Removing silver flake from steel wool

[Ikimasen]

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.)

 

[Borek]

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.

 

[Dadface]

Work out your costs first.Is there enough silver to make this financially worthwhile?

 

[Borek]

Good point - but muriatic acid is quite cheap.

 

[Ikimasen]

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.

 

[Borek]

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?

Yes, filtering should do the trick. I would start neutralizing the solution, at least partially. For example with sodium carbonate or bicarbonate.

 

[lightarrow]

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.

 

[Borek]

Is this 'find the most complicated way of silver separation' contest?

 

[lightarrow]

Is this 'find the most complicated way of silver separation' contest?

The first answerers are in advantage. The last have to say more complicated things