Disposal of fixing solution

[Buzz]

Hi,

After precipitating the Silver from fixer using Zinc, what to do with the solution?
I am reading in various places that it it safe and ok just to pour down the drain?
Not so sure myself, thought i'd better ask.

Regards
Buzz

 

[9kuuby9]

here you go; http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?p=40800#p40800

 

[Buzz]

Thanks for that but not sure it's relevant to fixer solution.

The procedure that follows is for your acid waste only, it is not for cyanide or leaching type wastes, only the spent acids used to digest the metals you have refined.

I'm assuming here that finished fixer solution is a leaching type waste?

Buzz

 

[9kuuby9]

After cementation it basically is if I'm not wrong.

 

[goldsilverpro]

I'm not sure about the laws on this, so do your own research before doing anything.

If I understand correctly what Kodak says, most of the common photo chemicals are biodegradable and are legal to dump. I think that most fixer and bleach-fix would be in that category. However, that assumes the pure chemicals. If any heavy metals are dissolved, dumping would be illegal. When I worked in Texas, the legal silver limit was less than 1ppm. In your case, there is now little or no silver but there is a lot of zinc dissolved and that would make it illegal to dump. I would guess that removing the zinc might be a chore.

 

[Buzz]

Hi Chris,

but there is a lot of zinc dissolved and that would make it illegal to dump

That is what i was worried about.

Would the same apply if i used Manuels Sodium Sulphide method instead of the Zinc.
The solution should be heavy metal free (I think)

Alternatively, would adding Sulphuric acid to the solution and then dropping the Zinc out with an iron bar work?

Regards
Buzz

 

[9kuuby9]

Hi Chris,

but there is a lot of zinc dissolved and that would make it illegal to dump

That is what i was worried about.

Would the same apply if i used Manuels Sodium Sulphide method instead of the Zinc.
The solution should be heavy metal free (I think)

Alternatively, would adding Sulphuric acid to the solution and then dropping the Zinc out with an iron bar work?

Regards
Buzz

Read the post by 4metals in the given link; First of all iron does not cement zinc, and if you cement zinc with an other metal, the solution would still contain metals and would be still illegal to dispose of in the drainage.

 

[Buzz]

Hi,

I did read it but i don't believe that the procedure described in his post would be of any use with discarded fixer solution.

Here's what he said

The procedure that follows is for your acid waste only, it is not for cyanide or leaching type wastes, only the spent acids used to digest the metals you have refined.

Am i correct in assuming that discarded fixer solution is a leaching type waste?

First of all iron does not cement zinc

I mistakenly thought that iron would cement Zinc in an acidic solution.

So it would appear that using Sodium Sulphide to drop the Silver, as per Manuels advice, would be the way to go?

Buzz

 

[9kuuby9]

When your solution is spent then you could do the following;

Raise ph to 12 With NaOH, filter off or siphon the solution then neutralize the solution to a ph of 7 with HCl, discard the solution in the drainage. Save the (voluminous gelatinous sludge) hydroxides until you find a company where you can dispose it off.