# ammonia washing/reactions and precipitates



## au-artifax (Jun 5, 2013)

I have some questions regarding the use of ammonia during the refining process. Is it correct that if you introduce ammonia in your solution while there are still nitrates in your solution that you stand a good chance of creating fulminates, and subsequent disastrous effects?

Still though, my MAIN question is based on washing my precipitated gold. I isolated much of the gold before precipitation through various treatments before introducing nitric acid. I even precipitated gold out of my solutions where AP was used, and and also from some poormans solution, then threw the precipitated gold in with the main batch which was then dissolved in regular AR.
I removed the nitric with the evaporation method and know for certain all the nitric was gone. I got a great drop using a slight excess of SMB, .....
Now the washing, 3x boiling water (already the solution was comming out crystal clear) and no apparent visible loss of the mud, 2x boiling hcl (some slight color of Brown that cleared up and again crystal clear solution in the end) with no visible loss of mud,
BUT.... On washing the mud with concentrated ammonia water (full strength from no additive household ammonia) had a light Brown/amber colored solution that remained that color but was totally clear. There was a lot of popping sounds when I heated the mixture in a boiling flask. I saw no blue or white so I moved on to a rinse with distilled H2O.
When I added the DW however, I got an even darker brown/amber color in my wash that is cloudy and will not settle out after two days. There is still what appears to be the same amount of precipitate in the bottom of the flask.

Two questions: What is it that the ammonia did to my wash solution/precipitate? And will I be throwing any value away with this solution that does not test for gold? 

Any help would be appreciated. I cannot find the actual colors and appearance of the washes mentioned in any forum or Holkes (other than blue, purple, white, yellow, red, or black). At this stage of the refining I didn't expect any color at all. Is this normal? (Oops...that's a third question...isn't it?...and that's a fourth...etc...etc.


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## butcher (Jun 5, 2013)

Ammonia and metals salts (or precipitate from metals solutions) can form dangerous substances which could become explosive with pressure, shock or even temperature change, when dried.

Acidifying the solutions or powders can destroy the ammonium compounds and make them safe, after washing your gold with ammonia (to remove silver chloride) a wash with HCl will help to clean the gold and destroy the effects of the ammonia, acidifying the solution decanted from the gold will precipitate the silver and help to make the solution safer, but any time ammonia is used the waste solution should be kept separate from your other waste solutions.

I cannot say what brown the color of the ammonium solution came from, but several of the more reactive metals will dissolve in a base solution, if the base is strong enough even some of the less reactive metals can also be put into solution,some metals will precipitate from a mild base solution like ammonia, but will redissolve in an excess base solution like ammonia or sodium hydroxide, the Amphoteric metal oxides can include metals like silver, gold, tin, vanadium, iron, beryllium, aluminum, cobalt, germanium, zirconium, chromium, gallium, copper, lead, antimony, indium, zinc, silicon, titanium, as well as others.

I am not sure but you may be able to neutralize the brown solution and possibly get a precipitant, (or even acidify the precipitant if needed and test the solution for values), you could test it to determine which metal or metals it was that may have given you the brown color, I normally do not go to the trouble to find out, because the test used to qualitatively analyze these metals can become a long drawn out chemistry process of pretty much elimination of possibility's even before you come close to finding which metal you have, I find myself just trying to determine if it one of the valuable metals we seek.


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## au-artifax (Jun 5, 2013)

Thank you. My worst fear is that I totally destroyed the bonds/cementing from precipitation (smb), and now the simple addition of even distilled water puts the gold into suspension. In fact, I siphoned off the cloudy/muddy looking water leaving just the precipitate, added more distilled water, and got the same thing over again.... Cloudy muddy colored water. I will try to re-acidity the precipitate and siphoned off solutions to see if I can get whatever is in there to recement or drop. Keep the ideas comming and I will try adding some hcl to see what happens.


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## au-artifax (Jun 5, 2013)

Ok butcher..... I think I have this one part ways figured out. I didn't completely acidity the solution and the participate on the bottom, but put it just slightly below 7 on the acidic side to kill hthe ammonia. Then I heated slow to a boil and let it continue for five minutes. The cloudiness went away and lo-and-behold what d'ya think I'm smelling at this point?!?!
SULFUR!!!!!!!

Correct Mr if I'm wrong, but should I be thinking "incineration/calcinating at this point, before I keep washing this batch till the next millenium? Anyone reading this, feel free to comment.


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## butcher (Jun 6, 2013)

If it is excess SMB, you could try a little more hot HCl acid and Hot water washes, if I seen elemental yellow sulfur powder then I would incinerate off the sulfur.


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