Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Removing silver flake from steel wool

  1. Sep 29, 2010 #1
    I have a practical question. I work in the radiography department of an industrial contractor and we've found some old recovery buckets used to recover the silver from old film fixer. Essentially you have a bucket of steel wool that the fixer (with silver precipitate) passes through, which traps the silver flakes in the fixer. Now I have what you might call a "bucket of crud" that is a mix of wet steel wool with silver flakes in it which, so far, no one wants to buy. How can I separate the silver from the steel wool without losing any silver so it can then be sold? (who cares about the steel wool.)
     
  2. jcsd
  3. Sep 29, 2010 #2

    Borek

    User Avatar

    Staff: Mentor

    Dissolve the iron in hydrochloric acid. Concentrated is sometimes sold under the name of muriatic acid. Be careful - it is a nasty, corrosive stuff. Gloves and glasses are minimum, and you better add it outside, as it requires a good ventilation. Once diluted it is not that scary.
     
  4. Sep 29, 2010 #3
    Work out your costs first.Is there enough silver to make this financially worthwhile?
     
  5. Sep 29, 2010 #4

    Borek

    User Avatar

    Staff: Mentor

    Good point - but muriatic acid is quite cheap.
     
  6. Sep 30, 2010 #5
    So the hydrochloric acid will destroy the iron but leave the silver behind, with nothing left to do but strain it out of the acid? It should be cost effective, though I could buy silver concentration test strips to make absolutely certain, but really there should be a pretty good amount of silver in there.
     
  7. Sep 30, 2010 #6

    Borek

    User Avatar

    Staff: Mentor

    Yes, filtering should do the trick. I would start neutralizing the solution, at least partially. For example with sodium carbonate or bicarbonate.
     
  8. Sep 30, 2010 #7
    If the silver flakes are enough, in absolute sense and compared to the steel wool, another possibility is melting: silver melts at ~ 962°C while steel or iron oxides melts at much higher temperature.

    If one has a lot of mercury and have a fume hood, it could also remove silver making an amalgam with Hg and then remove this by boiling. Quite complicated, however.
     
  9. Sep 30, 2010 #8

    Borek

    User Avatar

    Staff: Mentor

    Is this 'find the most complicated way of silver separation' contest?
     
  10. Oct 1, 2010 #9
    The first answerers are in advantage. The last have to say more complicated things :smile:
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook