• @Eheran
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    311 months ago

    Battery acid is extremely concentrated compared to that water. Iron can only precipitate if it is very dilute.

      • @Eheran
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        211 months ago

        Yes, that was measured somewhere in some amount. But not in this picture here for several reasons.

        If left for itself, that is the concentration it tends to go to since the water evaporates, leaving the H2SO4 behind.

        • Track_Shovel
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          111 months ago

          I’m not sure exactly what you’re getting at.

          Are you talking about the concentration of the water or the pH?

          The pH in AMD water is very low. Sub 3 values are not uncommon. If you’re talking about metal loading, that too can be relatively high, or extreme in some cases, and the impacts can be huge

          I’m not a geochemist, but have to have passable knowledge for my work. I know several colleagues who are geochems or water treatment geeks. I’m happy to reach out to them, if you would like to know more or get into the specifics.

          • @Eheran
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            011 months ago

            “sub 3” is nothing* compared to battery acid. Note that 1 pH more or less is a difference of 10x. here pH over concentration, note the graph ends at ~10 %, which is 1/3 of battery acid, but is already below pH 0.

            *Yes, technically every value below 3 is included in “sub 3”. But making an upper limit that is a more than 1’000x lower concentration is absurd.

            • Track_Shovel
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              211 months ago

              Alright, well I’ll concede that my estimation of pH for battery acid was off - they have it listed at 0.8. I’m accurate with the AMD levels though.

              It can get very bad though, like the iron mountain mine article I linked to, where it’s -3.6

              With the lower pHs, though, even those around 5, you get metal leaching which quickly becomes a large problem. On top of that, the wastes act as a massive source of both acidity and metals.

              • @Eheran
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                011 months ago

                I agree. It is just not THAT acidic. The pH will be above 3.5 to be more specific, which is the pH above which Fe3+ can precipitate. Check this pallet for details.

          • @Eheran
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            011 months ago

            “sub 3” is nothing* compared to battery acid. Note that ±1 pH is a difference of 10x. here pH over concentration, note the graph ends at ~10 %, which is 1/3 of battery acid, but is already below pH 0.

            *Yes, technically every value below 3 is included in “sub 3”. But making an upper limit that is a more than 1’000x lower concentration is absurd.