There are also instances of the fly ash being radioactive. u/leetrout hints that they are from WV/EKY area, where hilly terrain can make stashing fly ash in slurry ponds less visible (but more susceptible to contaminating small streams undetected). Specifically in the eastern KY/OH regions, there massive impoundments <500 yards from navigable rivers (since barges transport to plants and water used in generation), so if they break, the sludge won't have far to travel to contaminate major waterways.

https://pubs.usgs.gov/fs/1997/fs163-97/FS-163-97.html - information regarding some of the byproducts.

Power plant and incinerator fly ash contains heavy metals and other poisonous substances so needs to be separated to prevent environment contamination.

But I guess you could turn it into bricks and isolate those instead or even use them as building materials in some form of infrastructure.

Ash is not organic material.

Thank you! Very interesting and frightening.

There is a gruesome death trap in Montana, https://www.hcn.org/issues/48.22/latest-thousands-of-snow-ge...

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