Final ammonia water wash necessary ?

[Noxx]

Hello guys,
I would like to know if it's useful to final wash your gold powder with ammonia water after the HCl washes and water rinses ?

Of course I would rinse the powder two times with water after ammonia water.

I've eared that ammonia will dissolve other oxides and neutralize remaining HCl.

 

[Lou]

Yes it does all of that, but it is nice for removing copper.


Lou

 

[Noxx]

Alright, thanks for the input. I will implement this wash in my process.

 

[Harold_V]

Yep---what Lou said. It also removes traces of silver chloride that have a tendency to hitch a ride through the process. Adding the ammonia wash to my cycle was when my gold quality took a noticeable turn for the better.

Harold

 

[banjags]

what is the chemical called that you use... just household ammonia cleaner... aka windex or some other brand?

 

[Noxx]

Yes household will work. But be sure it's plain ammonia water, unscented.

Don't use windex. Look for ammonia only.

 

[Harold_V]

what is the chemical called that you use... just household ammonia cleaner... aka windex or some other brand?

I purchased mine from my chemical supply house----ammonium hydroxide, packaged in gallon plastic containers, six to the box.

What Noxx said, however. You need not buy from a supply house---just buy plain unscented ammonia from your local grocery store.

Harold

 

[donald236]

so if I'm understanding correctly you guys are saying that ammonia washes will take any of the contaminates that might be lurking around that you may have missed during all the processes :?: (ie h-cl)

 

[Harold_V]

Being basic, it will dissolve substances that may remain as a solid in acid. It is known to dissolve silver chloride, traces of which are commonly present in precipitated gold, assuming the gold contained any from the start. Jewelry almost always does (white gold contains no silver).

Rose (Sir T. K., not Meghan) documented the fact that a tiny portion of silver will behave like gold when they are mixed, so they are difficult to separate. By washing with ammonium hydroxide after precipitating gold, the traces that may have hitched a ride are removed, along with traces of copper that may not wash out with HCl.

An ammonia wash does wonders towards improving gold quality.

Harold

 

[donald236]

hey this is great to know thanks guys . i want my gold to be as pure as possible .

 

[draftinu]

Yes That is some helpful info. Thanks Guys!!!!!!!!!

 

[SilverNitrate]

I suggested that ammonium hydroxide be used to neutralize the acid, dissolve away traces silver chlorides and copper & the stronger the solution the better, but if its not available and if the fumes are too much to handle, a stiff sodium hydroxide solution will work just as well.

The OH- ligand in the NaOH will work similarly to the NH4+(NH3) of NH4OH(ammonia water) just that the NaOH has to be at very high concentration in water.

 

[skyline27]

Should the ammonia rinse be cold or hot?

 

[SilverNitrate]

Should the ammonia rinse be cold or hot?

warmer the better, it'l aide in the solubiltiy of the insoluable non-metallic components. also help drive away the ammonia smell when you drying.

 

[draftinu]

And as Noxx stated in the original post it needs a double rinse? Where I live our tap water is very high in chlorine content. Is it ok for me use water heated with a direct feed water supply from a Bunn coffee maker. This has a reservoir with hot water for dispensing for hot coco. I use this for my rinses. Is this ok? I know the chlorine is gone. Thanks, Tim

 

[Lobby]

Sorry to dredge up an old thread, but while it perfectly answered many of the questions I had on ammonia washes, there's a few it didn't.

- when doing hot HCl washes, I regularly find significant amounts of gold in the HCL. Dropping this gold is necessary, I've found. Do any values follow the ammonia wash liquid?

- if so, would stannous chloride detect them?

- would cementing these values with, say, copper drop them?

- is adding this ammonia solution to my normal stock pot a good idea?

- what sort of problems can I expect with an ammonia laden stock pot?

Thanks, folks. Sorry to be a pest. I'm trying to get my yields up.

 

[Lou]

You should not be having gold carry over in the hydrochloric acid. You are not precipitating the gold from a concentrated enough solution, so what's happening is that you are not waiting long enough for the gold to drop.

Ammonia will not solvate gold. As said up thread, it forms diammine silver (I) (colorless) and tetrammine copper (II) (very, very potent blue).


Keep ammonia out of any solution containing copper and silver, as it'll make waste treatment a real pain in the butt.
Probably easier to just add HCl to it until slightly acidic and then evaporate.

 

[Lobby]

You should not be having gold carry over in the hydrochloric acid. You are not precipitating the gold from a concentrated enough solution, so what's happening is that you are not waiting long enough for the gold to drop.

You are correct. I haven't been letting the dropped gold solution sit / settle overnight on the past few batches I've run. And in both of those batches, I've found gold in the HCl from the 1st gold powder wash step. I'll let the solution settle, per your advice (which others have given me, too). :lol:

Keep ammonia out of any solution containing copper and silver, as it'll make waste treatment a real pain in the butt.
Probably easier to just add HCl to it until slightly acidic and then evaporate.

Therefore there's no need to save the ammonium hydroxide wash solutions in the stock pot as there can be no gold in them?

 

[Lou]

Yep, that's what I'm saying.

 

[glondor]

Is there a method to recover the silver from the ammonium hydroxide wash solutions? Should it go to the stock pot?