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If you’ve never seen this you really should to understand how bad this can go. https://www.bbc.com/future/article/20150402-the-worst-place-on-earth https://www

If you’ve never seen this you really should to understand how bad this can go. https://www.bbc.com/future/article/20150402-the-worst-place-on-earth https://www.bbc.com/future/article/20150402-the-worst-place-...

londons_explore 3y ago
I've been to some of these 'toxic lakes'. Usually they consist of a few things in large quantities that are easy to neutralize - eg. sulphuric or nitric acid. And thats mixed in with small amounts of something that is natural yet toxic - eg. Mercury, lead, arsenic, etc. The whole lot is typically in the form of a slurry with solids and lots of water. It has to be kept wet, or the toxic solids will turn into dust and blow everywhere. It can't be allowed to get too wet, or it will overflow the containment pond. As far as I can see, there is no real solution - while the acids can be neutralized, the heavy metals can't be locked back into solid rock form - at least not at the scale of these ponds. I suspect the best thing to do (apart from not mining at all) is to just make ponds as big as possible and let them settle for as many decades as possible, and eventually they'll turn back into mudstone-like rock.
- danaris 3y ago
  Now, this may be naïve or uninformed, but... Shouldn't it be possible to take that slurry and deliberately dry it out much faster, possibly even including a step that separates the products to some extent for separate processing or storage? If it were being dried out in a sealed processing facility, rather than a pond open to the air (and wildlife), the toxic dust wouldn't be a problem—indeed, it would be the end goal. Turn it to dust, compress the dust into something you can seal in a jar or whatever and then store the sealed jar. Or potentially even sell it; I bet some of these toxic byproducts would actually be something someone else wants for their own industrial processes. Obviously even if it's possible, this isn't done because it would be more expensive—but if we, say, were more concerned with health and safety than profits, couldn't this be much less time-consuming and risky to the local water table than just letting it sit for decades or centuries?
  - londons_explore 3y ago
    Yes, you could dry it (for an immense energy cost). But now you have a toxic powder. And it's harder to store that powder than it was in slurry form. The massive volume is by far the biggest problem, compared to the (relatively low) toxicity.
  - MisterTea 3y ago
    > Now, this may be naïve or uninformed, but... Like, that costs money and stuff.
    - danaris 3y ago
      And if I thought that profitability of these companies was The Most Important Thing, then that would matter to me. As it stands, I think that companies shouldn't be allowed to offload negative externalities onto the public and the world at large. I think they should be required to clean up their own messes.
      - londons_explore 3y ago
        Even if money is no object, there aren't many environmentally friendly solutions to acidic mine tailings ponds. Most treatments require huge amounts of energy, which itself isn't very environmentally friendly.
- scythe 3y ago
  With the exception of arsenic, most of these metals can be effectively immobilized as the sulfides. That's how they naturally occur, and the sulfides are so inert that early life never encountered the metal ions or adapted to them — which is probably why they are so toxic! The sulfides of lead, mercury, cadmium and copper are all very stable and insoluble. So the solution may be quite simple: once the lake pH is adjusted to be not too acidic, pumping hydrogen sulfide into it should entrain any heavy metals in their natural form. This is a dangerous process, though, because hydrogen sulfide is an extremely toxic gas.
0xDEF 3y ago
The health of the global climate is so much more important than the local environments damaged by critical mineral mining. I'm sure a few progressive European countries like my own will volunteer to clean up as long as we start mining yesterday and start building more wind turbines, solar panels, and mass energy storage batteries.

londons_explore 3y ago

I've been to some of these 'toxic lakes'. Usually they consist of a few things in large quantities that are easy to neutralize - eg. sulphuric or nitric acid. And thats mixed in with small amounts of something that is natural yet toxic - eg. Mercury, lead, arsenic, etc. The whole lot is typically in the form of a slurry with solids and lots of water. It has to be kept wet, or the toxic solids will turn into dust and blow everywhere. It can't be allowed to get too wet, or it will overflow the containment pond. As far as I can see, there is no real solution - while the acids can be neutralized, the heavy metals can't be locked back into solid rock form - at least not at the scale of these ponds. I suspect the best thing to do (apart from not mining at all) is to just make ponds as big as possible and let them settle for as many decades as possible, and eventually they'll turn back into mudstone-like rock.

danaris 3y ago
Now, this may be naïve or uninformed, but... Shouldn't it be possible to take that slurry and deliberately dry it out much faster, possibly even including a step that separates the products to some extent for separate processing or storage? If it were being dried out in a sealed processing facility, rather than a pond open to the air (and wildlife), the toxic dust wouldn't be a problem—indeed, it would be the end goal. Turn it to dust, compress the dust into something you can seal in a jar or whatever and then store the sealed jar. Or potentially even sell it; I bet some of these toxic byproducts would actually be something someone else wants for their own industrial processes. Obviously even if it's possible, this isn't done because it would be more expensive—but if we, say, were more concerned with health and safety than profits, couldn't this be much less time-consuming and risky to the local water table than just letting it sit for decades or centuries?
- londons_explore 3y ago
  Yes, you could dry it (for an immense energy cost). But now you have a toxic powder. And it's harder to store that powder than it was in slurry form. The massive volume is by far the biggest problem, compared to the (relatively low) toxicity.
- MisterTea 3y ago
  > Now, this may be naïve or uninformed, but... Like, that costs money and stuff.
  - danaris 3y ago
    And if I thought that profitability of these companies was The Most Important Thing, then that would matter to me. As it stands, I think that companies shouldn't be allowed to offload negative externalities onto the public and the world at large. I think they should be required to clean up their own messes.
    - londons_explore 3y ago
      Even if money is no object, there aren't many environmentally friendly solutions to acidic mine tailings ponds. Most treatments require huge amounts of energy, which itself isn't very environmentally friendly.
scythe 3y ago
With the exception of arsenic, most of these metals can be effectively immobilized as the sulfides. That's how they naturally occur, and the sulfides are so inert that early life never encountered the metal ions or adapted to them — which is probably why they are so toxic! The sulfides of lead, mercury, cadmium and copper are all very stable and insoluble. So the solution may be quite simple: once the lake pH is adjusted to be not too acidic, pumping hydrogen sulfide into it should entrain any heavy metals in their natural form. This is a dangerous process, though, because hydrogen sulfide is an extremely toxic gas.

0xDEF 3y ago

The health of the global climate is so much more important than the local environments damaged by critical mineral mining. I'm sure a few progressive European countries like my own will volunteer to clean up as long as we start mining yesterday and start building more wind turbines, solar panels, and mass energy storage batteries.